Basic Physics Tutorials

Work-Kinetic Energy principle

If net force works on an object, the object experiences acceleration (the object experiences displacement). When the object experiences acceleration, the speed of the object changes. In other words, the work done by the net force is related to the object’s initial and final speed.

The work done on an object by constant net force is:

W_net = ΣF s

Newton’s second law states that if there is a net force working on an object, the object experiences acceleration.

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Work done by force

1.1 Definition of Work

If you push a book on the surface of a table until the book is displaced, you are said to have done work on the book. If an object falls to the ground due to the pull of gravitational force, the gravitational force is said to have done work on the object. On the contrary, if you push an object with all your might to the point that you sweat profusely, but the object does not move at all, you are said to have done no work on the object. In everyday life, people might say that you have done hard work by pushing the object but in Physics, you did not do work on the object because there has been no displacement of the object.

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