# Homework Help: Average Force of Impulse?

1. Oct 31, 2009

### Psych Berry

I can't seem to master this equation, because I think I'm doing things right and I'm not.

1. The problem statement, all variables and given/known data
When a 410 baseball gram is hit, its velocity changes from +28.87 m/s to -22.34 m/s. The baseball is in contact with the bat for 56.10 milliseconds. You may assume that the balls outward velocity is antiparallel to its incoming velocity.

What is the magnitude of the average force on the ball?

2. Relevant equations
FΔt = mΔv

3. The attempt at a solution
(0.410 kg)(-22.34 m/s - 28.87 m/s)/(0.0561 s) = F
374.3 N = F
But this isn't correct.

I messed up Δv before, did I do it again?

2. Oct 31, 2009

### Staff: Mentor

Looks OK to me. Why do you say it's wrong?

3. Oct 31, 2009

### Psych Berry

It's an online pre-assignment, said my answer was incorrect. I tried playing around with sig figs and signs (in case the question forgot it's supposed to be magnitude), but I've tried 5 times and haven't been able to get it correct.

4. Oct 31, 2009

### Staff: Mentor

Those online systems can be flaky. But there's nothing wrong with your understanding of that impulse-momentum equation.

5. Oct 31, 2009

### Psych Berry

That's definitely true, thanks! I for sure trust your physics judgment over the program's.