ICSE Class 6 Physics Important Questions Chapter 6 Work and Energy

Physics ICSE Class 6 Important Questions Chapter 6 Work and Energy

Practice Questions

Question 1.
Define work in terms of physics.
Answer:
Work is said to be done when a force is applied on an object and the object gets displaced under the action of that force.

Question 2.
Give an example of work done when there is a change in a shape or size of an object due to the force aplied on it.
Answer:
Rolling a ball of wheat dough into chapatti and shaping toys with moulding clay.

Question 3.
Mention situations when no work is said to be done.
Answer:
There can be no work done if :

• There is no force applied.
• A force is applied but there is no displacement,
• A force is applied, the objet moves, but comes back to the starting point.
• A force is acting on the object, the object moves, but not because of the applied force (when force and displacement are at right angles to each other).

Question 4.
Define a joule.
Answer:
1 joule is defined the amount of work done if a force of 1 newton causes a displacement of 1 metre in the direction of tibe applied force. It is denoted as J.
1 J = 1 N x l m 1 J = 1 Nm

Question 5.
Define energy. What is its unit ?
Answer:
Energy can be defined as the ability to do work. SI unit is joule (J).

Question 6.
Explain how a stretched elastic band of a catapult possess elastic potential energy.
Answer:
When the elastic band of a catapult is stretched (work done), elastic potential energy gets stored in the band. When the band is released, it can make a stone move with a great speed (work done). The kinetic energy of the moving stone is obtained from this elastic potential energy stored in the band.

Question 7.
Name few forms of stored energy.
Answer:
1. Chemical energy – Energy stored in matter that can become available for work through chemical process is called chemical energy. Example : The energy of the food that we eat is stored as chemical energy in our body, fuels such as coal, petrol, etc. have chemical energy stored in them.
2. Magnetic energy – It is the energy stored in the magnets.
3. Nuclear energy – The energy released when nucleas of an atom splits or when two nuclei of different atoms combine is called nuclear energy.

Question 8.
What is a photon ?
Answer:
Light contains very minute packets of energy called photons. When a source of light gives out more photons, more energy is released and the light is bright. When the amount of photons released from a light source is less, you see a dim light.

Question 9.
Give few examples of transformation of energy.
Answer:

Question 10.
What is the law of conservation of energy ?
Answer:
According to the law of conservation of energy, energy can neither be created nor be destroyed but it can be converted from one form to another.

Question 11.
Name some sources of energy.
Answer:
Solar energy, energy from biomass, wind energy, eriergy from flowing water, energy from fossil fuels, energy from sea waves.

Question 12.
Write short note on fossil fuels.
Answer:
Fossil fuels are coal, natural gas and petroleum which give heat and light energy on burning. Fossil fuels are formed from remains of plants and animals buried deep in the earth’s crust by a slow process which takes millions of years. Coal was formed from the remains of forests that got buried under layers of rocks whereas petroleum’ and natural gas were fromed from the remains of organisms buried under the sea.

Question 13.
Give an example of energy chain.
Answer:

Question 14.
Mention some energy-saving tips.
Answer:

• Use car pool and public transport instead of personal vehicle to save petrol and diesel.
• Switch off fans, lights and other electrical gadgets when not in use.
• Use solar cookers and solar heaters.

Question 15.
Give one use each of :

1. Magnetic energy
2. Nuclear energy
3. Chemical energy
4. Energy from biomass
5. Energy from flowing water

Answer:

1. Used to separate iron from scrap with the help of an electromagnetic crane.
2. Used to generate electricity and in treatment of cancer.
3. Diy cell and car battery have chemical energy stored in them which is converted into electrical energy when put to work.
4. Chemical energy of biomass is used as fuel to obtain energy. Biomass is converted into biogas which is a cheap and environment-friendly fuel used in villages for cooking etc.
5. The kinetic energy of falling water is used to rotate the blades of a turbine that produces electricity with the help of a generator.

Question 16.
Fill in the blanks.
(i) ………….. is the shortest distance travelled between two points.
Answer:
Displacement is the shortest distance travelled between two points.
(ii) Greater the magnitude of force applied or displacement, ………… is the work done.
Answer:
Greater the magnitude of force applied or displacement, more is the work done.

(iii) 1 KJ = ………….. J
Answer:
1 KJ = 1000 J

(iv) ………….. gave the theory of conservation of energy.
Answer:
James Prescott Joule gave the theory of conservation of energy.

(v) The SI unit to measure work and energy is the …………. i.e., joule (J).
Answer:
The SI unit to measure work and energy is the same, i.e., joule (J).

(vi) ………… is the form of energy that enables us to see objects around us.
Answer:
Light is the form of energy that enables us to see objects around us.

(vii) …………. energy is measured by temperature.
Answer:
Heat energy is measured by temperature.

(viii) Heat energy flows from a body at a temperature to a body at ………… temperature.
Answer:
Heat energy flows from a body at a higher temperature to a body at lower temperature.

(ix) Energy derived from the heat in the interior of the earth is called ………… energy.
Answer:
Energy derived from the heat in the interior of the earth is called geothermal energy.

(x) A drum produces ………….. energy on striking.
Answer:
A drum produces sound energy on striking.

(xi) Light energy of the sun is changed to chemical energy of food during the process of ………….. in plants.
Answer:
Light energy of the sun is changed to chemical energy of food during the process of photosynthesis in plants.

(xii) …………… is the ultimate source of energy on earth.
Answer:
Sun is the ultimate source of energy on earth.

(xiii) The organic matter present in plants and animals is known as …………..
Answer:
The organic matter present in plants and animals is known as biomass.

(xiv) The energy generated by flowing water is called …………..
Answer:
The energy generated by flow’ing water is called hydro electricity.

(xv) On burning fuels, ………….. energy stored in them is converted to heat and light energy.
Answer:
On burning fuels, chemical energy stored in them is converted to heat and light energy.

(xvi) ………….. are non-renewable sources of energy as these cannot be used repeatedly and deplete on use.
Answer:
Fossil fuels are non-renewable sources of energy as these cannot be used repeatedly and deplete on use.

(xvii) A body with more energy can do ………… work than a body with less energy.
Answer:
A body with more energy can do more work than a body with less energy.

(xviii) ………….. is defined as the product of force applied and displacement in the direction of the applied force
Answer:
Work is defined as the product of force applied and displacement in the direction of the applied force

(xix) ………….. energy is used for cooking and keeping ourselves warm.
Answer:
Heat energy is used for cooking and keeping ourselves warm.

(xx) The energy of the sun reaches us through a series of conversations called as ……………
Answer:
The energy of the sun reaches us through a series of conversations called as energy chain.

ICSE Class 6 Physics Important Questions