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**1. Homework Statement**

A tennis ball has a mass of 0.057 kg. A professional tennis player hits the ball hard enough to give it a speed of 50 m/s (about 112 miles per hour.) The ball moves toward the left, hits a wall and bounces straight back to the right with almost the same speed (50 m/s). As indicated in the diagram below, high-speed photography shows that the ball is crushed about 2 cm at the instant when its speed is momentarily zero, before rebounding. Assume that the large force the ball exerts on the wall is approximately constant during contact.

What is the average speed of the ball during the period from first contact with the wall to the moment the ball's speed is momentarily zero?

**2. Homework Equations**

DeltaP=Fnet*DeltaT

rFinal=rInitial+Vavg*DeltaT

**3. The Attempt at a Solution**

I'm not sure how to find this. I could find the avg velocity if I had the time it took to bring the ball to a stop, but that's the next question. Any help is greatly appreciated.