Work

Force changes the motion (momentum). But during the change in motion, the body on which the force is applied also moves through some distance. This leads to some more basic concepts of science - work, power and energy.

Work is said to be done when force is applied on a body and the body moves through some distance in the direction of force. It implies that:

1. If a force is applied on a body and the body does not move then no work is done at all.

Example: When you try to push a wall you do not do any work as distance moved by the wall is zero.

2. If no force is applied on a body and the body is either at rest or moving with a constant velocity then again no work is done.

Example: A car moving with a constant velocity on a level road does not do any net work. Because the fuel it consumes is used in doing work against fraction, so that, its velocity may be maintained.

3. If the force and displacement are perpendicular to each other, the work done by the force is zero.