ICSE Class 7 Physics Important Questions Chapter 1 Physical Quantities and Measurement

Physics ICSE Class 7 Important Questions 1 Physical Quantities and Measurement

Additional Questions

A. Tick (✓) the following questions.

Question 1.
A physical quantity is that quantity which –
(a) occupies space
(b) can be measured
(c) has some mass
(d) all of these
Answer:
(b) can be measured

Question 2.
Length is the distance between basically –
(a) three number of points
(b) two points
(c) four number of points
(d) any number of points
Answer:
(b) two points

Question 3.
Length can be measured in metre having symbol (m) with the help of –
(a) a metre rod
(b) a measuring tape
(c) both (a) and (b)
(d) none of these
Answer:
(c) both (a) and (b)

Question 4.
Mass is the quantity of matter contained –
(a) in a body
(b) outside a body
(c) both (a) and (b)
(d) none of these
Answer:
(a) in a body

Question 5.
Mass can be measured in kilogram having symbol (kg) with the help of –
(a) beam balance
(b) spring balance
(c) electric balance
(d) both (a) and (c)
Answer:
(d) both (a) and (c)

Question 6.
Time is defined as that –
(a) duration in which something happens
(b) instant when something happens
(c) any of (a) and (b)
(d) none of these
Answer:
(c) any of (a) and (b)

Question 7.
Time is measured in second having symbol (s) with the help of –
(a) a watch
(b) a pendulum clock
(c) both (a) and (b)
(d) none of these
Answer:
(c) both (a) and (b)

Question 8.
Temperature is the degree of –
(a) hotness of a body
(b) coldness of a body
(c) any of (a) and (b)
(d) none of these
Answer:
(c) any of (a) and (b)

Question 9.
Temperature is measured with the help of thermometers in
(a) centigrade (°C)
(b) fahrenheit (°F)
(c) kelvin (K)
(d) all of these
Answer:
(d) all of these

Question 10.
Measurement is the comparison of an unknown quantity with a known quantity called.
(a) unit
(b) physical quantity
(c) symbol
(d) magnitude
Answer:
(a) unit

Question 11.
A body is said to be at rest with respect to surrounding if it
(a) does not change its position
(b) changes its position
(c) any of (a) and (b)
(d) none of these
Answer:
(a) does not change its position

Question 12.
A body is said to be in motion with respect to its surrounding if
(a) it does not change its position
(b) it changes its position
(c) any of (a) and (b)
(d) none of these
Answer:
(b) it changes its position

B. Answer the following questions.

Question 1.
Define volume.
Answer:
Volume is defined as the amount of three dimensional (3D) space covered by a substance say solid, liquid or gas.

Question 2.
Express volume of an object in a proper unit with proper symbol.
Answer:
Volume of a cube = V when length, breadth and height is in 1 metre.
V = 1 m x 1 m x 1 m
= 1 m³ , that is cubic metre

Question 3.
Measure volume of a liquid using a graduated cylinder and a graduated beaker.
Answer:
(a) Measurement of the volume of hair shampoo or handwash using graduated cylinder.
Material required : A graduated cylinder, table top, some hair shampoo or handwash.

Procedure :

1. Take a clean graduated cylinder and place it on the table top.
2. Pour the given liquid into the cylinder carefully without spilling.
3. Let the liquid settle down for some time.
4. Read the lower surface level of the liquid by maintaining the horizontal level of eye.
   
   Result: In the given figure, the reading is 50 ml which is the volume of the given liquid.

(b) Measurement of the volume of milk using graduated beaker.
Material required : A graduated beaker, table top, some milk.

Procedure :

1. Take a clean graduated beaker and place it on the tabletop.
2. Pour the given milk in the beaker carefully without spilling.
3. Let milk settle down for some time.
4. Read the lower surface level of the graduated beaker by keeping the horizontal level of eye.
   Result : In the given figure, the reading is 550 ml. It means that volume of milk is 550 ml.
   

Question 4.
Estimate the area of an object of irregular shape using a graph paper.
Answer:
Estimation of area of an irregular object using a graph paper. Material required : Sheet of graph paper (with big squares of area 1 cm² marked with thicker lines as shown in the ‘ figure), a big leaf, a pencil.

Procedure :

1. Place the leaf on the graph paper.
2. Mark the outline of the leaf with a sharp pencil carefully.
3. Count the number of complete big squares within the ; outline.
   
4. Count the number of squares covered more than half by the outline of the leaf.
5. Ignore the number of squares covered less than half by ) the outline of the leaf.

