Energy possessed by an object due to its motion is termed as its Kinetic Energy.
It follows that if there is no motion, or the object is stationary, its kinetic energy is zero.
From Law of conservation of Energy we also know that energy can not be created. It however, can be changed from one form to another.
It is assumed mass is constant.
We know that work done in accelerating an object of mass
Using Newton's Second law of Motion
the integral becomes
Writing acceleration in terms of velocity
Rearranging we get
We know that
Assuming that the object was at rest at time
As work done is zero when