Veerendra

Frank ICSE Solutions for Class 9 Biology – Bacteria and Fungi Their Importance

PAGE NO:127

Solution 1:

1.  Bacteria are a large group of unicellular, prokaryotic microorganisms.
2.  The bacteria which do not get stained with crystal violet and iodine solution are called gram negative bacteria while those bacteria which get stained with crystal violet and iodine solution are called gram positive bacteria.

Solution 2:

1. Bacteria shows the presence of cell wall, hence they are included under plants.
2.  Spore formation helps bacteria to survive during adverse environmental conditions. Hence it is a survival technique.
3.  Bacteria as friends :
   Bacteria are useful to us in many ways like producing antibiotics, forming curd and cheese, tanning leather, producing various industrial products, nitrogen fixation, digesting cellulose etc.
   Bacteria as foes:
   They are harmful in many ways like causing diseases, bio-weapons , food spoilage etc.
4. Yeast is used in breweries since the fermentation activity of yeast produces different types of beverages like wine, beer, alcohol toddy etc. In bakeries, when yeast is added to the flour its fermentation results in the production of carbon dioxide which produces soft bread and other bakery products.

Solution 3:

Solution 4:

Solution 5:

PAGE NO:128

Solution 6:

Solution 7:
(a) Penicillium notatum
(b) Aspergillus fumigatus
(c) Candida albicans
(d) Aspergillus

Solution 8:
(a) chitin
(b) saprophytic
(c) obligate aerobes
(d) Agaricus campestris

Solution 9:

Solution 10:
Fungi are cooked like vegetables or used in pulao or prepared as soups. Some common edible fungi are Agaricus, Ramaria, Clavaria, Morchella.
Also yeast is used in preparing idli and dosa from a mixture of powdered rice and dal.

Solution 11:
Yes. Many types of antibiotics are obtained from fungi which are used in medical sciences. Today about 25 types of antibiotics are commercially produced from moulds.
For example: Penicillin is obtained from the fungus Penicillium notatum.
Griseofulvin is extracted from the fungus Penicillium griseofulvum.

Solution 12:

Solution 13:

1. (b) Leeuwenhoek
2. (a) bacteria
3. (b) Bacillus
4. (a) Tuberculosis
5. (d) Rhizobium
6. (b) Lactobacillus
7. (d) Agaricus
8.  (a) ethyl alcohol

BiologyChemistryPhysicsMaths

Frank ICSE Solutions for Class 9 Biology – Diversity of Life and Classification

PAGE NO:117

Solution 1:
Diversity refers to the variety of living organisms found within a given ecosystem, biome, or on an entire planet.

Solution 2:
The method of arranging organisms into series of groups on the basis of similarities and differences is called classification.
Classification is important in the following ways:

1.  It makes the study of a wide variety of organisms easy.
2.  It gives us an overall picture of all the life-forms.
3. It helps us to understand the interrelationships among different groups of organisms.
4. It forms a base for the development of other biological sciences.

Solution 3:

Solution 4:
Taxonomy is the study of the theory, practice and rules of classification of living and extinct organisms.

Solution 5:
The five kingdom system of classification was proposed by R. H. Whittaker in 1969. This classification is based on the following four facts:

• Complexity of cell structure
•  Methods of nutrition (autotrophic or heterotrophic)
• Complexity of body organization.
•  Phylogenetic relationships.

The five kingdoms in this system are:

1. Monera – It includes all the prokaryotes like bacteria and cyanobacteria. They are important decomposers.
2.  Protista – It includes the aquatic, eukaryotic, acellular organisms like protozoans.
3. Fungi – This kingdom includes moulds, mushrooms and yeasts.
4. Plantae – It includes all the coloured, multicellular, eukaryotes with cell walls.
5.  Animalia – These are multicellular eukaryotes lacking cell wall and showing heterotrophic nutrition.

Solution 6:
Important characters of five kingdom are:
 Characters of kingdom Monera are:

1. It contains acellular organisms, ranging in size between 0.15  to 2.0 .
2.  They are prokaryotes, lacking a well-defined nucleus .
3. They usually lack chlorophyll and hence are parasites or saprophytes.
4. Reproduction occurs by binary fission or budding in bacteria.
   Example – Actinomycetes, bacteria, cyanobacteria.

Characters of kingdom Protista are:

1.  They are aquatic, unicellular organisms.
2. They have eukaryotic cells with well-defined nucleus and organelles.
3. They show autotrophic or heterotrophic mode of nutrition.
4. Some protists are parasites and few are decomposers too.
   Example – Euglena, Ameoba, Paramoecium.

 Characters of kingdom Fungi:

1.  They may be unicellular or multicellular.
2. They have heterotrophic nutrition and mostly they are saprophytes.
3. Their body is made up of mycelium, a filament of which is called hypha.
4.  Their cell wall is made up of chitin.
   Example – Aspergillus, Agaricus, Penicillium.

 Characters of kingdom Plantae:

1. They are multicellular, eukaryotic organisms.
2.  The cell membrane is surrounded by a thick cell wall of cellulose.
3. Except a few aquatic life forms, plants are non-motile.
4.  They have different modes of nutrition: autotrophic, parasitic even
   insectivorous.
   Example – Mango, Cycas, Fern, Moss.

 Characters of kingdom Animalia:

1.  They are multicellular, eukaryotic organisms without cell wall.
2. They show heterotrophic mode of nutrition.
3. They can retract or expand with the help of muscles.
4.  They are consumers in-between producers and decomposers.
   Example – Fish, Frog, Earthworm, Man.

Solution 7:
The kingdom Plantae has been divided into following groups:
Thallophyta 

•  They are consists of red, green and brown algae.
•  Algae are of universal occurrence.
•  Their body ranges from unicellular to multicellular colonies, filaments or sheets of cells.
• Vascular tissues are absent.
•  Nutrition is generally autotrophic (through photosynthesis).
• Reproduction is vegetative or sexual.

 Bryophyta

•  It consists of liverworts and mosses.
• They are terrestrial, found in damp, shady places.
•  Their life cycle has a long gametophytic phase and a short sporophytic phase.
• Liverworts have prostrate thalloid gametophytic body, but mosses have erect body.
• True roots are absent, but rhizoids presents.
•  Vascular tissues are absent.
•  Nutrition is generally autotrophic (through photosynthesis).
•  Reproduction is vegetative or sexual.

 Pteridophyta 

• They include ferns, horse-tails and club mosses.
• They occur mainly in cool, shady and moist places.
• They are mostly terrestrial.
• They are perennial herbs with stem in the form of rhizome.
•  Fibrous roots present.
• Their life cycle has a gametophytic phase and a short sporophytic phase.
•  Vascular tissues are present.
•  Nutrition is generally autotrophic (through photosynthesis).
•  Reproduction is vegetative or sexual.

 Spermatophyta 

•  They are the most successful terrestrial plants having seeds.
•  They produce seeds (fertilized ovules).
• They are divided into two groups –

1.  Gymnosperms -They bear naked seeds and lack flowers.
   Examples: Pine, Cycas
2. Angiosperms – They produce seeds enclosed in ovary and flowers
   are present.
   Examples: Rose, Grass

Solution 8:

Solution 9:

Solution 10:
The various classes of Chordata are:

1. Pisces – Labeo (Rohu), Scoliodon (Dog fish)
2. Amphibia – Rana (Frog), Hyla (Tree frog )
3.  Reptilia – Kanchuga (Tortoise), Naja naja ( Cobra)
4.  Aves – Columba (Pigeon), Pavo (Peacock)
5. Mammalia – Elephas ( Elephant), Funambulas (Squirrel)

Solution 11:

Solution 12:
Characters of mammals are:

1. The females of this class are provided with mammary glands which produces milk to feed the young one.
2. Body usually covered with hair, spines, scales, nail, hoof or horn.
3.  External ear or pinna is well-developed.
4. They are warm-blooded.

PAGE NO:118

Solution 13:
(a) Starfish belongs to phylum Echinodermata.
Two characters of starfish are:

1. Spines found on the body which is covered by calcareous plates.
2.  Body is star shaped with five radiating areas called ambulacra with inter-ambulacra in between.

(b) Whale belongs to phylum Chordata.
Two characters of whale are:

1. They are warm blooded marine animals.
2. Heart is completely four-chambered.

(c) Jelly fish belongs to phylum Coelenterata.
Two characters of jelly fish are:

1.  Body diploblastic having outer epidermis and inner gastrodermis with gelatinous mesoglea.
2. Tentacles are present around the mouth.

(d) Cockroach belongs to phylum Arthropoda.
Two characters of cockroach are:

1.  They have jointed legs.
2. Their exoskeleton is made up of chitinous cuticle which is shed from time to time.

Solution 14:

Solution 15:
Bryophyta – Liverwort and Moss.
Pteridophyta – Fern and Horsetail.

Solution 16:
Antedon (Sea lily) and Asterias (Star fish ).

Solution 17:
Whale

Solution 18:
Cockroach, crab

Solution 19:
Frog

Solution 20:
Echidna

Solution 21:
Earthworm – Pheretima posthuma and
Roundworm – Ascaris

Solution 22:

Solution 23:
(a) Arthropoda
(b) Porifera
(c) Mollusca

Solution 24:
(a) Protozoa
(b) Mollusca
(c) Annelida

Solution 25:
(a) Asterias (Star fish ), Echinus (Sea-urchin)
(b) Scoliodon (Dog fish), Labeo (Rohu)
(c) Fasciola ( Liver fluke), Taenia solium (Tapeworm)
(d) Ascaris ( Roundworm), Wuchereria (Filarial worm )
(e) Pheretima (Earthworm), Hirudinaria ( Leech )
(f) Palemon (Prawn), Periplaneta (Cockroach)

Solution 26:
(a) Annelida
(b) Coelenterata
(c) Arthropoda
(d) Echinodermata

Solution 27:
(a) Flame cells
(b) Nemathelminthes
(c) Annelida
(d) Porifera
(e) Chordata

Solution 28:

1. (a) three pairs of legs are present.
2. (a) coelentrata
3. (c) octopus
4. (c) paramoecium
5. (c) hippocampus
6. (a) Scorpion
7. (b) for five kingdom classification
8.  (a) prokaryotic and multicellular eukaryotic cell
9.  (d) plant
10. (d) C. Linnaeus
11. (c) Carolus Linnaeus

BiologyChemistryPhysicsMaths

Frank ICSE Solutions for Class 9 Physics – Light

PAGE NO: 261
Solution 1:
Convex mirror has a wider field of view.

Solution 2:
Convex mirror always produces an erect image of the object.

Solution 3:
Convex mirror is used in vehicles to see the traffic on rear side.

Solution 4:
We will use convex mirror to see an enlarged image of our face.

Solution 5:
Image of object placed at a long distance in front of a convex mirror is formed at principal focus. Radius of curvature of convex mirror is 20 cm.
Focal length of convex mirror = radius of curvature/2.
Focal length of convex mirror = 20/2 = 10 cm.
So image will form at principal focus 10 cm away from pole.

Solution 6:
Concave mirror can produce real and diminished image of the object.

Solution 7:
The distance of the principal focus from the pole of the mirror is called the focal length of the mirror.

Solution 8:
The mirror having +20 cm as its focal length is a convex mirror because focal length is taken positive only in case of convex mirror.

Solution 9:
The focal length of plane mirror is infinity.

Solution 10:
The mirror having -15 cm as its focal length is a concave mirror because focal length is taken negative only in case of concave mirror.

Solution 11:
Principal axis is the straight line passing through the pole and the centre of curvature.

Solution 12:
Linear magnification is defined as the ratio of the height of the image to the height of the object. It is taken to be positive for an image to be virtual and erect and negative when image is real and inverted.
Magnification = height of image / height of object.

Solution 13:
Pole is the centre of the reflecting surface, in this case spherical mirror.

Solution 14:
Centre of curvature is the centre of the imaginary sphere to which the mirror belongs.

Solution 15:
Three characteristics of light are:-

• Light waves can travel through vacuum.
• Light waves are transverse waves.
• The velocity of light in vacuum is 3 x 10⁸ m/s.

Solution 16:
Three distinctions between light and sound waves are

• Light waves can travel through vacuum while sound waves cannot.
• Light waves are transverse waves while sound waves are longitudinal waves.
• The velocity of light in air is 3 x 10⁸ m/s while the speed of light in air is just about 330 m/s.

Solution 17:

• When position of object is at infinity, concave mirror forms a point and Real image at Focus point.
• When position of object is beyond C, concave mirror forms a Diminished, Real and inverted image between F and C.
• When position of object is at C, concave mirror forms a Magnified, Real and inverted image at C.

Solution 18:
Image formed by a convex mirror is always Diminished, Virtual and Erect.

Solution 19:
Concave mirrors are used in reflecting microscope, in shaving and make up glasses and in ophthalmoscope.

Solution 20:

• The distance from the pole in the direction of incident ray is taken positive.
• The distance from the pole in the direction opposite to the incident ray is taken negative.

Solution 21:
Mirror formula is the relation between the focal length f of the mirror, the distance u of the object from the pole of the mirror, and the distance v of the image from the pole.
Mirror formula is
1/v +1/u = 1/f.
Linear magnification is defined as the ratio of the height of the image to the height of the object. It is taken to be positive for an image to be virtual and erect and negative when image is real and inverted.
Magnification = height of image / height of object.

Solution 22:
Mirror formula is the relation between the focal length f of the mirror, the distance u of the object from the pole of the mirror, and the distance v of the image from the pole.
Mirror formula is
1/v +1/u = 1/f.
Size of body = 1.5 m.
Magnification of body = 1.5.
Magnification = height of image / height of object.
Height of image = magnification x height of object.
Height of image = 1.5 x 1.5= 2.25 m.

Solution 23:
Linear magnification is defined as the ratio of the height of the image to the height of the object. It is taken to be positive for an image to be virtual and erect and negative when image is real and inverted.
Magnification produced by concave mirror is:
Magnification = height of image / height of object.
It is a pure ratio and does not have any units.