Result: Leaving the ignored squares, area of the leaf is equal to total number of counted squares. In the given figure the countable squares are ticked (✓). Therefore,
area of leaf = 7 squares As area of each square is 1 cm², therefore,
area of leaf = 7 cm²

Question 5.
Measure the volume of an irregular solid using a graduated cylinder/a graduated beaker.
Answer:
Measurement of volume of a given stone. Material required : A piece of stone, some water, a piece of thread and a graduated beaker or graduated cylinder.

Procedure :

1. Place the graduated beaker or cylinder on table.
2. Put some water in it and note the water level correctly. Let it be V₁
3. Dip the stone tied up with thread in the water completely.
4. Note the new water level rising due to dipping of the stone. Let it be V₂
   Result: Difference in the throw after levels is the volume of the stone, let it be V. Then, V = V₂ – V₁.
   

Question 6.
Define density and write its formula.
Answer:
The density of a substance is givsn by mass per unit volume of that substance.
density is given by Density

Question 7.
Express density in a proper unit and symbol.
Answer:
If mass of a substance is in kilogram, that is kg and volume
Kilogram
in cubic metre that is m³ then unit of density is
That is \(\frac{\mathrm{Kg}}{\mathrm{m}^{3}}\) or Kg m_-3
Density (D) =

Question 8.
Measure density of a regular/irregular solid.
Answer:
Measurement of density of a rectangular paper-weight made glass (regular solid).
Material required : A rectangular paper-weight made of glass, a scale, a common beam balance, standard measuring weights.

Procedure :
1. Using the common beam balance and measuring weights find the mass of the paper weight. Let it be M gram.
2. Using the scale measure length, breadth and thickness of the paper weight, let these be L, B and T cm respectively.

Result :
1. Calculate volume, that is, V = L x B x T cm³
2. Calculate Density, that is D = \(\frac{M}{L \times B \times T}\) g cm^-3
Measurement of density of the material of a pressure cooker weight (irregular solid).
Material required : Pressure cooker weight, a piece of thread, a common beam balance, a graduated cylinder, measuring weights.

Procedure :
1. Using the beam balance, measure the mass of the pressure cooker weight. Let it be M gram.
2. Fill some water in the clean graduated cylinder and note the level of the water. Let it be V₁
3. Tie thread to the pressure cooker weight and dip it fully in the water. Note the new level of water. Let it be V₂.

Result :
1. Volume of the ‘pressure cooker weight’ is given as
v = (V₂ – V₁) ml
But 1 ml = 1 cm3 for water
Therefore V = (V₂ – V₁) cm³

2. Density of pressure cooker weight is given by
D = \(\frac{\mathrm{M}}{\left(\mathrm{V}_{2}-\mathrm{V}_{1}\right)} \frac{\mathrm{g}}{\mathrm{cm}^{3}}\)

Question 9.
Express result of measurement in a proper unit with proper symbol.
Answer:
Measurement of density of irregular solid (spoon):
Mass of spoon =100 gm
Volume of water displaced = 12.5 ml
Density of spoon
Volume of water displaced = 12.5 ml
Since 1 ml = 1 cm³
Volume of spoon = 12.5 cm³

= 8 g cm³

Question 10.
Define speed and write its formula.
Answer:
Speed is defined as the distance covered by an object per unit time.

V = \(\frac {d}{t}\)

Question 11.
Express speed in proper units with proper symbol.
Answer:
Units of speed : If an object covers a distance of 1 metre in 1 second then unit of speed is = \(\frac {m}{s}\) or ms^-1 .

C. Tick (✓) the best choice :

Question 1.
3D stands for
(a) three days
(b) three dimensional
(c) three dates
(d) three districts
Answer:
(b) three dimensional

Question 2.
Measurement of volume of a rectangular box requires
(a) three values
(b) one value
(c) two values
(d) more than three values
Answer:
(a) three values

Question 3.
If area of a surface and thickness is known then volume can be thickness

Answer:
(c) area x thickness

Question 4.
Density of irregular bodies can be found with the help of –
(a) graduated cylinder
(b) graduated beaker
(c) (a) or (b)
(d) none of these
Answer:
(c) (a) or (b)

D. Fill in the blanks

Question 5.
Density of a substance is defined as ………….. per unit ………….. of the substance.
Answer:
Density of a substance is defined as mass per unit volume of the substance.

