12. Force, Work and Energy
A. Fill in the blanks.
1. A pulley is used to ________________, lower or ________________ a load.
2. ________________ is done when force applied on an object moves it.
3. ________________ is the force with which the earth pulls objects towards itself.
4. Muscular force is the force exerted by our ________________.
5. ________________ is a grooved wheel with a rope or a cable around it.
B.Answer the following questions.
1. What is force? What changes can force bring in an object?
2. What are the different types of forces?
3. Define work.
4. How does machine help us?
5. What are the different kinds of simple machines?
6. What is energy? Name the various forms of energy.
7. What is solar energy? How is it useful to us?
8. Define atomic energy.
9. What is a wedge?
10. How can we generate electricity?
11. What is muscular force?
12. Name a part of the human body which is an example of lever.
13. Name two devices in which electricity from solar energy is used.
C. Match the following.
Column A Column B
1. Screwdriver (a) Pulley
2. Can opener (b) Wedge
3. Lift (c) Wheel and axle
4. Axe (d) Lever
D. Tick the correct answer.
1. The energy released on joining or breaking of atoms is known as
(a) atomic energy (b) solar energy (c) magnetic energy
2. See-saw is an example of
(a) pulley (b) screw (c) lever
3. Which of these is not an effect of force?
(a) Change in colour (b) Change in size (c) Change in direction
4. The energy possessed by which of these is not used to turn turbines?
(a) Wind (b) The sun (c) Water
5. Which of these is used by plants to prepare their own food?
(a) Wind energy (b) Solar energy (c) Water energy
6. Falling of an apple from a tree is an example of
(a) gravity (b) work (c) friction
7. Knife is an example of
(a) screw (b) wedge (c) pulley (d) lever
8. The ability to do work is called
(a) energy (b) force (c) friction (d) gravity
9. Escalator is an example of
(a) inclined plane (b) lever (c) wedge (d) screw
10. Windmill works due to the energy generated from
(a) water (b) wind (c) sun (d) both (a) and (b)
E. Complete the following web charts.
F. Complete the crossword using the given clues.
Down: 1. The ability to do work (6)
2. The smallest particle of matter (4)
5. The main source of energy on earth (3)
Across: 3. The force by which the earth pulls everything towards itself (7)
4. Muscular force is the force exerted by our ___________. (7)
6. Its energy is used to turn windmills (4)
G. Answer in one word or few words.
1. Energy obtained from the sun.
H. Name the type of force responsible for the following.
1. A stone falling from a height
2. A man pushing a car
3. A ball thrown up in the air comes down
4. A girl slowing down her bicycle
5. A ball rolling on the ground comes to rest
I. Identify whether work is done or not in the following cases.
1. Rohan is pedaling his bicycle.
2. Aarushi is trying to push a tree.
3. Vishal has thrown a ball.
4. Sukriti is holding a flower vase.
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