Solution 24:

Solution 25:
A smooth and polished surface causes regular reflection while a rough and unpolished surface causes irregular reflection.

Solution 26:
When rays of light fall on a surface, they are turned back into the same medium in accordance with some definite laws. This process is known as reflection.
Reflection obeys following two laws

• The incident ray, the reflected ray, and the normal at the point of incidence, all lie in the same plane.
• The angle of incidence and the angle of reflection are always equal.

Solution 27:
You can distinguish between plane mirror, a concave mirror, and a convex mirror without touching them. When you look into these mirrors by bringing your face close to each mirror, they will produce an image of your face of different types.

• A plane mirror will produce an image of the same size as your face.
• A concave mirror will produce a magnified image of your face.
• A convex mirror will produce Diminished image of your face.

Solution 28:
You can distinguish between a concave mirror and a convex mirror without touching them. When you look into these mirrors by bringing your face close to each mirror, they will produce an image of your face of different types.

• A concave mirror will produce a magnified image of your face.
• A convex mirror will produce Diminished image of your face.

PAGE NO : 262
Solution 29:

Solution 30:
Uses of concave mirror:

• Concave mirrors are used in reflecting microscope
• Concave mirrors are used in shaving and make up glasses.
  Uses of convex mirror: Convex mirrors are used as a rear view mirror in automobiles as it provides a wider view of following traffic.

Solution 31:
We can see the reflection of our face on a polished table top because a regular reflection occurs in case of a polished surface while on a unpolished table top irregular reflection occurs which make image of our face unclear.

Solution 32:

• The angle of incidence is the angle made by the incident ray with the plane mirror. {FALSE}
  Correct statement is the angle of incidence is the angle made by the incident ray with the normal to the surface of plane mirror.
• If a ray of light incident on a plane mirror is such that it makes an angle of 30° with the normal, then the angle of reflection is 60°.{FALSE}
  Correct statement is if a ray of light incident on a plane mirror is such that it makes an angle of 30° with the normal, then the angle of reflection is 30°.
• If the incident ray makes an angle of X° with the normal, then the angle between the incident ray and reflected ray is 2X°. {TRUE}
• The image formed in a plane mirror is real, erect and same size as that of the object. {FALSE}
  Correct statement is the image formed in a plane mirror is virtual, erect and same size as that of the object.

Solution 33:

Solution 34:

Solution 35:
The image formed by a plane mirror is erect and virtual. It is a laterally inverted image. The image formed is of the same size as that of the object. Also, the image and the object are equidistant from the mirror.

Solution 36:

Solution 37:
Given, distance of boy from the mirror = 3 m

• Distance of image from mirror = distance of boy from the mirror = 3 m
  Distance between boy and his image = distance of boy from the mirror + distance of image from mirror = 3+3 = 6 m
• Now, distance of boy from the mirror = 4 m
  Distance of image from mirror = 4 m
  Distance between boy and his image = distance of boy from the mirror + distance of image from mirror = 4+4 = 8m.

Solution 38:
Periscope is used to see over the top of an obstacle. It is also used in submarines for observing for movement of ships. It can be used from the trenches for observing the movement on the surface of earth.

PAGE NO : 263
Solution 39:

Solution 40:

• Pole is the centre of the reflecting surface, in this case spherical mirror.
• Centre of curvature is the centre of the imaginary sphere to which the mirror belongs
• Principal focus of a spherical mirror is a point on the principal axis of the mirror, where all the rays travelling parallel to the principal axis and close to it after reflection from the mirror, converge to or appear to diverge from.
• Principal axis is the straight line passing through the pole and the centre of curvature.
• Focus of a concave mirror is a point on the principal axis of the mirror, where all the rays travelling parallel to the principal axis and close to it after reflection from the mirror converge to that point.
• Normal to the surface of a mirror at any point is the straight line at right angle to the tangent drawn at that point.

Solution 41:

Solution 42:

Solution 43:

Solution 44:

Solution 45:

Solution 46:

PAGE NO : 264
Solution 47:

Solution 48:

Solution 49:

Solution 50:

PhysicsChemistryBiologyMaths

Frank ICSE Solutions for Class 9 Physics – Light: Spherical Mirrors

PAGE NO: 258
Solution 1:
A spherical mirror is a part of a hollow glass sphere silvered on one side.

Solution 2:

Solution 3:
Focal length = 1/2 of radius of curvature
= 1/2 x 30 = 15cm.

Solution 4:
Focal point is the principal focus of the mirror where a parallel beam of light meets(or appear to meet) after reflection from the mirror.

Solution 5:

Solution 6:

• Pole is the centre of the reflecting surface, in this case spherical mirror.
• Centre of curvature is the centre of the imaginary sphere to which the mirror belongs
• Aperture is the distance between the extreme points on the periphery of the mirror.
• Principal axis is the straight line passing through the pole and the centre of curvature.
• The principle focus of a spherical mirror may be defined as a point on its principle axis where a beam of light parallel to the principle axis converges to or appears to diverge from after reflection from the spherical mirror.

Solution 7:
Convex mirror has a wider field of view.

Solution 8:
Concave mirrors are used in reflecting microscope, in shaving and make up glasses and in ophthalmoscope.

Solution 9:
Convex mirrors are used as a rear view mirror in automobiles as it provides a wider view of following traffic.

Solution 10:
Convex mirror is used in vehicles to see the traffic following it.

Solution 11:
The relationship between the focal length, f and radius of curvature, r is
f = 1/2 x r.

Solution 12:

Solution 13:

Solution 14:
Concave mirror can produce real and diminished image of the object.

Solution 15:
The focal length of plane mirror is infinity.

Solution 16:
The object should be placed between F and P to obtain its magnified and erect image.

Solution 17:

Solution 18:
Linear magnification is defined as the ratio of the height of the image to the height of the object. It is taken to be positive for an image to be virtual and erect and negative when image is real and inverted.
Magnification = height of image / height of object.

Solution 19:
SI unit of focal length is meter.

Solution 20:
The top mirror is convex mirror, the middle mirror is concave mirror and bottom mirror is a plane mirror.

Solution 21:
The mirror having +15 cm as its focal length is a convex mirror because focal length is taken positive only in case of convex mirror.

Solution 22:
The mirror having -20 cm as its focal length is a concave mirror because focal length is taken negative only in case of concave mirror.

Solution 23:
When we look into a plane mirror, the image of our face is virtual because the image cannot be obtained on a screen.

Solution 24:
When an object is brought towards the concave mirror, the position of the image moves away from the mirror and the size increases and it remains inverted but at object position between F and P, the image is virtual, magnified and erect.

Solution 25:

PAGE NO : 259
Solution 26:

Solution 27:

Solution 28:

Solution 29:

Solution 30:

PhysicsChemistryBiologyMaths

Frank ICSE Solutions for Class 9 Physics – Light: Reflection of Light

PAGE NO: 245
Solution 1:
Light may be defined as the radiant energy which produces in us the sensation of sight. Light itself is invisible but makes other objects visible.

Solution 2:
Yes, light is a form of energy that produces the sensation of vision in our eyes.

Solution 3:
The velocity of light in vacuum is 3 x 10⁸ m/s.

Solution 4:
Two sources of light are

• Natural, for e.g. Sun
• Artificial, for e.g. Light bulb.

Solution 5:
Four characteristics of light are :-

• Light waves can travel through vacuum
• Light waves are transverse waves
• Wavelength of light waves is short so that their length is measured in centi-microns.
• The velocity of light in vacuum is 3 x 10⁸ m/s.

Solution 6:
The Sun and the stars are the two luminous bodies.

Solution 7:
Two non -luminous bodies are moon, chair.

Solution 8:

Solution 9:
A ray of light is the path along which light travels.

Solution 10:
Three distinctions between light and sound waves are

• Light waves can travel through vacuum while sound waves cannot.
• Light waves are transverse waves while sound waves are longitudinal waves.
• The velocity of light in air is 3 x 10⁸ m/s while the speed of light in air is just about 330 m/s.

PAGE NO : 246
Solution 11:

• A ray of light
• Divergent beam of light
• Divergent beam of light
• Parallel beam of light

Solution 12:
The substance through which light is made to pass is called medium.

Solution 13:
Rectilinear propagation of light is that the light travels along a straight line.

Solution 14:
No, glass is a transparent medium.

Solution 15:
No, no metal is transparent by nature.

Solution 16:

Solution 17:
Waxed paper is the translucent medium among the given substances.

Solution 18:

Solution 19:
Two observations that proves that light travels in a straight line are :-

• Sunlight coming through a hole in a dark room, we can easily see that light travels in a straight line
• Light coming from a laser light, used for presentation, can also be seen to travel in straight line.

Solution 20:
When rays of light fall on a surface, they are turned back into the same medium in accordance with some definite laws. This process is known as reflection.

Solution 21:
A smooth and polished flat surface is the cause of regular surface.

Solution 22:
Reflection obeys following two laws

• The incident ray, the reflected ray, and the normal at the point of incidence, all lie in the same plane.
• The angle of incidence and the angle of reflection are always equal.

Solution 23:
The height of plane mirror should be half of the size of the object to get a full image of the object. So for a man of height 1.6 m tall should use a 0.8m tall plane mirror.

Solution 24:
Rectilinear propagation of light is that the light travels along a straight line.

Solution 25:
Lateral inversion is the reversal of image experienced in a plane mirror. The image is of the same size and equidistant from the object but the left and right sides are transposed.

Solution 26:
Formation of image is the phenomenon based on laws of reflection.

Solution 27:
The principle employed in a periscope is successive reflections from two plane mirrors.

Solution 28:
The point at which the light is incident on the reflecting surface is called the point of incidence.

Solution 29:
Any smooth, highly polished reflecting surface is called mirror.

Solution 30:
A smooth, highly polished plane surface is called plane mirror.

Solution 31:
The angle between the incident ray and the normal to the surface at the point of incidence is called the angle of incidence.

Solution 32:

Solution 33:
Given, angle between incident ray and mirror = 35°

• Angle of incidence = angle of mirror to the normal – angle between incident ray and mirror
  = 90 – 35 = 55°
• Angle of reflection = angle of incidence = 55°
• Total angle turned = angle of incidence + angle of reflection
  = 55 + 55 = 110°
• The angle between incident ray and reflected ray = Angle of incidence + Angle of reflection
  = 55 + 55 = 110°

Solution 34:
Given, distance of boy from the mirror = 3 m

• Distance of image from mirror = distance of boy from the mirror = 3 m
  Distance between boy and his image = distance of boy from the mirror + distance of image from mirror = 3+3 = 6 m
• Now, distance of boy from the mirror = 4 m
  Distance of image from mirror = 4 m
  Distance between boy and his image = distance of boy from the mirror + distance of image from mirror = 4+4 = 8 m.

Solution 35:

PAGE NO : 247
Solution 36:
Two characteristics of image formed by plane mirror are

• Image is erect and virtual
• Image and object are of same size.

Solution 37:

Solution 38:

Solution 39:

PhysicsChemistryBiologyMaths

Frank ICSE Solutions for Class 9 Physics – Heat: Transmission of Heat

PAGE NO: 226
Solution 1:
Conduction, convection and radiation are three modes of transfer of heat.

Solution 2:
The process of conduction involves the transmission of heat from the hot end to the cold end from particle to particle of the medium.

Solution 3:
No, conduction is not possible in vacuum.

Solution 4:
Thermal insulation means restriction of transfer of heat by any means.

Solution 5:
Good conductor allow heat to pass through them easily while bad conductor of heat does not allow heat to pass them.

Solution 6:
No, liquids are poor conductors of heat.

Solution 7:

• Metals are the best conductor of heat.
• Gases are the worst conductor of heat.

Solution 8:
Among all the metals, Silver is most conducting.

Solution 9:
Air is most non-conducting.

Solution 10:
No, air is not a good conductor of heat.

Solution 11:
Yes, this is a correct statement. Ebonite and asbestos are worst conductor of heat.

Solution 12:
Cooking utensils are made up of metals because metals are good conductors of heat and they easily allow the heat to pass through them.

Solution 13:
Brick is bad conductor of heat, hence bricks greatly reduce the conduction of heat from outside to the room. In order to ensure better insulation, bricks are made hollow so that air filled between these gaps provides insulation to heat.

Solution 14:
Mercury is good conductor of heat.

Solution 15:
In cold countries, windows have two glass panes and a thin layer of air in between these two glass panes because air is a poor conductor of heat; it obstructs the conduction of heat from the room to the outside.

Solution 16:
Order of increasing heat conductivity:
Air < water< mercury < copper.

Solution 17:

• Water is heated from below because water is heated by process of convection and in process of convection heat always flows in upward direction from downward direction.
• In process of convection heat is transferred from one point to another by actual movement of particles of medium and as particles of solid cannot move so process of convection is not possible in case of solids.
• Conduction is not possible in Vacuum because process of conduction require a material medium for transfer of heat.
• Inside the refrigerator, cooling takes place by convection. The freezing chamber at the top produces cool and heavy air which descends and hot air from below goes up setting convection current. Thus, cooling in a refrigerator is kept near the top.
• As earth surface gets heated by sun rays and due to process of convection the air near earth surface open to sunlight get heated while in shade sun rays does not fall on earth surface so air near that surface would not heat up.

Solution 18:

Solution 19:

PAGE NO : 227
Solution 20:
We receive heat from sun by process of Radiation.

Solution 21:
Radiating power of a surface can be increased by blackening it.

Solution 22:
Heat radiation travels with speed of light and always follows straight path.

Solution 23:
The flask consists of a double walled glass container with vacuum between the walls A and B. The inner side of A and the outer side of B are silvered. It has a narrow mouth which is closed by a non-conducting rubber stopper.
If a hot liquid is placed inside the flask, it cannot lose heat by conduction or convection, as there is no air between the walls. The small amount of heat lost from the liquid by radiation is reflected back into the liquid by silvering of the inner wall A and any radiation striking the outer wall B, is reflected back and prevented from reaching the liquid.

