What is work done by gravity?

 

When a body is dropped from some height, it falls vertically downwards under the action of gravity. Here the body is displaced in the direction of the gravitational force, and so work is done by gravity. Consider now a man lifting a load.

Here work is done by gravity. consider now a man lifting a load. Here work is done by the force applied by the man, but against gravity, since the displacement and the gravitational force are opposite. In the case of a horse pulling carriage, work is done by the horse but against the frictional force of the road.

The work done is zero when theta = 90 degree , i.e . when the point of application is displaced perpendicular to the force. For example, the gravity does not do any work on a car moving horizontally, the displacement being horizontal and the force vertical. forces not doing any work are termed no- work forces.