Question 6.
Volume of a substance is defined as …………. space ………….. occupied by that substance.
Answer:
Volume of a substance is defined as three dimensional space occupied by that substance.

E. Mark true or false against the given relations.

Question 7.
1 ms^-1 = 3.6 km h^-1
Answer:
True.

Question 8.
1 g cm^-3 = 1000 kg m^-3
Answer:
True.

F. Match the following :

Quantity Unit

(a) Speed	(i) kg
(b) volume	(ii) m
(c) mass	(iii) kg m
(d) density	(iv) ms-1
(e) length	(v) cm3

Answer:
Quantity Unit

(a) Speed	(iv) ms-1
(b) volume	(v) cm3
(c) mass	(i) kg
(d) density	(iii) kg m
(e) length	(ii) m

G. Solve simple numerical problems :

Question 10.
A box has a length of 10 cm, breadth of 6 cm and height of 4 cm. Find the volume of the box.
Answer:
Length of a box = 10 cm
Breadth of a box = 6 cm
Height of a box = 4 cm
Volume of the box = L x B x H = 10 cm x 6 cm x 4 cm = 240 cm^-3

Question 11.
A thick card board is cut into a square shape of side 10 cm. If thickness of the card board is 2 cm, find the volume of the cut-out.
Answer:
Side of square = 10 cm
Thickness of cardboard = 2 cm
Area of square cut out = Side x Side = 10 cm x 10 cm = 100 cm²
Volume of the cut out = Area x Thickness
= 100 cm2 x 2 cm = 200 cm³

Question 12.
Assess the area of an irregular object which is drawn on a graph paper having big squares of area 1 cm² each.

Answer:

Step 1 – Cross the squares covered less than half by the outline of the leaf.
Step 2 – Count the squares covered more than half by the outline of the leaf, here number of such squares is 5.
Step 3 – Area of leaf is 5 x 1 cm² = 5 cm².

Question 13.
Volume of a rectangular box is 300 cm3. If height of this box is 1 cm and breadth 15 cm then find the length of this box.
Answer:
Volume of rectangular box = 300 cm³
Height of the box = 1 cm
Breadth of the box = 15 cm
Let length of the box = L
Using, volume = L x B x H, we get
L = \(\frac {V}{B x H}\)
300 cm³ = L x 15 cm x 1 cm
L= \(\frac{300 \mathrm{~cm}^{3}}{15 \mathrm{~cm}^{2}}\)
L = 20 cm
Length of the box = 20 cm

Question 14.
Density of a liquid is 2 g cm^-3 . Volume of a sample of the liquid is 100 cm³. What is the mass of the sample?
Answer:
Density of a liquid is 2 g cm^-3
Volume of a sample of the liquid = 100 cm³
Let mass of the sample = M
Using, Density   , we get
Mass of the sample Density x Volume
\(\frac{2 \mathrm{~g}}{\mathrm{~cm}^{3}}\) x 100 cm³ = 200g

Question 15.
An irregular piece of an object is completely dipped in a measuring beaker. Initial level of water in the beaker before dipping the piece of object was 100 ml and final level of water after dipping the piece of object was 150 ml. If mass of the piece is object is 100 g, what is the density of the object?
Answer:
Initial level of water = V₁
V₁ = 100 ml
Final level of water = V₂
V₂= 150 ml
Volume of the piece of object
= Water displaced
= V₂ – V₁
= 150 ml – 100 ml
= 50 ml = 50 cm³ (because 1 ml = 1 cm³)
Mass of the object = 100 g
Density of the object =
\(\frac{100 \mathrm{~g}}{50 \mathrm{~cm}^{3}}\) = 2g cm^-3

Question 16.
A student cycles at a speed of 10 km h^-1. How much time she will take to reach the school at a distance of 4 km from her home assuming there is no obstacle on the way?

Answer:
Speed =10 km h^-1
Distance = 4 km
Time = ?

\(\frac{4 \mathrm{~km}}{10 \mathrm{~km} \mathrm{~h}^{-1}}\) = 0.4h

Question 17.
A labourer while going uphill covers a distance of 100 metre in 5 minutes and while coming downhill it covers same distance in 200 second. Is speed of labourer same in both cases? Which of the two speeds is more?
Answer:
Speed of the labourer downhill =

= 0.33 ms^-1

Speed of the labourer downhill  
\(\frac{100 \mathrm{~m}}{200 \mathrm{sec}}\)
= 0.5 ms^-1
No, the speed of labourer is different in both cases. His speed is more downhill.

ICSE Class 7 Physics Important Questions