Solution 24:
Green house is a glass house constructed to keep delicate and rare plants that require warmth and protection from weather. It is constructed by panels of glass. The temperature in a green house rises because heat enters the house through the glass but cannot escape out, because the glass reflects the heat back to the inside of the house. This makes glass house warmer than the outside environment.

Solution 25:
Take two sheets of tin plates, one blackened and the other is polished brightly. Fix some drawing pins on the outer side of both sheets using wax. Fix these plates vertically at a very short distance apart. Place a Bunsen burner midway between them. When you light the burner you will observe that the pins from the black painted sheet start dropping while the pins on the polished surface remain in the same position for much longer time.
Thus, we can conclude that black surface is better absorber of heat than the polished one.

Solution 26:

• As convection require medium for transfer of heat so heat loss due to convection can be minimized if the substance is kept away from any material medium.
• Similarly for conduction, as conduction also require medium for transfer of heat so heat loss due to conduction can be minimized if the substance is kept away from any material medium.
• Heat loss due to radiation can be minimized by polishing the surface as polished surfaces radiate less heat.

Solution 27:

• As no material medium surrounds the ball so there is no possibility of losing heat by conduction or convection. The ball will lose heat by Radiation.
• Ball will lose minimum amount of heat if it is polished.
• As loss of heat take place by Radiation and process of radiation does not require any material medium, so there is no role of air in loss of heat.

Solution 28:

• CFC means Chlorofluorocarbons which are produced mainly by refrigeration industries, aerosol cans, coolants, propellants and plastic foams. They cause global warming.
• UV means ultraviolet range of radiations. These are the radiations which are emitted by sun and they enter our atmosphere.
• WHO is World Health Organization which put a check on diseases and global warming etc.

Solution 29:
Green house is a glass house constructed to keep delicate and rare plants that require warmth and protection from weather. It is constructed by panels of glass. The temperature in a green house rises because heat enters the house through the glass but cannot escape out, because the glass reflects the heat back to the inside of the house. This makes glass house warmer than the outside environment. This phenomenon is called green house effect.

Solution 30:
Carbon dioxide, Carbon monoxide, methane are green house gases.

Solution 31:
As fossil fuels are non-renewable sources of energy they are not available again and again if are fully exhausted, so they should not be used extensively.

Solution 32:
Global warming occurs due to the presence of carbon di- oxide, CFCs, methane in the atmosphere. Carbon dioxide acts as a transparent gas to incoming shortwave radiations which the earth re-radiates into space. It therefore traps the outgoing longwave radiations thus warming lower atmosphere of the earth thereby causing global warming.

Solution 33:
Harmful effects of global warming are:

• The atmospheric temperature of earth would increase thereby making it difficult for a living being to survive.
• It would melt down the polar caps thus increasing the size of the ocean and leading to floods, tsunami, etc.
• The increase in temperature would affect climate and rainfall thus affecting flora and fauna.
• Human beings would be vulnerable to diseases as microbes would get warmth to grow.

PhysicsChemistryBiologyMaths

Frank ICSE Solutions for Class 9 Physics – Heat: Thermometry

PAGE NO: 209
Solution 1:
Temperature is the quantity that tells about the thermal state of a body i.e. the degree of hotness or coldness of a body.

Solution 2:
Thermometer is used for measuring the temperature of a body.

Solution 3:
Thermometer works on the principal that substances expand when heated and contract on cooling.

Solution 4:
Range of thermometer is the range of temperature which can be measured by thermometer.

Solution 5:
Mercury is the liquid used in a clinical thermometer

Solution 6:
The usual range of temperature marked on clinical thermometer is 95° F to 110°F.

Solution 7:
Fahrenheit designed the first thermometer.

Solution 8:
Before constructing a thermometer, we determine lower fixed point and upper fixed point and divide the whole range of thermometer into specific number of equal divisions to provide a scale for measuring the temperatures within a range.

Solution 9:
The clinical thermometer is specially designed thermometer used to measure the temperature of a human body easily and as accurately as possible.

Solution 10:
Three properties of a liquid which make it suitable to be used in a thermometer are:

• The substance should have high coefficient of expansion so that it is sensitive to the smallest change in temperature
• The substance should have uniform expansion all over its entire volume
• The substance should have minimum specific heat so that it absorbs minimum heat from the body under measurement.

Solution 11:
Two disadvantages of using mercury as a thermometric liquid:

• It does not have uniform expansion.
• Mercury is less sensitive than alcohol as its coefficient of expansion is less than alcohol.

Solution 12:
Three advantages of using mercury as a thermometric liquid:

• Mercury is good conductors of heat.
• Mercury have high coefficient of expansion thus is sensitive to the smallest change in temperature.
• Freezing points is very low and boiling point is high.

Solution 13:
Water is not used as a thermometric liquid because it has low coefficient of expansion so it is less sensitive to temperature changes. Moreover, it is transparent thus making it difficult to read the thermometer and water evaporates with time thus producing error and also the freezing and boiling points are also low.

Solution 14:
Temperature in Kelvin To K = Temperature in Celsius To C + 273.
To K = 0°C + 273
To K =273 K.

Solution 15:
Body temperature of a healthy person is 98.4oF.
We know C/100 = (F – 32)/180.
C =5/9(F- 32)
C = 5/9(98.4 – 32)
C = 5/9 x 66.4
C =36.88°C
Temperature of body of healthy man is 36.88°C.

Solution 16:
Absolute scale of temperature is Kelvin scale.
Conversion of temperature from Celsius to Kelvin scale is
Temperature in Kelvin To K = Temperature in Celsius To C + 273.
So a rise of temperature of 1°C in Celsius scale is equal to rise of 1°K in Kelvin scale.

Solution 17:
Kelvin temperature scale is used in SI system.

Solution 18:
In Celsius scale there are two fixed points namely lower fixed point and upper fixed point at 0°C and 100°C respectively. This range is divided into 100 equal divisions and each part gives 1°C.

Solution 19:
We know C/100 = (F – 32)/180.
C =5/9(F- 32)
9/5 C + 32 =F
F = 9/5 C + 32.
Temperature given in Celsius = -15°C.
F = 9/5 x (-15) +32
F = -27 +32
F = 5°F.

Solution 20:
Absolute zero of temperature is 0°K.
Temperature in Kelvin To K = Temperature in Celsius To C + 273.
0°K = To C +273.
To C = -273°C.
Absolute zero of temperature on Celsius scale is -273°C.

Solution 21:
Difference of temperature of two bodies in Celsius scale = 1°C.
We know C/100 = (F – 32)/180.
C =5/9(F- 32)
9/5 C + 32 =F
F = 9/5 C + 32.
So, difference of 1° in Celsius scale is equal to the difference of 9/5° in Fahrenheit scale.
Thus, Difference of 1°C of temperature of two bodies in Celsius scale is equal to difference of 1.8° in Fahrenheit scale.

Solution 22:
Celsius invented the Celsius scale of temperature.

Solution 23:
Fahrenheit invented the Fahrenheit scale of temperature.

Solution 24:
Mercury, alcohol are commonly used in thermometers.

PAGE NO : 210
Solution 25:
Camel and are two animals which are able to increase their body temperature in summers and decrease their body temperature in winters.

Solution 26:
CGS unit of heat is Joule denoted by J.
1 J is amount of heat required to raise the temperature of a body by 1/4.12°C of temperature.

Solution 27:

Solution 28:

Solution 29:
Relation between Celsius and Fahrenheit scales of temperature is
C/100 = (F – 32)/180.

Solution 30:
Temperature of ice point on Fahrenheit scale =32°F.
Temperature of steam point on Fahrenheit scale =212°

PhysicsChemistryBiologyMaths

Frank ICSE Solutions for Class 9 Physics – Heat: Thermal Expansion

PAGE NO: 202
Solution 1:

• Coefficient of Linear expansion is equal to the change in length of a rod of length 1m when its temperature rises by 1°c.
• Coefficient of superficial expansion is equal to the change in area of a rod of area 1m² when its temperature rises by 1°c.
• Coefficient of volume expansion is equal to the change in volume of a rod of volume 1m³ when its temperature rises by 1°c.

Solution 2:

Solution 3:
A bimetallic strip consists of two metal strips- one with high coefficient of expansion and the other with low coefficient of expansion. Two different metals are used for regulating temperature in an electrical device as the strip bends due to different coefficient of expansion on excessive heating due to current, thus breaking electrical circuit until the strip cools down to a preset point. Two applications of bimetallic strip are thermostat in electric iron and in balance wheels.

• When boiling water is poured into a glass bottle, it generally cracks because on pouring hot water in the bottle the inner surface heats up and expands more as compared to its outer surface. This unequal expansion between the two surfaces causes a strain and the bottle cracks.
• Telephone wires sag in summer because due to heat of the sun, the wire expands and increases in length, thus they sag in summer.
• In cold countries water pipes burst in winter because the water has maximum density at 4°C and, due to anomalous expansion of water, it expands when the water is cooled to a temperature below 4°C
• Even when the water in the lakes is frozen, fishes can survive due to anomalous expansion of water, water has maximum density at 4°C and this dense water remains at the bottom of the lake and the upper layer of water is less dense and freezes but the temperature of each layer of water below increases by 1°C. Thus it is warmer in the lakes below the ice layer. This helps the fishes to survive.

Solution 4:

Solution 5:
Thermostat is a device for regulating temperature in electric circuits and it is made up of bimetallic strip. Two applications of thermostat are in electric iron and in refrigerators.

Solution 6:
When heated, water expands normally but behavior of water is unusual over a small range of temperature between 0 and 4°C. This is known as anomalous expansion of water.

Solution 7:
Anomalous expansion of water slows down the complete freezing of water in the lake.

Solution 8:

Solution 9:

• When boiling water is poured into a glass bottle, it generally cracks because on pouring hot water in the bottle the inner surface heats up and expands more as compared to its outer surface. This unequal expansion between the two surfaces causes a strain and the bottle cracks.
• Telephone wires sag in summer because due to heat of the sun, the wire expands and increases in length, thus they sag in summer.
• In cold countries water pipes burst in winter because the water has maximum density at 4°C and, due to anomalous expansion of water, it expands when the water is cooled to a temperature below 4°C
• Even when the water in the lakes is frozen, fishes can survive due to anomalous expansion of water, water has maximum density at 4
• When boiling water is poured into a glass bottle, it generally cracks because on pouring hot water in the bottle the inner surface heats up and expands more as compared to its outer surface. This unequal expansion between the two surfaces causes a strain and the bottle cracks.
• Telephone wires sag in summer because due to heat of the sun, the wire expands and increases in length, thus they sag in summer.
• In cold countries water pipes burst in winter because the water has maximum density at 4°C and, due to anomalous expansion of water, it expands when the water is cooled to a temperature below 4°C.
• Even when the water in the lakes is frozen, fishes can survive due to anomalous expansion of water, water has maximum density at 4°C and this dense water remains at the bottom of the lake and the upper layer of water is less dense and freezes but the temperature of each layer of water below increases by 1°C. Thus it is warmer in the lakes below the ice layer. This helps the fishes to survive °C and this dense water remains at the bottom of the lake and the upper layer of water is less dense and freezes but the temperature of each layer of water below increases by 1°C. Thus it is warmer in the lakes below the ice layer. This helps the fishes to survive.

Solution 10:

Solution 11:

PAGE NO : 203
Solution 12:

• Maximum
• Increases; decreases
• Coefficient; expansion
• Anomalous expansion of water
• Calorie
• Kelvin(K)

Solution 13:
We should heat the neck of the bottle because due to heating the neck will expand and loosen the stopper stuck in the neck. In this way, we can easily remove the stopper.

Solution 14:
When a liquid is heated in a flask. Due to heat, the flask expands along with the liquid, thus providing more space for the liquid. Hence the level of the liquid falls. Thus this dropped level shows the apparent expansion of the liquid. The actual expansion of the liquid, when heated, is the real expansion.

Solution 15:
No, the both liquids i.e. mercury and alcohol will not have same volume on heating as they have different coefficient of expansions, thus they expand differently on heating at same temperature range. Alcohol expands more than mercury.

Solution 16:

Solution 17:

Solution 18:
A hot glass chimney often crack when a drop of water falls on it because the glass of the chimney expands due to constant heating by the flame of the chimney but as a cooler water drop falls on the glass, the outer surface contracts more than the inner side of the glass. . This unequal contraction between the two surfaces causes a strain and the glass cracks.

Solution 19:
No, we cannot fuse iron wire in glass rod because glass is bad conductor of heat and it does not allow heat to pass through it and iron wire would not be able to get sufficient heat to fuse.

Solution 20:
We should heat the neck of the bottle because due to heating the neck will expand and loosen the stopper stuck in the neck. In this way, we can easily remove the stopper from the bottle.

Solution 21:
Two substances that expand on heating are water and iron.

Solution 22:
Two substances that contract on heating are plastic and poly-ethene.

Solution 23:

Solution 24:
The joints in metal pipes loosen in summers because the joints get more space to expand due to the heat in summers as compared to the pipes therefore the joints become loose in summers

Solution 25:
The increase in length of a rod depends on the following factors

• material of the rod
• Original length of the rod
• Rise in temperature

Solution 26:
The given statement states that the change in length of the metal will be 0.000016 m when its temperature changes by 1°C.

Solution 27:
On heating the copper washer

• Its internal diameter will increase as the copper washer expands outwards
• Volume will increase as the size of the metal expands on heating
• Mass will remain the same as the mass does not change with change in temperature
• Density will decrease as the volume of the washer increases on heating and density is inversely proportional to volume
• External diameter will increase because the copper washer expands outwards

Solution 28:

Solution 29:
At 4°C, water has the maximum density due to anomalous expansion.

