(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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 44 m/s (about 99 miles per hour.) The ball moves toward the left, hits a wall and bounces straight back to the right with almost the same speed (44 m/s). As indicated in the diagram below, high-speed photography shows that the ball is crushed about d = 2.1 cm at the instant when its speed is momentarily zero, before rebounding.

What is the magnitude of the average force exerted by the wall on the ball during contact?

2. Relevant equations

pf=pi+Fnet([tex]\Delta[/tex]T

3. The attempt at a solution

For this problem, we also had to solve for the average speed from contact to 0, [tex]\Delta[/tex]T, and mag. of Fgrav.

vavg= 22 m/s in x direction

[tex]\Delta[/tex]T= 9.5455e-4 sec

mg=.5586 N

I got those right. Now for my attempt at the force.

I know that

pf=pi + Fnet [tex]\Delta[/tex]T.

and

pavg= m(vavg)

= (.057)(22)

= 1.254

I assumed that Favg=pavg/[tex]\Delta[/tex]T

and got

Favg= (1.254)/(9.5455e-4)

= 1313.708

That's not right.

Help would be greatly appreciated!

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# Homework Help: Average force of a tennis ball

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