Question

A ball is dropped from a height of 10m. If the energy of the ball reduces by 40% after striking the ground, how much high can the ball bounce back ?

(g 5 10ms22

Answer 1

When the ball is dropped from a certain height, it will have some stored gravitational energy. This energy can be shown by 

 GPE = m x g x h

 The potential energy of gravity is directly affected by the height. When the ball is dropped from a 10m height, it loses 40% energy thus affecting the same percentage of height when it bounces back.

Now 40% of the energy lost means 40% of the height also lost on bouncing back. Given height is 10m and when you lose 40% of 10m, left will be 60% of 10m. 

 The height of the bounce back is hence 60% of 10m which 6m.