A hockey ball of mass 200 g travelling at 10 ms–1 is struck, by a hockey stick so as to return it along its original path with a velocity at 5 ms–1. Calculate the change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick.
Mass of ball m = 200 g = 0.2 kg Initial speed of ball u = 10 m/s Final speed of ball v = – 5 m/s Initial momentum of the ball = mu = 0.2 kg x 10 m/s = 2 kg m/s Final momentum of the ball = mv = 0.2 kg x (_ 5 m/s) = – 1 kg m/s Hence, change in momentum = Difference in the momentum =2 – (–1) = 2 + 1 = 3kg m/s