Solution 30:

PhysicsChemistryBiologyMaths

Frank ICSE Solutions for Class 9 Physics – Heat

PAGE NO: 191
Solution 1:
Heat is defined as a form of energy which flows from one point to another on account of temperature difference.

Solution 2:
Yes, heat is a form of energy

Solution 3:
Joule is the SI unit of heat.

Solution 4:
One calorie is defined as the quantity of heat required to raise the temperature of 1 gram of water through 1°C.

Solution 5:
1 calorie = 4.2 joules.

Solution 6:
Temperature is the degree of hotness or coldness of a body compared to other bodies around it.
SI unit of temperature is Kelvin (K).

Solution 7:
We feel cold on touching ice because heat flows from our warm hands to cold ice. Due to this flow of heat from hand to ice, the temperature of our hand falls. This is why we feel cold.

Solution 8:

Solution 9:
Heat flows from a body at a higher temperature to a body of lower temperature.

Solution 10:
Yes, heat is the cause of temperature because temperature of a body rises when the heat flows into the body.

Solution 11:
Heat changes the temperature of a body due to flow of heat in or out of the given body.

Solution 12:
Calorie. Because 1 calorie = 4.2 joules.

Solution 13:
No, the exact relation is as given
1 calorie = 4.2 joules.

Solution 14:
Yes, because the heat flow is only due to temperature difference between the temperature of two bodies.

PAGE NO: 229
Solution 1:
Temperature is the degree of hotness or coldness of a body compared to other bodies around it.
SI unit of temperature is Kelvin (K)

Solution 2:
Normal temperature of human body is 37°C.

Solution 3:
To convert 20°c into °F
T°C /100 = (T°f -32)/180
20/100 = (T°f – 32)/180
20 x 180/100 = T°f -32
T°f = 36+32 = 68°F

Solution 4:
Upper fixed point on the Celsius scale is 100°C.

Solution 5:
T_k = 80 K
T_c = T_k -273
T_c = 80 – 273
T_c = -153°C

Solution 6:
SI unit of latent heat is Joule per kg (J/kg).

Solution 7:
Relative humidity is defined as the amount of water vapour in the air compared to the amount needed for saturation.

Solution 8:
Coefficient of Linear expansion is equal to the change in length of a rod of length 1m when its temperature rises by 1°C. Its SI unit is °C^-1.

Solution 9:
Celsius was the scientist who discovered the first thermometer in 1710.

Solution 10:
According to principle of calorimetry of mixtures,
Heat gained = Heat lost

Solution 11:
SI unit of coefficient of cubical expansion is °C^-1.

Solution 12:
Two uses of bimetallic strip are

• As thermostat in electric iron
• As balance wheel in watches

Solution 13:
Telephone wires sag in summer because due to heat of the sun, the wire expands and increases in length, thus they sag in summer.

Solution 14:

Solution 15:
Not all substances expand on heating. Some examples of substances which do not expand on heating are plastics, polythene and rubber.

Solution 16:
Evaporation is the phenomenon of a change of a liquid into vapour without raising the temperature. Evaporation needs energy for phase change from liquid to gases. As water evaporates off your skin, it absorbs energy(heat) from the body to make the phase change to gas thus cooling the body.

Solution 17:
Factors affecting evaporation are

• Humidity- more the humidity less is the evaporation
• surface area- more the surface area more is the evaporation
• wind- more the wind more is the evaporation
• temperature- more the temperature more is the evaporation

Solution 18:
The cold air that blows from land towards sea during night, is called land breeze
The cold air that blows from the sea towards the land during the day is known as the sea breeze. These breezes are the examples of natural convection current.

Solution 19:
No, the conduction is not possible in gases. Gases are bad conductors.

Solution 20:
No, conduction is not possible in vacuum.

Solution 21:
The velocity of thermal radiations is equal to the speed of light i.e. 3 x 10⁸ m/s.

PAGE NO : 230
Solution 22:
We wear woolen clothes in winter because woolen clothes have tiny pores and air is trapped in these pores and being a bad conductor, the trapped air obstructs the flow of body heat to the surroundings.

Solution 23:
A newly made quilt is warmer than an old one because the cotton in the old quilt gets compressed and very little air will remain trapped in it, hence heat insulation is quite poor.

Solution 24:
In cold countries, water pipes are covered with poor conductors because poor conductor prevents water from freezing and thus prevent these pipes from bursting.

Solution 25:
Three devices used to detect heat radiations are

• Blackened bulb thermometer
• Differential air thermo scope
• Thermopile

Solution 26:
The increase in size of a body on heating is called thermal expansion.

Solution 27:
Linear expansion is the increase in length of a solid on heating.

Solution 28:
Coefficient of Linear expansion is equal to the change in length of a rod of length 1m when its temperature rises by 1°C.

Solution 29:
A bimetallic strip consists of two metal strips- one with high coefficient of expansion and the other with low coefficient of expansion.

Solution 30:
SI unit of coefficient of linear expansion is °C^-1.

Solution 31:
Water is the substance which contracts, when heated from 0°C to 4°C.

Solution 32:
Coefficient of volume expansion is equal to the change in volume of a rod of volume 1m³ when its temperature rises by 1°C.

Solution 33:
SI unit of coefficient of volume expansion is °C^-1.

Solution 34:
Two uses of bimetallic strip are

• As thermostat in electric iron
• As balance wheel in watches

Solution 35:
We should heat the neck of the bottle because due to heating the neck will expand and loosen the stopper stuck in the neck. In this way, we can easily remove the stopper from the bottle.

Solution 36:
When hot water is poured into a thick glass tumbler, it generally cracks because on pouring hot water in the tumbler the inner surface heats up and expands more as compared to its outer surface. This unequal expansion between the two surfaces causes a strain and the tumbler cracks.

Solution 37:
A substance is made up of molecules arranged in a lattice. On heating, the molecules vibrate faster in the lattice and bump into each other harder. So the distance between the molecules increases thus expanding lattice. Thus, the substances expand on heating.

Solution 38:
There are three types of thermal expansion

• Linear expansion
• Superficial expansion
• Cubical expansion

Solution 39:
Gaps are left in the railway tracks because the tracks gets heated during the day and as a result they increase in length. If the gaps are not provided, the railway line would buckle outward and may cause derailment.

Solution 40:
The beams of the bridges expand maximum during the summer days and contract maximum during the winter nights. If the beams are fixed at both ends on the pillars, they may develop crack due to expansion and contraction. To avoid this, beams are made to rest on rollers on the pillars to provide space for expansion.

Solution 41:

Solution 42:

Solution 43:

Solution 44:
A ventilator is provided in a room because it helps in removing the hot air from the room and allows the fresh and cold air to come in.

Solution 45:
No, it is not possible to heat a liquid or gas from above because the transfer of heat through convection takes place vertically upwards in liquids and gases. So if they are heated from above, the liquid or gas at the top will only be heated because most liquids and gases are themselves bad conductor of heat so they cannot conduct heat from top layer to the bottom layer.

Solution 46:

• Water is heated generally from below because water itself is a bad conductor of heat and the transfer of heat through convection take place vertically upwards.
• Land becomes warmer than water during the day because water has more specific heat capacity so it absorbs the heat and heats up slowly but on the other hand land has less specific heat and it heats up faster than water.

Solution 47:
Main characteristics of thermometric substance are

• The substance should have high coefficient of expansion so that it is sensitive to the smallest change in temperature
• The substance should have uniform expansion all over its entire volume
• The substance should have minimum specific heat so that it absorbs minimum heat from the body under measurement.

Solution 48:
Wood is an insulator of heat.

Solution 49:

• In cold countries, windows are provided with two glass panes because in between these two glass panes, a thin layer of air is present: air being a bad conductor obstructs the conduction of heat from the room to outside.
• 1 calorie = 4.2 joules
• Yes, it is possible to boil water in a thin paper cup because when heated the heat in the paper cup is transferred to the water through convection and paper cup doesn’t get sufficient heat to get burnt

Solution 50:
Thermometer works on the principle that substances expand on heating and contract on cooling. So we use a thermometric substance which expands and contracts uniformly.

Solution 51:
Advantages of mercury and alcohol as thermometric liquid are

• They both are good conductors of heat.
• They have high coefficient of expansion thus are sensitive to the smallest change in temperature
• Their freezing points are very low and boiling point is high in case of mercury

Disadvantages

• Alcohol is transparent and this makes hard to read the thermometer.
• It does not have uniform expansion.
• Mercury is less sensitive than alcohol as its coefficient of expansion is less than alcohol.
• Alcohol is a volatile liquid.

Solution 52:
Lower point of a thermometer is the temperature at which ice starts melting at normal atmospheric pressure i.e. 0°C
Upper point of a thermometer is the temperature at which water just starts boiling at normal atmospheric pressure i.e. 100°C.

Solution 53:

Solution 54:

• Laboratory thermometer is used to measure and observe the temperature of various chemical reactions
• Clinical thermometer is used to measure human body temperature
• Six’s maximum and minimum thermometer is used in meteorology and horticulture.

Solution 55:

Solution 56:
The temperature that is common in both clinical and Fahrenheit scale is -40°C
Derivation is as follows
Let the temperature be x
C/100= (F – 32)/180
x/100 = (x-32)/180
x * 180/100 = x-32
9/5 x = x – 32
-4/5 x =32
x = – 40

Solution 57:

• 60°C
  60/100 = (F-32) / 180
  F = 6 x 18 +32
  = 110°F
• 100°C
  100/100 = (F – 32) /180
  F = 180 x 1 + 32
  = 212°F
• -40°C
  -40/100 = (F – 32) /180
  F = -4 x 18 + 32
  = 40°F
• 85°C
  85/100 = (F – 32) /180
  F = 85 x 18/10 +32
  = 185°F

Solution 58:

• 104°F
  C = (F – 32) x 100/180
  C = 72 x 100/180
  = 40°C
• 95°F
  C = (F – 32) x 100/180
  = 63 x 10/18
  = 35°C
• 113°F
  C = (F – 32) x 100/180
  = 81 x 10/18
  = 45°C
• 32°F
  C = (F – 32) x 100/180
  = 0 x 10/18
  = 0°C

Solution 59:

Solution 60:
Three modes of heat transfer are

• Conduction involves the transfer of heat from the hot end to the cold end from particle to particle of the medium.
• Convection is the transfer of heat from one body to another by actual movement of the particles of the medium
• Radiation is the transfer of heat from one body to another without the need of an intervening material medium

Solution 61:

Solution 62:

Solution 63:
A wooden knob and a metal latch are both being at same temperature but it feels colder to touch the latch because metal is a good conductor and as soon as we touch it heat from our hand flows to the latch and we feel cold while on the other hand wood is a bad conductor of heat, heat of our hand does not flow into it therefore it does not feel cold.

Solution 64:
The flask consists of double walled glass container with vacuum between the walls A and B to prevent heat loss due to conduction and convection as vacuum is the excellent insulator .to prevent heat loss by radiation, the inner side of the wall A and outer side of wall B is silvered. It has a narrow mouth which is closed by a non-conducting rubber stopper.

Solution 65:
The spiral starts moving because due to the flame of the candle the spiral heats up and expands. While expanding, the spiral tries to create space for the extension in length and an outward pull is created which causes the spiral to move.

Solution 66:

• In winters, the human body covered with a blanket keeps warm because the blanket has air trapped in it which provide heat insulation to the body from the surroundings and keep us warm
• It is better to use two thin blankets to keep the body warm rather than using a single blanket of equal thickness because in between the two thin blankets there is more air trapped than in the single blanket of equal thickness so using two thin blankets better heat insulation is provided to the body from the surroundings and keep us warm
• In winter the birds fluff their feathers in order to trap air in their feathers so that the air provides heat insulation to their body from the surroundings and keep them warm and save them from winter.
• Old quilts are less warmer than new ones because the cotton in the old quilt gets compressed and very little air will remain trapped in it, hence heat insulation is quite poor
• People wear light colured clothes in winter because these clothes reflect most of the sun’s radiations and absorb only a little of them. Therefore, they keep themselves cool.

PAGE NO : 231
Solution 67:
Transformation of Sun’s energy in sun-eco system through a food chain is called energy flow.

Solution 68:

Solution 69:
Any energy transfer is not 100% because energy is lost to the surroundings in the form of heat, friction losses during the transfer of energy. Therefore complete energy is not transferred.

Solution 70:
Bio gas is produced by the action of bacteria on decaying organic matter. The primary source of bio gas in villages is dung of cow, or buffalo. The bio gas is mostly methane which can be used as a chief source of light and heat energy.

Solution 71:

Solution 72:

Solution 73:

Solution 74:

PAGE NO : 232
Solution 75:

Solution 76:
Water is not used as a thermometric liquid because It has low coefficient of expansion so it is less sensitive to temperature changes. Moreover, It is transparent thus making it difficult to read the thermometer and water evaporates with time thus producing error and also the freezing and boiling points are also low.

Solution 77:
The sensitivity of a thermometer can be increased by using a substance having high coefficient of expansion and uniform expansion so that its expands with the slightest change in temperature.

Solution 78:

• When hot water is poured into a thick glass tumbler, it generally cracks because on pouring hot water in the tumbler the inner surface heats up and expands more as compared to its outer surface. This unequal expansion between the two surfaces causes a strain and the tumbler cracks.
• Pyrex glass tumbler does not crack on adding hot water because Pyrex glass has low coefficient of expansion. It does not expand less when hot water is added to the tumbler.

Solution 79:

Solution 80:

Solution 81:

Solution 82:
Temperature in °C = 1°C
C/100 = (F-32)/180
F = 1 x 18/10 + 32
= 33.8°F

Solution 83:
Lower fixed point = 10°C
Upper fixed point =130°C
Range of thermometer= 130°C – 10°C = 120°C
No of divisions = 100
So least count = 120/100 = 1.2°C
On actual thermometer 40°C would have 40 divisions
So, on this thermometer it would show = 40 x LC = 48°C

Solution 84:
The green house is referred to a glass house. The heat enters the house but cannot escape out, because the glass reflects the heat back to the inside of the house. This makes glass house warmer than the outside environment. This phenomenon is called green house effect.

