A 204g ball falls vertically downward, hitting the floor with a speed of 2.57 m/s and rebounding upward with a speed of 2.10 m/s. Calculate the magnitude of the change in the ball's momentum. Answer: 9.53E-01 kg*m/s Calculate the change in the magnitude of the ball's momentum. i really dont know how to go about the the second question. Any help? or tips?