# Homework Help: What is the magnitudue of the force acted on the ball

1. Oct 23, 2008

### knelson

A 536 g ball stricks a wall at 15.8 m/s and rebounds at 13.1 m/s. The ball is in contact with the wall for 0.038 s.

What is the magnitudue of the force acted on the ball during the collision?

2. Oct 23, 2008

### tiny-tim

Hi knelson!

Show us what you've tried, and where you're stuck, and then we'll know how to help.

3. Oct 23, 2008

### knelson

Re: Collision

Well we (me and the girl who are studying together) we have the answer... and we can get the answer but we don't understand why.

We used F=ma to find the force using the initial velocity and did the same thing using the second velocity and added them together. We come up with the correct answer but we don't understand why.

4. Oct 23, 2008

### knelson

Re: Collision

It's 407.642

5. Oct 23, 2008

### tiny-tim

Hi knelson and friend!

Newton's second law :

force = rate of change of momentum​

so if you multiply that by time, you get:

force x time = change of momentum