Kinetic energy and impulse in a ball...?

Question

A ball having a mass of 150 g strikes a wall with a speed of 5.2 m/s and rebounds with only 50% of its initial kinetic energy. (a) What is the speed of the ball immediately after rebounding? (b) What is the magnitude of the impulse on the wall from the ball? (c) If the ball was in contact with the wall for 7.6 ms, what is the magnitude of the average force on the ball from the wall during this time interval? Can you explain how you get your answers?

Answer 1

a) K.E. = 0.5 m v^2
Half the K.E. = v/sqrt(2)
v = 3.677 m/s

b) m * delta v = 1.33 kg m / s

c) answer from b / 7.6ms = 175.2 N