We know that If a ball of mass 1 kg is kept at a height 10 m possesses potential energy 'mgh' i.e. (1×10×10)=100 J.
(Take earth surface as the reference, where m = mass of the object, g = acceleration due to gravity, h = height of the object from the earth's surface)
What will be the kinetic energy of the ball when the ball is allowed to freely fall from a height 10m from the surface of the earth and hits the ground?
(Take g=10ms2 and neglect air drag)
100 J
Initially, the ball has potential energy which is later converted to kinetic energy.
Potential energy = 1×10×10=100 J (at h = 10m)
When the ball reaches the bottom, i.e., h = 0, potential energy will become 1×10×0=0 J.
So in absence of air drag, all potential energy will be converted to kinetic energy.
Therefore, kinetic energy when the ball hits the ground will be 100 J.