Solution 85:
Global warming occurs due to the presence of carbon di oxide, CFCs, methane in the atmosphere. Carbon dioxide acts as a transparent gas to incoming shortwave radiations which the earth re-radiates into space. It, therefore traps the outgoing radiations thus warming lower atmosphere of the earth thereby causing global warming.

Solution 86:
Harmful effects of global warming are

• The atmospheric temperature of earth would increase thereby making it difficult for a living being to survive
• It would melt down the polar caps thus increasing the size of the ocean and leading to floods, tsunami, etc.
• The increase in temperature would affect climate and rainfall thus affecting flora and fauna.
• Human beings would be vulnerable to diseases as microbes would get warmth to grow.

Solution 87:
The temperature in a green house rises because heat enters the house through the glass but cannot escape out, because the glass reflects the heat back to the inside of the house. This makes glass house warmer than the outside environment.

PhysicsChemistryBiologyMaths

Frank ICSE Solutions for Class 9 Physics – Fluids

PAGE NO: 157
Solution 1:
The thrust on the unit surface is known as pressure. The SI unit of pressure is Nm^-2.

Solution 2:
Pressure is given by
P = h X_p X_g.
Where h is height of liquid column, p is density of liquid, g is acceleration due to gravity.
Density of mercury is = 1.36 x 10⁴ kg/m³.
h= height of mercury column which is given = 75 cm = 0.75 m.
So pressure = 0.75 x 1.36 x 104 x 9.8 = 9.996 x 10⁴Nm^-2.

Solution 3:
Pressure is a scalar physical quantity.

Solution 4:
One pascal is defined as the pressure exerted on a surface of area 1 m² by a force of 1 Newton acting normally on the surface.

Solution 5:
The force acting normally on a surface is known as thrust.
SI unit of thrust is N.

Solution 6:

Solution 7:
Water can’t be used in place of mercury in a barometer because of its low density. It would require 10.34 m long tube to measure 1 atmospheric pressure which is not practically possible while mercury having high density (13.6 g/cc) would require only 0.76 m long pipe which is practically possible.

Solution 8:
Pressure is the physical quantity which is measured in bar.

Solution 9:
Thrust is a vector quantity.

Solution 10:
Thrust on a surface is the force acting normally on a surface while pressure on a surface is thrust acting on the unit area of a surface.

Solution 11:

Solution 12:
Lake has greater pressure at the bottom than the surface as pressure increases with depth. So when gas bubble is released at the bottom of the lake it experiences more pressure and is small in size but as it rises upwards the pressure experienced by it decreases. So it grows in size as it moves towards the surface from bottom.

Solution 13:
A dam has broader walls at the bottom than at the top because the pressure exerted by a liquid increases with its depth, and at any point at a particular depth liquid pressure is same in all directions. Now as more pressure is exerted by water on the wall of the dam as depth increases. Hence a thick wall is constructed at the bottom of dam to withstand greater pressure.

Solution 14:

Solution 15:
The pressure at a point in a liquid depends upon on the following three factors:

• It depends on the point below the free surface (h).
• It depends on density of liquid (p).
• It depends upon acceleration due to gravity (g) of the place.

Solution 16:

Solution 17:
A substance having a tendency to flow is called fluid.
A fluid exerts pressure on the bottom due to its weight and on the walls of the container in which it is enclosed by virtue of its ability to flow. This is called fluid pressure.

Solution 18:
The laws of liquid pressure are

• Pressure inside the liquid increases with the depth from the free surface of the liquid.
• Pressure is same at all points on a horizontal plane, in case of a stationary liquid.
• Pressure is same in all directions about a point inside the liquid.
• Pressure at same depth is different in different liquids. It increases with the increase in the density of the liquid.
• A liquid will always seek its own level.

Solution 19:

Solution 20:
A diving suit is a garment or device designed to protect a diver from the underwater environment.

Solution 21:
There are five main types of ambient pressure suits. These are wetsuits, drysuits, semidry suits, dive skins etc.

Solution 22:

Solution 23:
Manometer is a simple pressure gauge that measures differences in pressure at the two ends of the apparatus.
Manometer is a U shaped tube containing water whose one limb is dipped in vessel and vessel is tightly covered with plastic sheet. U shaped tube has two limbs one towards the vessel and other is opened to atmosphere.
Now if level of water toward atmospheric open limb is more than level of water in limb towards apparatus end then liquid is said to be at higher pressure than atmosphere. And if level of water toward atmospheric open limb is less than level of water in limb towards apparatus end then liquid is said to be at lower pressure than atmospheric pressure.

PAGE NO : 158
Solution 24:

Solution 25:
A hydraulic press works on the principle of pascal’s law. A hydraulic press can be used for extracting juice of sugarcane, sugar beet etc.

Solution 28:
Pascal’s law states that pressure applied to an enclosed liquid, is transmitted equally to every part of the liquid or in other words when pressure is applied at a point in a confined fluid, it is transmitted undiminished and equally in all directions throughout the liquid.
Hydraulic machines such as hydraulic press, hydraulic brakes and hydraulic jack are application of pascal’s law.

Solution 29:
Altimeter is a device which is used in an aircraft to measure its altitude.

Solution 30:
Atmospheric pressure decreases with increase in height. our atmosphere comprises of a large number of parallel layers. The pressure on a layer is equal to the thrust or weight of the gaseous column on the unit area of that layer. Hence, as we go up, the weight of the gaseous column decreases, which decrease the pressure of the gaseous column.

Solution 31:
Aneroid means containing no liquid and aneroid barometer is evacuated so it tends to collapse under the pressure of air. The stout spring balances the thrust on the metal box due to normal air pressure and prevents the box from collapsing. As this type of barometer doesn’t contain any liquid so it got its name aneroid barometer.

Solution 32:
Barometer is a device which is used for measuring atmospheric pressure. Barometers are used in weather forecasting and in measuring altitudes.

Solution 33:
Mercury is used in barometer because

• It can be obtained in pure form.
• It does not vaporizeat ordinary temperatures.
• Its density is high and hence the length of the mercury column supported by atmospheric pressure is 76 cm which is practically possible.

PAGE NO: 173
Solution 1:
All liquid exerts an upward force on the body placed in it. This Phenomenon is called buoyancy.

Solution 2:
The upward force which any liquid exerts upon a body placed in it is called the upthrust. The SI unit of upthrust is N.

Solution 3:
Buoyant force act on a body in upward direction.

Solution 4:
Upthrust is defined as the upward force on the object provided by the liquid because the object has displaced some of the fluid.

Solution 5:
When block of cork is immersed in water buoyant force acts on it in upward direction so to overcome this force we have to apply an equal force in downward direction to keep block of cork inside water.

Solution 6:
Wood has density less than water so volume of water displaced by it is more than the volume of wooden block submerged so force of upthrust is greater than the weight of wood which pushes wooden block on the surface. Hence, a piece of wood when left under water again comes to the surface.

Solution 7:
A body will weigh more in air as weight of body acts in downward direction and there is no force in upward direction while body submerged in water weigh less because an upthrust act on the body in upward direction so the resultant weight of the body decreases.

Solution 8:
Upthrust or buoyant force depends on the following factors:

• Volume of body submerged in the liquid.
• Density of the liquid.
• Acceleration due to gravity.

Solution 9:

Solution 10:
Weight of the body in air = 300 gf.
Apparent Weight of the completely immersed body in water = 280 gf.

• Loss in weight of the body = Weight of body in air – apparent weight of immersed body.
  Loss in weight = 300 gf – -280 gf = 20 gf.
• As upthrust on the body = loss in weight
• So uptrust = 20 gf.

Solution 11:
Edge of metal cube = 5 cm.
Density of the metal cube = 9 gcm^-3 = 9 x 10³ kgm^-3.
Volume of the metal cube = 125 cm³ = 125 x 10^-6 m³.
Mass of the metal cube =9 x 10³ x 125 x 10^-6 = 1125 x 10^-3 =1.125 kg.
Weight of the liquid = mass x gravity = 1.125 x 10 = 11.25 N.
Density of liquid = 1.2 gcm^-3= 1.2 x 10³ kgm^-3.
Upthrust of the liquid = V X_p X_g.
Upthrust = 125 x 10^-6 x 1.2 x 10³ x 10 = 1.5 N.
Apparent weight of the body = weight of liquid – upthrust
Apparent weight = 11.25 N – 1.5 N = 9.75 N
Tension in the string is equal to the apparent weight of the body
So, tension in string would be 9.75 N.

Solution 12:
It is easier to lift a heavy stone under water because in water an upthrust acts on the upward direction which reduces the apparent weight of the stone and makes it easy to lift.

Solution 13:
Principle of Archimedes’ states that when a body is totally or partially immersed in a fluid, it experiences an upthrust equal to the weight of the fluid displaced by it.

Solution 14:

Solution 15:

PAGE NO : 174
Solution 16:
Wood has density less than water so volume of water displaced by it is more than the volume of wooden block submerged so force of upthrust is greater than the weight of wood which makes it float on the water surface. And the apparent weight of the piece of the wood would be zero.

Solution 17:
Density of iron is less than the density of mercury so it will float on the surface of the mercury. Apparent weight of the floating iron ball is zero.

Solution 18:
Iron nail has density less than that of mercury so it will float on the surface of mercury but in the case of water it will sink because the density of iron nail is more than that of water.

Solution 19:
No, the relative density of a substance is the ratio of the density of the substance to the density of water at 4⁰C.

Solution 20:

• SI unit of buoyant force is N.
• SI unit of density is Kgm^-3.
• SI unit of weight of body is N.
• Relative density is a pure ratio it has no dimension.

Solution 21:
Density of iron is more than the density of water so it sinks down in the water but in case of ship, it is design in such a manner that it encloses large quantity of air in air tight bags and in rooms and corridors which makes the average density of ship less than that of water and ship floats on the surface of the water.

Solution 22:
The fractional part submerged equals the ratio of the density of the material of the block to the density of the liquid.
(Density of floating body / Density of liquid) = fraction submerged.
The Fraction of ice submerged in water remain same as density of ice and water remain same during melting. As ice melts some volume of ice decrease and convert into water and volume of water increase by same amount. So, level of water remains same during melting.

Solution 23:
The fractional part submerged equals the ratio of the density of the material of the block to the density of the liquid.
(Density of floating body / Density of liquid) = fraction submerged.
Height of wooden piece = 15 cm.
Height of wooden piece sinks in water = 10 cm.
Fraction of wooden piece submerged in water = 10/15 = 0.67.
As liquid is water so ratio of Density of wooden by density of water gives relative density of floating wooden piece. So, relative density of wooden block is 0.67.
Height of wooden piece = 15 cm.
Height of wooden piece sinks in spirit = 12 cm.
Fraction of wooden piece submerged in water = 12/15 = 0.8.
We know density of wooden piece = 0.67
(Density of floating body / Density of liquid) = fraction submerged.
Density of liquid/spirit = (Density of floating body /fraction submerged)
Density of liquid/spirit = 0.67/0.8 = 0.83.
Relative density of spirit is 0.83.

Solution 24:

• When a body is completely immersed in water then it displaces equal volume of water to its own weight. Volume of body of man is same in both river and sea so weight of water of sea displaced by him is equal to the weight of water of river displaced by him. And ratio of weights would be 1:1.
• Sea water contains mineral salts and density of sea water increase due to presence of these. As density of sea water is more than the normal water so it apply more buoyant force than usual one and a person find it easy to swim in sea water.

Solution 25:
The fractional part submerged equals the ratio of the density of the material of the block to the density of the liquid.
(Density of floating body / Density of liquid) = fraction submerged.
Fraction of wooden piece submerged in water = 2/3 = 0.67.
As liquid is water so ratio of Density of wooden by density of water gives relative density of floating wooden piece.
So, relative density of wooden block is 0.67.
Density of water in SI system = 1000 Kg m^-3.
Density of wood=relative density x density of water =0.67 x 1000 Kg m^-3 =670 kgm.
Fraction of wooden piece submerged in oil = 3/4 = 0.75.
We know density of wooden piece = 0.67
(Density of floating body / Density of liquid) = fraction submerged.
Relative Density of oil = (Relative Density of wooden block/fraction submerged)
Density of oil = 0.67/0.75 = 0.893.
Density of water in SI system = 1000 Kg m^-3.
Density of oil =relative density x density of water =0.893 x 1000 Kg m^-3 =893 kgm^-3.

Solution 26:
Relative density of Ice = 0.92
Relative density of sea water = 1.025
Let total volume of iceberg = X cm³.
Volume of iceberg above water = 800 cm³.
Volume of iceberg in submerged in the water = (X – 800) cm³.
Fraction of iceberg submerged = (X- 800)/X
Now we know that fractional part submerged equals the ratio of the density of the material of the block to the density of the liquid.
(Density of ice / Density of sea water) = fraction submerged
0.92/1.025 = (X-800)/X
0.8975 X = X – 800
X – 0.8975 X = 800
0.1025 X = 800
X = 800/0.1025 = 7804.8 cm³.
Total volume of iceberg = 7804.8 cm³.

Solution 27:
Relative density of wax = 0.95
Relative density of brine = 1.1
(Density of wax/ Density of brine) = fraction submerged
0.95/1.1 = fraction of volume submerged
Fraction of volume submerged = 0.86

Solution 28:
Relative density of Ice = 0.9 cm
Relative density of sea water = 1.1 cm
(Density of ice / Density of sea water) = fraction submerged of iceberg
0.9/1.1 = fraction of iceberg submerged
Fraction of iceberg submerged = 9/11.

Solution 30:
Lactometer is commonly used for testing the purity of milk.

