Question

A hockey ball of mass 200 g traveling 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 the change of momentum that occurred in the motion of the hockey ball by the force applied by the hockey stick.

Answer 1

Mass of hockey ball m= 200 g = 0.2 kg Initial velocity, u= 10ms -1 Final velocity, v= –5ms-1 (Since the final velocity of the ball is in the direction opposite to the direction of the initial velocity.)
Change in momentum of the ball = Final momentum – Initial momentum
= mv–mu
= m(v–u)
= 0.2 (–5–10)
= 0.2 ×–15
= –3 kg ms–1