Question

A ball is dropped from a height of 10 m. If the energy of the ball reduces by 40% after striking the ground, how much high can the ball bounce back? (g = 10 m s^–2)

Answer 1

m g h = m ×10 ×10 = 100m J. 

Energy is reduced by 40% then the remaining energy is 60m J. 

Therefore, 60 m = m ×10 × h′ or h′ = 6 m