Solution 31:
Density of water at 4⁰c in SI system is = 1000 Kgm^-3.

Solution 32:
Side of wooden cube = 10 cm.
Volume of wooden cube = 10 x 10 x 10 = 1000 cm³.
Mass of wooden cube = 700 g.
Density of wooden cube = mass/volume = 700/1000 = 0.7 gcm^-3.
Density of water = 1 gcm^-3.
(Density of floating body / Density of liquid) = fraction submerged
0.7/1 =fraction submerged
Fraction of wooden cube submerged in water = 0.7
Height of wooden cube = 10 cm
Part of wooden cube which is submerged = 10 x 0.7 = 7 cm
So, wooden cube will float in water with 3 cm height above the water surface.

Solution 33:
Volume of wooden block = 0.032 m³.
Mass of wooden block = 24 Kg.
Density of wooden block = mass/volume = 24/0.032 = 750 Kgm^-3.
Density of water = 1000 Kgm^-3.
(Density of floating body / Density of liquid) = fraction submerged
750/1000 =fraction submerged
Fraction of wooden block submerged in water = 0.75
Total volume of wooden block = 0.032 m³.
Part of volume of wooden block which is submerged = 0.032 x 0.75 = 0.024 m³.

Solution 34:
Relative density = density of substance /density of water at 4⁰C.
As relative density of platinum is 21.50, this means platinum is 21.5 times denser than water at 4⁰C.

PAGE NO : 175
Solution 35:
Density of mercury = 13600 Kgm^-3.
Density of water at 4⁰C = 1000 kg m^-3.
Relative density = density of substance /density of water at 4⁰C.
Relative density of mercury = 13600 Kgm^-3/1000 kg m^-3 = 13.6.

Solution 36:
volume of body = 100 cm³.
Weight of body = 1 kgf = 1000 gf
Mass of body= 1000 gm.
Density of liquid = 1000 gm/100cm³ = 10 gcm³.
Density of water at 4o = 1gcm^-3.
Relative density = density of substance /density of water at 4⁰ C
Relative density = 10 gcm³ /1 gcm³ = 10
Mass of body= 1000 gm.
Density of water = 1 gcm^-3
Acceleration due to gravity = 10 ms^-2.
Upthrust = V X_p X_g.
Upthrust = 100 x 1 gf = 100 gf.
Resultant weight of the body = weight – upthrust = 1000 gf – 100 gf = 900 gf.

Solution 37:
When a body is completely immersed in water then it displaces equal volume of water to its own weight.
So, volume of body = 20000 cm³.
Mass of body = 70 kg = 70000 gm
Density of body = mass /volume = 70000/20000= 3.5 gm cm^-3.
Density of water in C.G.S system = 1g cm^-3.
Relative density of body = density of body /density of water =3.5 gm cm^-3/1g cm^-3.
Relative density = 3.5.

Solution 38:
Relative density = density of mercury /density of water.
Density of mercury = relative density x density of water.
Relative density = 13.6.
Density of water in C.G.S system = 1g cm^-3.
So, density of mercury in C.G.S system = 13.6 x 1 = 13.6 gcm^-3.
Density of water in SI system = 1000 Kg m^-3.
So, density of mercury in SI system = 13.6 x 1000 = 13.6 x 10³ Kgcm^-3.

Solution 39:
Density of iron is = 7.8 x 10³ Kg m^-3.
Density of water at 4⁰C = 10³ Kg m^-3.
Relative density of a substance is the ratio of the density of the substance to the density of water at 4⁰C.
So, relative density of iron is = 7.8 x 10³ Kg m^-3/103 Kg m^-3 = 7.8

Solution 40:

• Mass of a metallic piece remains unchanged with increase in temperature.
• Volume of metallic piece increases with increase in temperature.
• Density of metallic piece decreases with increases in temperature.

Solution 41:
Density of water decreases with the increase in temperature and increases with decreases in temperature.

Solution 42:

PAGE NO: 177
Solution 1:
All liquid exerts a upward force on the body placed in it. This Phenomenon is called buoyancy.

Solution 2:
The upward force which any liquid exerts upon a body placed in it is called the upthrust.

Solution 3:
Pressure is a scalar quantity.

Solution 4:
Thrust is a vector quantity.

Solution 5:
SI unit of density is Kgm^-3.

Solution 6:
The relative density of a substance is the ratio of the density of the substance to the density of water at 4⁰C.

Solution 7:

Solution 8:
Principle of Archimedes’ states that when a body is totally or partially immersed in a fluid, it experiences an upthrust equal to the weight of the fluid displaced. Yes, it applies to gases also.

Solution 9:
Thrust on a surface is the force acting normally on a surface while pressure on a surface is thrust acting on the unit area of a surface.

Solution 10:
Pascal’s law states that pressure applied to an enclosed liquid, is transmitted equally to every part of the liquid or in other words when pressure is applied at a point in a confined fluid, it is transmitted undiminished and equally in all directions throughout the liquid.

Solution 11:
Yes, all liquid exert pressure.

Solution 12:
Hydraulic machines such as hydraulic press, hydraulic brakes and hydraulic jack are application of pascal’s law.

Solution 13:
Pascal’s law is principle of hydraulic machines.

Solution 14:
Brahma press depends upon Pascal’s law.

Solution 15:

• A hydraulic press can be used for extracting juice of sugarcane, sugar beet etc.
• A hydraulic press can be used for pressing cotton bales, quilts, books etc.

Solution 16:
Atmospheric point at any point in air at rest is equal to the weight of a vertical column of air on a unit area surrounding the point, the column extending to the top of atmosphere.

Solution 17:
Atmospheric pressure at sea level is about 10⁵ N/m².

Solution 18:
Barometer is used for measuring the atmospheric pressure.

Solution 19:
Altimeter is a device which is used in an aircraft to measure its altitude.

Solution 20:
A falling barometer indicates the approach of rain or storm or both.

PAGE NO : 178
Solution 21:
A atmospheric pressure diving suit is a garment or device designed to protect a diver from the underwater environment. Yes, diving suits create buoyancy.

Solution 23:
A fluid exerts pressure on the bottom due to its weight and on the walls of the container in which it is enclosed by virtue of its ability to flow. This is called fluid pressure.

Solution 24:
A dam has broader walls at the bottom than at the top because the pressure exerted by a liquid increases with its depth, and at any point at a particular depth liquid pressure is same in all directions. Now as more pressure is exerted by water on the wall of the dam as depth increases. Hence a thick wall is constructed at the bottom of dam to withstand greater pressure.

Solution 25:
Pascal’s law states that pressure applied to an enclosed liquid, is transmitted equally to every part of the liquid.
Means when pressure is applied at a point in a confined fluid, it is transmitted undiminished and equally in all directions throughout the liquid.

Solution 27:
Factors which affect the atmospheric pressure as we go up are

• Weight of gaseous column.
• Density of gaseous column.

Solution 28:
Atmospheric pressure decreases with increase in height. Our atmosphere comprises of a large number of parallel layers. The pressure on a layer is equal to the thrust or weight of the gaseous column on the unit area of that layer. Hence, as we go up, the weight of the gaseous column decreases, which decrease the pressure of the gaseous column.

Solution 29:
Barometer is a device used for measuring atmospheric pressure.
Simple barometer has two main defects

• It is not suitable for making accurate measurement of atmospheric pressure as any change in the level of mercury in the tube changes the level of the free surface of mercury is trough and fixed scale cannot be used with it.
• Simple barometer is not portable. So, it cannot be used by airmen, navigators, mountaineers, who need a portable barometer.

Solution 31:
We don’t feel uneasy even under enormous pressure of the atmosphere above us because our blood also exerts a pressure called blood pressure, which is greater than atmospheric pressure. So, there is balance between our blood pressure and atmospheric pressure.

Solution 32:
Reading of a barometer would rise if it is taken to the mine as pressure increases with depth.
Reading of a barometer would fall if it is taken to a hill as pressure decreases with increase in height.

Solution 33:
Weight of solid in air = 2.10 N
Relative density of solid = 8.4
Now, Relative density = weight of solid in air/ loss of weight of solid in water.
Loss of weight of solid in water = weight of solid in air/ Relative density.
Loss of weight of solid in water = 2.10/8.4 = 0.25 N.
Weight of solid in water = weight in air – loss of weight in water
Weight of solid in water = 2.10 – 0.25 =1.85 N.
Relative density of liquid =1.2
We know
Relative density of liquid = Loss of weight of solid in liquid/loss of weight of solid in water.
Loss of weight of solid in liquid = Relative density x loss of weight of solid in water.
Loss of weight of solid in liquid = 1.2 x 0.25 = 0.3 N.
Weight of solid in liquid = weight of solid in air – loss of weight of solid in liquid.
Weight of solid in liquid = 2.10 – 0.3 = 1.8 N.

Solution 34:
Density of iron is 7800Kgm^-3.
This means a cube of iron having side 1m would weigh 7800 Kg.
Density of water at 4⁰C is 1000 Kgm^-3.

Solution 35:
Relative density of body = 0.52
Density of water at 4⁰C = 1000 Kgm^-3.
Density of body = 0.52 x 1000 Kgm^-3= 520 Kgm^-3
We know density = mass x volume.
Mass = density x volume
Mass = 520 x 2 =1040 Kg.
Mass of given body is 1040 Kg.

Solution 36:
Piece of metal weighs in air = 44.5 f
Piece of metal weighs in liquid = 39.5 f.
Loss of weight of metal in liquid = 44.5 – 39.5 = 5f.
Relative density = weight of solid in air/ loss of weight of solid in water.
Relative density of liquid =44.5f/5f =8.9
Relative density of liquid = 8.9

Solution 37:

Solution 38:
Principle of floatation states that a floatating body displaces an amount of fluid equal to its own weight.
Ship is designed in such a manner that it encloses large quantity of air in air tight bags and in rooms and corridors which makes the average density of ship less than that of water.

Solution 40:
Acid battery hydrometer is used to check the concentration of sulphuric acid in an acid battery.

Solution 41:
Iron nail has density less than that of mercury so it will float on the surface of mercury but in the case of water it will sink because the density of iron nail is more than that of water.

Solution 43:

Solution 44:

• A balloon filled with hydrogen has low density than air so it rises over the air but as height increases density of air decreases and at a certain height the density of hydrogen in balloon and density of air become equal. And as there is no density difference there is no pressure difference also and hence balloon stops rising further.
• Density of egg is greater than fresh water so it sinks in fresh water but due to addition of salt density of water increases which makes the density of salt water greater than egg and hence floats in a strong solution of salt.
• The bottom of the hydrometer is made heavier by loading it with lead shots so that it floats vertically with some of its portion outside the surface of water in the jar.
• Relative density of Ice is = 0.9 cm^-3
  Relative density of sea water is = 1 cm^-3
  (Density of ice / Density of sea water) = fraction submerged of iceberg
  0.9/1 = fraction of iceberg submerged
  Fraction of iceberg submerged = 9/10.

Thus in colder countries where there are icebergs in oceans, only about 1/10 is seen above water and the remaining water 9/10 remain submerged. Hence, there is danger of these icebergs to the ships sailing in these oceans.

Solution 45:

Solution 46:

Solution 47:

Solution 48:

Solution 49:

Solution 50:

Solution 51:

PhysicsChemistryBiologyMaths

Frank ICSE Solutions for Class 9 Physics – Laws of Motion

PAGE NO: 113
Solution 1:
The property by which a body neither changes its present state of rest or of uniform motion in a straight line nor tends to change the present state is known as inertia.

Solution 2:
A book lying on a table will remain placed at table unless it is displaced by some external force. This is an example of inertia of rest.
A ball rolling on the ground will continue to roll unless the external force , the force of friction between the ball and the ground stops it.

Solution 3:
The greater is the MASS , the greater is the inertia of the object

Solution 4:
An object possess two kind of inertia, inertia of rest and inertia of motion.A book lying on a table will remain placed at table unless it is displaced by some external force. This is an example of inertia of rest.
A ball rolling on the ground will continue to roll unless the external force , the force of friction between the ball and the ground stops it.

Solution 5:
1 Newton is the force which when applied to a body of unit mass produces a unit acceleration in it. 1 newton would produce acceleration of 1 ms^-2 in a mass of 1 kg.

Solution 6:
The acceleration produced bya force in an object is directly proportional to the applied FORCE and inversely proportional to the MASS of the object.

Solution 7:
SI unit of force is Newton (N).

Solution 8:
Acceleration is the physical quantity associated with N kg^-1.

Solution 9:
1 N = 10⁵ Dyne.

Solution 10:
As mass of loaded van is greater than sports car so it would require more force to stop.

Solution 11:
We know force = mass x acceleration.
a= f/m = 12 N / 4 kg. = 3 ms^-2
so acceleration of the body would be 3 ms^-2.

Solution 12:
SI unit of force is Newton whereas CGS unit of force is dyne.
1 newton / 1dyne = 10⁵.

Solution 13:
SI unit of momentum is kgms^-1.

Solution 14:
Momentum is defined as the amount of motion contained in the body. It is given by the product of the mass of the body and its velocity.

Solution 15:
Momentum is the physical quantity associated with the motion of the body.

Solution 16:
Momentum is possessed by bodies in MOTION.

Solution 17:
A fast pitched soft ball has more momentum.

Solution 18:
SI unit of momentum is kgms^-1 and CGS unit of momentum is g cms^-1.
And their ratio is = 1000 x 100 gms^-1= 1:10.

Solution 19:
A body at rest has zero momentum as its velocity is zero.

Solution 20:
According to Newton’s third law, for every action there is always an equal and opposite reaction.

Solution 21:
When a force acts on a body then this is called an action.

Solution 22:
No, action and reaction never act on a same body they always act simultaneously on two different bodies.

Solution 23:
2nd law of motion gives the definition of force.

Solution 24:
Newton’s third law explains this statement.

Solution 25:
Force is a vector quantity.

Solution 26:
This means these forces are balanced forces.

