A heavy steel ball of mass greater than 1 kg moving with a speed of 2 m sec−1 collides head-on with a stationary ping-pong ball of mass less than 0.1 g. The collision between them was elastic. After the collision the ping-pong ball moves approximately with a speed of
We know that when heavier body strikes elastically with a lighter body at rest then after the collision, lighter body will move with double the velocity that of heavier body.i.e. the ping pong ball move with speed of 4 m/s