Superposition of a crest and trough producesinterference

Avery hard rubber ball (m = 0.5 kg) is falling vertically at 4 m/s just before it bounces on the floor. the ball rebounds back at essentially the same speed. if the collision with the floor lasts 0.05 s, what is the average force exerted by the floor on the ball?

Which changes of state do the labels represent? a: b: c:

At what time would the magnitude of the velocity reach 36.00 km/hr