Solution 27:
Passengers tend to fall sideways when the bus takes a sharp turn due to the inertiaof direction.

Solution 28:
Passengers are thrown in the forward direction as the running bus stops suddenly because due to their inertia of motion, their upper body continues to be in the state of motion even though the lowerbody comes to rest when the bus stops.

Solution 29:
Passengers tends to fall in backward direction when bus starts suddenly because due to their inertia of rest, as soon as the bus starts, their lower body comes in motion but the upper body continues to be in the state of rest.

Solution 30:
No, internal forces cannot change the velocity of a body.

Solution 31:
When a hanging carpet is beaten using a stick, the dust particles will start coming out of the carpet because the part of the carpet where the stick strikes, immediately comes in motion while the dust particle sticking to the carpet remains at rest . Hence a part of the carpet moves ahead alongwith the stick, and the dust particles fall down due to the earth’s pull.

Solution 32:
When we shake the branches of a tree, the fruits and leaves remain in state of rest while branches comes in rest so fruits and leaves are detached from the tree.

Solution 33:
We know force = mass x acceleration
F₁ = 10 x 5 = 50 dyne.
F₂ = 20 x 2 = 40 dyne.
So first body require more force.

Solution 34:

PAGE NO : 114
Solution 35:
initial velocity of the object = 0 ms^-1
Acceleration of the object = 8 ms^-2.
Time = 5 s.
Distance covered would be S = ut + 1/2 at².
S = 1/2 x 8 x 5 x 5 = 100 m.

Solution 36:
Initial velocity of the truck = 0 ms^-1
Distance covered by truck = 100 m
Time taken to cover this distance = 10 s.
We know Distance covered would be S = ut + 1/2 at².
100 =1/2 x a x 100
a= 2 ms^-2.
Mass of truck = 5 metric tons = 5000 kg.
Force acted on truck = mass x acceleration
Force = 5000 x 2 = 10000 N.

Solution 37:
Momentum is used for quantifying the motion of body.

Solution 38:
When we fire a gun, a force is exerted in the forward in the forward direction as the bullets comes out; in reaction to which an equal and opposite force is act in the backward direction and hence, we feel a backward jerk on the shoulder.

Solution 39:
A person applies force on water in backward direction and water according to third law of motion water apply an equal and opposite force in forward direction which helps a person to swim.

Solution 40:
Newton’s third law of motion is involved in the working of a jet plane.

Solution 41:
Yes, a rocket can propel itself in a vacuum once it is given initial velocity.

Solution 42:
Action is equal and opposite to reaction but they act on different bodies and object moves as movement requires an unbalanced force and these are provided once inertia is overcome.

PAGE NO: 125
Solution 1:
Sir Isaac Newton stated the law of gravitation.

Solution 2:
Every object in the universe attracts every other object with a force directly proportional to the product of their masses and inversely proportional to the square of distance between them.

Solution 3:
Gravity is the force of attraction between the object and the earth whereas gravitation refers to the force of attraction that exists between any two bodies that possess mass.

Solution 4:
Acceleration due to gravity is the acceleration experienced by a body during free fall.

Solution 5:
g = GM/R².

Solution 6:
We know that law of gravitation.
F = G ( m₁ x m₂)/R².
Here G is universal constant and is called constant of gravitation. It doesnot depend upon on the value of m₁, m₂ or R.
Its value is same between any two objects in the universe.

Solution 7:
SI unit of constant of gravitation is Nm²kg^-2.

Solution 8:
we know that law of gravitation.
F = G ( m₁ x m₂)/R².

• If distance between them is halved then put R = R/2.
  F = 4 x G( m₁ x m₂)/ R².
  F₁ = 4 F.
• If distance between them is doubled then put R = 2R.
  F = G( m₁ x m₂)/ 4R².
  F₁ = F/4.
• If distance between them is made four times then put R = 4R.
  F = G( m₁ x m₂)/16 R².
  F₁ = F/16.
• If distance between them is infinite then put R = infinite.
  F = G( m₁ x m₂)/ R².
  F₁ = 0.
• If distance between them is almost zero then put R = 0.
  F = G( m₁ x m₂)/ 0.
  F₁ = infinite.

Solution 9:
All objects in the universe attract each other along the line joining their CENTRES.

Solution 10:
The force of attraction between any two material objects is called FORCE OF GRAVITATION.

Solution 11:
The gravitational force of the earth is called earth’s GRAVITY.

Solution 12:
The Gravity is a particular case of GRAVITATIONAL FORCE OF EARTH.

Solution 13:
The value of G is extremely SMALL.

Solution 14:
Yes the law of gravitation is also applicable in case of the sun and moon.

Solution 15:
we know that law of gravitation.
F = G ( m₁ x m₂)/R².
Mass of earth = 6 x 10²⁴kg.
Mass of the person = 100 kg.
G = 6.7 x 10-11 Nm²kg^-2.
Radius of earth = 6.4 x 10¹⁴.
F = (6.7 x 10^-11 x 100 x 6 x 10¹⁴ )/ (6.4 x 6.4 x 10¹²) = 981.4N
Force of gravity due to earth acting on a 100 kg person is 981.4 N.

Solution 16:
Objects fall towards the earth due to force of gravitation.

Solution 17:
Because the masses of persons are not large enough to overcome the value of small constant of gravitation so the force of gravitation is very small and negligible to feel.

Solution 18:
Initial speed of ball is = 4.9 ms^-1.
Acceleration due to gravity = -9.8 ms^-2.

• We know v² – u² =2as
  At highest point final velocity is zero so
  0 – 4.9 x 4.9 = 2 x (-9.8) S
  S = 1.125 m
• We know v = u + at
  0 = 4.9 – 9.8 t
  T = 0.5 sec.
• for highest point initial velocity is zero
  Acceleration due to gravity is = 9.8 ms^-2.
  Final velocity at ground is v
  V² – 0 = 2 x 9.8 x 1.125
  V = 4.9 ms^-1.

Time taken to reach ground from highest point
V = u + at
4.9 = 0 + 9.8 t
T = 4.9/9.8 = 0.5 sec.
So time of ascent is equal to time descent.

Solution 19:
g = GM/R².

Solution 20:
Value of the g at the surface of the earth is 9.8ms^-2.

Solution 21:
Mass of the body is constant at all positions so mass will not change. But weight will change as gravity on the surface of earth is almost 6 times than on the surface of the moon, so its weight will increase almost 6 times on the surface of earth.

Solution 22:
We will weigh more on the surface of the earth.

Solution 23:
Beam balance is used to measure the mass of a body.

Solution 24:
Spring scale is used to measure the weight of a body.

Solution 25:
The weight is greater at the poles than the equator.

Solution 26:
Newton 1N = 9.8 kgwt.

Solution 27:
We will weigh more on earth surface as value of g is greater on earth surface.

Solution 28:
No, the force of gravitation between two objects does not depend on the medium between them.

Solution 29:
we know that law of gravitation.
F = G ( m₁ x m₂)/R².
Now m₁ = 2 m₁
m₂ = 2 m₂
R = 2 R
F₁ = G ( 2m₁ x 2m₂)/4R².
F₁ = F
So force between them remains same.

PAGE NO : 126
Solution 30:
Yes, in absence of gravity all freely falling body have same force acting on them.

Solution 31:
g= GM/R²
it means acceleration due to gravity is directly proportional to the mass of body and inversely proportional to the square of distance between earth and object.

Solution 35:
Yes a body falling freely near the earth surface has a constant acceleration.

Solution 36:
As we know
g= 1/R²
so value of g is more at poles than equator so value of g is maximum near a camp site in Antarctica as this lie on the pole.

Solution 37:

PAGE NO: 128
Solution 1:
Force is that external agency which tends to change the state of rest or the state of motion of a body.

Solution 2:
1 Newton is the force which when applied to a body of unit mass produces a unit acceleration in it.

Solution 3:
Newton is the SI unit of force whereas dyne is the CGS unit of force.
1 N = 10⁵ dyne.

Solution 4:
No, force is a vector quantity.

Solution 5:
A force can produce MOTION in an objectat rest. It can ACCELERATE an object and can change its DIRECTION of motion.

Solution 6:

• force changes the shape of skin.
• force produces stretching in the rubber.
• force provides retardation to the car and finally stops the car.
• force decreases the momentum of ball and finally stops the ball.

Solution 7:
No, every force does not produce motion in every type of body.

Solution 8:
The amount of inertia of a body depends on its MASS.

Solution 9:
You can change the direction in which an object is moving by APPLYING FORCE ON IT.

Solution 10:
A man riding on a car has INERTIA of motion.

Solution 11:
When a body is at rest , it will continue to remain at rest unless some external force is applied to change its state of rest. This property of body is called inertia of rest.

Solution 12:

• Weight of the book is action and normal force applied by table on book is reaction.
• Force applied by man on ground is action and force of friction is the reaction.
• Force applied by hammer on nail is action and normal force applied by nail on hammer is reaction to this force.
• Firing of bullet is the action and recoiling of gun is the reaction.
• Force applied by us on wall is action and opposite force applied by wall on us or we can say that resistance of wall to our force is reaction.

Solution 13:
A book lying on a table will remain placed on table unless it is displaced by some external force. This is an example of inertia of rest.
A ball rolling on the ground will continue to roll unless the external force , the force of friction between the ball and the ground stops it.This is an example of inertia of motion.

Solution 14:
Unbalance external force causes motion in the body.

Solution 15:
Linear Momentum is defined as the amount of motion contained in a body. It is given by the product of the mass of the body and its velocity.

Solution 16:
SI unit of momentum is kgms^-1.

Solution 17:
According to Newton’s first law force is that external agency which tends to change the state of rest or the state of motion of a body.

Solution 18:
According to Newton’s first law, everybody continues in its state of rest or in uniform motion in a straight line unless compelled by some external force to act otherwise.

PAGE NO : 129
Solution 19:
Out of all these, as mass of truck is greatest and mass is measure of inertia so a truck has maximum inertia.

Solution 20:
It is advantageous to run before taking a long jump because after running we get motion of inertia which helps in long jumping.

Solution 21:
Ball moving on a table top stops eventually due to force of friction between the ball surface and table surface.

Solution 22:
Force is equal to the rate of change of linear momentum.

Solution 23:
According to newton second law of motion, when a force acts on a body, the rate of change in momentum of a body is equal to the product of mass of the body and acceleration produced in it.
Yes, Newton’s first law is contained in the second law as if force is zero then acceleration would be zero which means body would remain in its state of rest or in state of constant motion.

Solution 24:
1 Newton is the force which when applied to a body of unit mass produces a unit acceleration in it.
1 newton / 1dyne = 10⁵.

Solution 25:
1 newton = 1 kg x 1 ms^-1 = 1000 g x 100 cms^-1 = 10⁵ cms^-1.
1 dyne 1 g x 1 cms^-1 = 1cms^-1.
So 1 newton = 10⁵ dyne.

Solution 26:
No, the body will not move as the two forces are equal and opposite and they constitute balanced forces.

Solution 27:
As these forces are balanced so they will not affect the motion and motion of the body will remain unaffected.

Solution 28:
According to Newton’s third law, for every action there is always an equal and opposite reaction. Rocket works on the same principle. The exhaust gases produced as the result of the combustion of the fuel are forced out at one end of the rocket. As a reaction , the main rocket moves in the opposite direction.

Solution 29:
According to Newton’s third law, every action has equal and opposite reaction so force exerted by the wall on the boy is 30 N.

Solution 30:
Newton stated the law of inertia.

Solution 31:
Every object in the universe attracts every other object with a force directly proportional to the product of their masses and inversely proportional to the square of distance between them.
Law of gravitation is called universal because it applies to all bodies of universe.

Solution 32:
Gravity is the force of attraction betwen the object and the earth whereas gravitation refers to the force of attraction that exists between any two bodies that possess mass.

Solution 33:
Person will weigh more at Delhi as we know that gravity decreases with increase in height. Now as Shimla is at a height from Delhi so weight is less in Shimla and more in Delhi.

Solution 34:
Spring scale is used to measure the weight of a body.

Solution 35:
Gravity is another kind of FORCE. It exerts all through the UNIVERSE. The sun’s gravity keeps the PLANETS in their orbits. Gravity can only be felt with very large MASS.

Solution 36:

• Objects fall on the earth due to gravitational force between the earth and object.
• Atmosphere doesnot escape because molecules of atmosphere are attracted by earth due to gravitational force of earth.
• A moon rocket needs to reach a certain velocity because during its motion earth attracts the rocket towards it by its gravitational force.

Solution 37:
‘g’ is acceleration due to earth’s gravity and ‘G’ is universal gravitational constant.

Solution 38:
Free fall means motion of a body under the gravity of earth only.

Solution 39:
Yes, we have a gravitational force of attraction between us and a book. But our mass is very small so the force between us and book is very small almost negligible.

Solution 40:
Yes, the force of gravitation of earth affects the motion of moon, because moon is revolving around earth and centripetal force for this revolution is provided by earth’s gravitation.

Solution 41:
Inertial mass is measure of inertia of the object. According to second law of motion F = m x a
m= F/a and this mass is called as inertial mass.
Newton law of gravitation gives another definition of mass.
F = (G m₁m₂)/R²
Thus m₂ is the mass of the body by which another body of mass m1 attracts it towards it by law of gravitation. This mass is called gravitational mass.

Solution 42:
Newton law of gravitation is that Every object in the universe attracts every other object with a force directly proportional to the product of their masses and inversely proportional to the square of distance between them.

• Gravity is the force of attraction between the object and the earth whereas gravitation refers to the force of attraction that exists between any two bodies that possess mass.
• ‘g’ is acceleration due to earth’s gravity and ‘G’ is universal gravitational constant.

Solution 43:
Yes, it is true that apple attracts the earth towards it with same force but the mass of earth is so huge that acceleration produced in it due to this force is very much small and negligible to notice.

