Question

Derive the expression for kinetic energy.

Answer 1

Let a body of mass m be moving with a uniform velocity u. Let an external force be applied on it so that it displaces a distance s and its velocity becomes v.

We have velocity-position relation as:

v² = u² + 2as

Where, a = acceleration of the body during the change of velocity

Hence, work done on the body by the force will be given by,

W = F × s

F = ma

If the body was initially at rest i.e., u = 0, then

This is required expression. Its SI unit is Joule (J).