A 400-gram football is moving in the positive x-direction with a speed of 7 m/s. Cristiano Ronaldo hits the ball with his head and sends it in the opposite direction with a speed of 15.5 m/s. Find the change in the ball's linear momentum, consider only the x-component of the momentum. The change in the ball's momentum, Ap = Units kg*m/s If the time of contact between the ball and Cristiano's head is 33 msec, find the average force exerted on the ball. The force on the ball, F = = Units N What is the force exerted by the ball on Ronaldo's head? The force on the head, F = Units N