Solution 44:
we know that law of gravitation is
F = G ( m₁ x m₂)/R²
Here the F is force due to attraction and this force is equal to weight of the body m2g.
So m2g = G ( m₁ x m₂)/R²
g= (G x m₂)/R².
Here R is the distance between earth centre and the object centre. Now if we go on higher altitude say ‘H’ then this R would increase to (R + H)
And value of gravity at height H becomes
g’= (G x m₂)/( R +H)².
As denominator increases so g’ would be less than g and hence we can say that gravity decreases on higher altitudes.

Solution 45:

• The force exerted by the block on is the weight of box and that is equal to 20N.
• The force exerted by string on block is equal to the tension in the string and this is also equal to the 20N.

Solution 46:
we know F = m x a
m= F/a
so we can calculate mass of each body
Mass of body 1 m₁ = 4/8 = 0.5 kg.
Mass of body 2 m₂ = 4/20 = 0.2 kg.
Total mass when two masses are tied together M = 0.5 + 0.2 = 0.7 kg.
Now as force is acting on total mass so acceleration produced is
a= 4/0.7 = 5.71 ms^-2.

PAGE NO : 130
Solution 47:

Solution 48:
Initial speed of body = 5 ms^-1
Final speed of body = 8 ms^-1
Time taken to acquire this speed = 2s.
Acceleration of body = ( v- u)/t
a= (8- 5)/2 = 1.5 ms^-2.
Force applied on body = 0.9 N.
we know F = m x a.
m = f/a = 0.9/1.5 = 0.6 kg
mass of the body is 600 gm.

Solution 49:

Solution 50:
The force that acts on a body for a very short time but produces a large change in its momentum, is known as impulsive force.

Solution 51:
initial velocity of body = 0 ms^-1.
Final velocity of body = 100 ms^-1.
Mass of body = 20 kg.
Force applied = 100N.
We know that
F x t = m (v – u)
100 t = 20 (100 -0)
T = 2000/100 = 20 s.

Solution 52:
SI unit of retardation is ms^-2.

Solution 53:
Force applied is equal to the product of mass and acceleration produced in the body.
F = mass x acceleration.

Solution 54:
According to Newton’s second law of motion, when a force acts on a body, the rate of change in momentum of a body equals the product of mass of the body and acceleration produced in it due to that force, provided the mass remains constant.
Mass of body = 400 g = 0.4kg
Force applied on body = 0.02 N
Acceleration = force/mass = 0.02/0.4 = 0.05 ms^-2.

Solution 55:
Linear Momentum is defined as the physical quantity which is associated with bodies in linear motion. It is given by the product of the mass of the body and its velocity.
Mass of body = 1 kg
Acceleration produced = 10 ms^-2.
Force applied would be = 1 x 10 N = 10 N.
Mass of second body = 4 kg.
As same force has to be applied on second body so force = 10N.
Acceleration produced is = F/M =10/4 = 2.5 ms^-2.

Solution 56:
Mass of P is m₁= m.
Velocity of P is v₁ =2 v
Mass of Q is m₂ = 2m
Velocity of Q is v2 = v.

• inertia of P/inertia of Q = m₁/m₂ = 1/2.
  So ratio of inertia of two bodies is 1:2.
• Momentum of P/momentum of Q = m₁v₁/m₂v₂ = 1
  So ratio of momentum of two bodies is 1:1.
• As force required to stop them is equal to change in their momentum from moving to rest.
  So ratio would be same as the ratio of their momentum i.e 1: 1.

Solution 57:
According to newton second law
F = m x a
a= (v – u)/t.
F = m(v -u)/t
F = (mv – mu)/t
As F= m x a
ma = (mv – mu)/t
so rate of change of momentum = mass x acceleration.
This relation holds good when mass remains constant during motion.

Solution 58:

Solution 59:
According to newton third law, for every action there is always an equal and opposite reaction.
To demonstrate newton third law blow a balloon and hold its neck tightly facing downwards. When we release the balloon, the balloon will moves up instead of falling to the ground. As air is releasing from bottom of balloon and this air apply equal and opposite force to the balloon and this force helps balloon to move upwards.

Solution 60:
time for which force is applied = 0.1 s.
Mass of body = 2 kg
Initial velocity of body = 0 ms^-1
Final velocity of body = 2 ms^-1.
We know F x t = m (v – u)
F x 0.1 = 2 (2 – 0)
F = 4 /0.1 = 40 N.

Solution 61:
mass of ball = 500g = 0.5 kg.
Initial speed of the ball = 30 ms^-1
Final speed of ball = 0 ms^-1
Time taken by player to stop the ball = 0.03 s.
We know F x t = m (v – u)
F x 0.03 = 0.5 (0 – 30)
F = – 1.5 / 0.03 = – 500 N
(-) sign shows that player has to apply force in opposite direction of the motion of the ball.

Solution 62:
Time for which force is applied =0.1 s.
Mass of the body = 3.2 kg.
Initial speed of body = 0 ms^-1
After removal of forces body covers a distance of 3m in 1 second so final speed of body = 3/1 = 3ms^-1.
We know F x t = m (v – u)
F x 0.1 = 3.2 (3 -0)
F = 9.6/0.1 = 96 N.
So applied force is 96 N.

Solution 63:

PAGE NO : 131
Solution 64:
Time for which force is applied =3s.
Mass of the body = 2 kg.
Initial speed of body = 0 ms^-1
Force applied = 10 N.

• We know F x t = m (v – u)
  10 x 3 = 2 (v- 0)
  v = 15 ms^-1.
  Final velocity is 15 ms^-1.
• As m(v – u) is change in momentum and this is equal to the F x t so change in momentum is equal to the 30 kgms^-1.

Solution 65:

• We always prefer to land on sand instead of hard floor while taking a high jump because sand increases the time of contact.As F x t = m ( v – u ) and our change in momentum is constant so if time increases then force experienced would decrease.
• Again while catching a fast moving ball, we always pull our hands backwards to increase reaction time so force experienced would decrease.

Solution 66:
Height of cliff = 98 m.
Initial velocity of stone = 0 ms^-1.
Acceleration due to gravity = 9.8 ms^-2.

• We know H = ut + 1/2 gt².
  98 = 1/2 x 9.8 x t².
  t² = 98 x 2/9.8 = 20
  t= 4.47 sec.
• Final velocity when it strikes the ground
  v² – u² = 2 g H
  v² = 2 x 9.8 x 98
  v²= 1920
  v= 44.6 ms^-1.

Solution 67:
Initial speed of ball is = 9.8 ms^-1.
Acceleration due to gravity = -9.8 ms^-2.
Final speed at maximum height = 0 ms^-1.
We know v = u + at
0 = 9.8 – 9.8 t
T = 1 sec.
We know v² – u² =2as
At highest point final velocity is zero so
0 – 9.8 x 9.8 = 2 x (-9.8) S
S = 4.9 m.
for highest point initial velocity is zero
Acceleration due to gravity is = 9.8 ms^-2.
Final velocity at ground is v
V² – 0 = 2 x 9.8 x 4.9
V = 9.8 ms^-1.
Time taken to reach ground from highest point
V = u + at
9.8 = 0 + 9.8 t
T = 9.8/9.8 = 1 sec.
Total time = time of ascent + time of descent.
Total of flight = 1+ 1 = 2 seconds.

Solution 68:
Initial speed of ball = 10 ms^-1.
Acceleration due to gravity on ball = – 9.8 ms^-2
We know that from first equation of motion
v= u + gt.
After 1 sec
v= 10 – 9.8 x 1
v= 0.2 ms^-1
so velocity after 1 sec would be 0.2 ms^-1.
Velocity after 2 seconds
v= 10 – 9.8 x 2 = 10 – 19.6 = -9.6 ms^-1.
Here negative sign shows that velocity is in downward direction and magnitude is 9.6 ms^-1.

Solution 69:
Maximum Height attained by ball = 19.6 m
Let initial speed of ball = u ms^-1.
Acceleration applied on ball due to gravity = -9.8 ms^-2.
Final speed of ball at maximum height = 0 ms^-1.
We know that from second equation of motion
v² – u² = 2as
0 -u² = 2 x (-9.8) x 19.6
u² = 19.6 x 19.6
u= 19.6 ms^-1
so initial speed of ball to attain maximum height of 19.6 m should be 19.6ms^-1.

Solution 70:
Height of tower = 98 m
Acceleration due to gravity on stone = 9.8 ms^-2.
Initial speed of ball= 0 ms^-1.
Let initial speed of second stone is v ms^-1.
We know from second equation of motion
S = ut + 1/2 a x t².
98 = 0 + 1/2 x 9.8 x t².
t² = 20
t= 4.47 sec.
As second stone is thrown 1 sec later so time taken by second body to cover distance of 98 m is = 4.47 – 1 = 3.47sec.
So again put t= 3.47 sec and S = 98 m in second equation of motion we get
98 = v x 3.47 + 1/2 x 9.8 x 3.47 x 3.47.
98 = 3.47 x v + 59
3.47 x v = 98 – 59
v= 39/3.47 = 11.23 ms^-1.
Initial speed of second stone should be 11.23 ms^-1.

Solution 71:
Mass of object 1 m1 = 200 mg = 200 x 10^-6 kg = 2 x 10^-4 kg.
Mass of object 2 m2= 200 mg = 200 x 10^-6 kg = 2 x 10^-4 kg.
Distance between the two objects = 1 mm = 10^-3 m
We know law of gravitation is
F = G ( m1 x m2)/R²
F = (6.67 x 10^-11 x 2 x 10^-4 x 2 x 10^-4)/(10^-3 x 10^-3)
F = 6.67 x 2 x 2 x 10^-11-4-4+3+3
F = 26.68 x 10^-13 N
So these two objects would experience a force of 26.68 x 10^-13 N.

Solution 72:
Radius of earth = 6.38 x 103 km = 6.38 x 10⁶ m
G = 6.67 x 10^-11
Acceleration due to gravity = 9.8 ms^-2.
We know that
g= (G x M)/R².
9.8 = (6.67 x 10^-11 x M)/ ( 6.38 x 10⁶ x 6.38 x 10⁶)
9.8 x 6.38 x 6.38 x 10¹² = 6.67 x 10^-11 x M
398.9 x 10¹² = 6.67 x 10^-11 x M
M = 398.9 x 10¹²/6.67 x 10^-11
M = 59 x 10²³ kg
So mass of earth is 59 x 10²³ kg.

PhysicsChemistryBiologyMaths

Frank ICSE Solutions for Class 9 Biology – Interaction Between Biotic and Abiotic Factors in an Ecosystem

PAGE NO: 99

Solution 1:
Producers

Solution 2:
Consumers

Solution 3:
The climatic factors affecting ecosystem are sunlight, temperature, humidity, rainfall and wind.

Solution 4:
Low and high temperatures restrict the growth of plants and existence of animal species. Changes in temperature patterns will impact plant life which in turn will influence the animal life, since animals depend directly or indirectly on it for food. During extreme cold and hot conditions, animals either migrate to favourable places, some may hibernate or some may aestivate.

Solution 5:
Consumers which eat only plants are called consumers of the first order. Consumers that eat herbivores like deer, goats, grasshoppers, etc. are called consumers of the second order.

Solution 6:
Deserts have scanty water, either because there is little rainfall, or because the water evaporates very fast in deserts. Desert species are adapted to less amounts of water and they are capable of surviving for long periods of time in the scarcity of water. The growth of plants and animals and their vital functions are dependent on water intake. Hence water is a vital limiting factor in deserts due to the scant availability of this important resource.

Solution 7:

Solution 8:

Solution 9:
Vital atmospheric gases are oxygen, carbon dioxide and nitrogen.
Oxygen availability seldom becomes a limiting factor for land animals unless they live in soil or invade high altitudes. Plants release oxygen into the air which is used by animals for respiration. During respiration, animals release carbon dioxide which is required by plants for photosynthesis. Nitrogen is an essential gas which is vital for the growth and sustenance of organisms.

Solution 10:
In a natural ecosystem, green plants capture solar energy and convert it into chemical forms. The energy is then passed onto herbivores when they feed on green plants. From herbivores, the energy moves into carnivores that eat them. Some animals like lion and vultures are not eaten by other organisms. All the organisms ultimately pass on energy to the decomposers. Energy thus flows continuously through the ecosystem from plant to animals and from prey to predator.

Solution 11:
Energy passes through the ecosystem in a one-way path. Energy goes through each trophic level, one at a time. As it goes from one level to another, it is lost due to metabolism and in the form of heat. For example – The energy ingested by producers is used by the producers for carrying out various life activities and some amount of energy is lost as heat, so that the entire energy does not pass completely to the consumers. The energy lost as heat cannot be used anymore.

Solution 12:
The transfer of energy from autotrophs through a series of organisms that consume and are consumed is known as a food chain.

Solution 13:
The types of food chain are:

1. Grazing food chain
2. Detritus food chain
3. Auxiliary food chain
   (Write any two)

Solution 14:
Individual food chains interconnected in a complex way is called food web.

Solution 15:
An energy pyramid is a graphical representation of the flow of energy from the producers through the various consumers. It shows the amount of energy available and the loss of useful energy at each step of the food chain in an ecosystem.

Solution 16:
As the energy gets transferred from lower trophic level to the higher one, there is a loss of large amount of energy due to metabolism and as heat. As a result very little energy (i.e. 10%) gets transferred to the next level. So the trophic level at the base has maximum energy and that at the top has the least amount of energy. Hence energy pyramid is broader at the base and narrower at the top.

Solution 17:
(i)(a) unidirectional
(ii)(d) producers and consumers
(iii)(d) all the above
(iv)(a) photosynthesis
(v)(b) herbivores
(vi)(b) bacteria, fungi, etc.
(vii)(b) Communities and their physical environment
(viii)(d) solar energy
(ix)(d) biotic and abiotic
(x)(d) high temperature and high rain
BiologyChemistryPhysicsMaths