Work and Energy Q & A
Q.1. Fill in each blank with the appropriate term from the brackets.
(a) A bucketful of water is to be drawn from a well work will be done when a force is applied to do this, because there will be a displacement of water.
(displacement, work, force)
(b) If a ball is dropped on the sloping roof of a house, it acquires motion and falls on the ground. That is transformation of kinetic energy into potential energy takes place.
(kinetic, potential, motion)
(c) You might have seen some beautiful fireworks during Diwali. It is an example of transformation of chemical energy into light energy.
(light, atom, chemical, solar)
(d) The solar cooker is an application of the heat energy of the sun, while solar cells, solar lamps are applications of the light energy of the sun.
(light, chemical, heat)
(e) One labourer carried four pans of road metal through a distance of 100 metres. If he carries two pans of road metal through a 200 metre distance equal work will be done.
(equal, more, less)
(f) The capacity that an object has for doing work is called enery .
(energy, displacement, force)
Q.2. Match the pairs.
Column ‘A’ | Answers |
1. Rolling object | c. Kinetic energy |
2. Food | e. Chemical energy |
3. Stretched bow | d. Potential energy |
4. Sunlight | a. Heat energy |
5. Uranium | b. Atomic energy |
Q.3. Can you tell?
(a) When can we say that displacement has taken place?
Ans: When an object changes its position then we can say that displacement has taken place.
(b) What are the various forms of energy?
Ans: mechanical energy, heat energy, light energy, sound energy, chemical energy and electrical energy are the various forms of energy.
(c) Describe the natural chain of transformation of energy.
Ans: The natural chain of transformation of energy:
- In the course of water cycle, water evaporates due to the heat of the sun.
- This water vapour forms clouds that give rain.
- Rainwater flows into rivers and is stored in reservoirs or dams.
- This stored water at a height has potential energy.
- As the water falls down, this is transformed into kinetic energy.
- When the water falls on the turbine, its kinetic energy is transferred to turbine.
- The turbine rotates producing electrical energy.
(d) What should be taken into account for measuring work?
Ans: Force and displacement should be taken into account for measuring work.
(e) Why should we save energy?
Ans: We should save energy Due to increasing population and increasing use of energy resources in a large scale, there is a danger that limited reserves of coal, petrol, etc. will get exhausted.
(f) What is ‘green energy’?
Ans: The energy which doesn’t produce smoke and carbon gases such as carbon dioxide or carbon monoxide is called ‘green energy.
(g) What are the non-conventional energy resources?
Ans: The resources that have not been used traditionally, are inexhaustible and continuous and can be used in various forms again and again are called non-conventional energy resources.
e.g.: solar energy, wind energy, tidal energy, hydel power.
(h) Which forms of energy from the sun are used in solar energy devices?
Ans: Forms of energy from the sun that are used in solar energy devices:
- Heat energy from the sun is used in solar cookers, solar water heaters, solar driers.
- Light energy from the sun is used in solar cells and solar panels.
- Solar electric plants have the capacity to produce electricity on
large scale.
(i) Why should we maximize the use of non- conventional energy resources?
Ans: we maximize the use of non- conventional energy resources due to increasing population there is increasing use of conventional resources like petrol, coal, etc. Their reserves are limited and they may get exhausted that’s why it will be better to use non- conventional energy resources to save conventional resources for future.
Q.4. Who is the odd-one-out?
(1) Diesel, crude oil, natural gas, wind.
Ans: Wind.
(2) A running car, hauling a log, a book kept on a table, picking up the school bag.
Ans: A book kept on table.
(3) Sunlight, wind, wave, petrol.
Ans: Petrol.
(4) Leaving the fan on in a vacant room, leaving the TV on while working, using A.C during winter, putting off the light when going out.
Ans: Putting off the light when going out.
Q.5. Find out the types of energy from the following puzzle.
Ans: Potential, kinetic, solar, wind, sound, light, heat.