# Tennis ball drop problem

#### barobinson630

1. The problem statement, all variables and given/known data

You drop a tennis ball from 4.36 m. It rebounds to height of 2.45m. If the ball is in contact with the floor for 10.0 ms, what is its average acceleration during that contact?

2. Relevant equations
we know initial height to be 4.36 m
acceleration due to gravity to be 9.8 m/s^2
contact for 10.1 ms
rebound height of 2.45 m

3. The attempt at a solution
Im completely lost, don't know where to start

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#### kuruman

Homework Helper
Gold Member
Start by finding the velocity of the ball just before it hits the floor and just after it bounces off the floor.

#### cepheid

Staff Emeritus
Gold Member
Welcome to PF barobinson630!

Given the initial height, you can figure out the velocity of the ball upon impact. From that, you know its momentum just before hitting the ground.

Given the maximum height it reaches on the rebound, you can easily figure out its velocity at the instant of leaving contact with the ground. So you know its momentum just after the collision.

So, you know the change in momentum of the ball that occurred as a result of the contact force from the ground. If you know the change in momentum of the ball, then you know the impulse that was supplied to the ball (since these are the same thing). You also know the time interval over which this impulse was applied...

#### barobinson630

nevermind...i figured it out

#### barobinson630

thank you though!

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