Question

A ball of mass 200 g falls from a height of 5 metres. What is the kinetic energy when it just reaches the ground? (g = 9.8 $m/s^2$).

Answer 1

height = 5 m
mass = 200 g (0.2 kg)
g = 9.8 m/$s^2$
∴ Potential energy = mgh = 0.2 $\times$ 5 $\times$ 9.8 = 9.8 J
∵ P.E. at the highest point = K.E. at the lowest point (when it is just about to hit the ground)
∴ K.E. energy will be = 9.8 J