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 of 5 ms^-1.

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 of 5 ms^-1. Calculate the change of momentum which occurred in the motion of the hockey ball by the force applied by the hockey stick: