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Let’s
Revise

 Any kind of force is really just a push or a pull.
 A force can cause an object to accelerate, slow down, remain in place, or change

shape.
 Friction is a force that tries to stop a moving object.
 Machines are devices which make the work easier and reduce the effort.
 Energy is the ability to do work.
 Kinetic energy is energy due to the motion of object.

Points to Remember

Force : A push or pull
Work : It means to move an object from its place by applying the force
Energy : The ability to do work

E XE R C I S E

A. Tick () the correct answer.
1. Any kind of force/work is just a push or pull.
2. Gravity/Friction is a force that tries to stop a moving object.
3. Rough/smooth surface has less friction.
4. We need force/energy to do our work.
5. An axe is a wedge/screw.

B. Write ‘T’ for true and ‘F’ for false.
1. If we push on something or pull on it, then we are
applying a force to it.
2. The earth pulls anything towards itself by frictional force.
3. Seesaw is a lever.
4. The sun is the main source of heat on the earth.
5. Potential energy is due to the motion of an object.

C. Give one example of the following types of machines.
1. Lever
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