A hockey ball of mass 200 g travelling at 10 m s–1 is struck by a hockey stick so as to return it along its original path with a velocity at 5 m s–1. Calculate the magnitude of change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick.

Mass of the hockey ball, m = 200 g = 0.2 kg

Hockey ball travels with velocity, v1 = 10 m/s

The change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick.

Initial momentum of the ball = mu = 200g × 10 ms-1 = 2000 g.m.s-1

Final momentum of the ball = mv = 200g  × –5 ms-1 = –1000 g.m.s-1

Therefore, the change in momentum (mv – mu) = –1000 g.m.s-1 – 2000 g.m.s-1 = –3000 g.m.s-1

This implies that the momentum of the ball reduces by 1000 g.m.s-1 after being struck by the hockey stick.