Question

A ball of mass 200 gram falls from a height of 5 meters. What is its kinetic energy when it just reaches the ground ? ( acceleration due to gravity = 9.8 m / s²)

Answer 1

Given, height, h = 5 m; mass of the ball, m = 200 g = 0.2 kg

When the ball is falling, its PE is converted into KE, so that the total energy is constant.

When the ball just reaches the ground, total PE is converted into KE.

So, KE = PE

KE = mgh

KE = 0.2 x 10 x 5

KE = 10 J