# Momentum and Impulse

1. Mar 1, 2012

### nhmockus

A 0.145-kg baseball pitched at 35.0m/s is hit on a horizontal line drive straight back toward the pitcher at 57.0 m/s.
If the contact time between bat and ball is 2.50×10−3s , calculate the average force between the ball and bat during contact.

The equation has something to do with nonelastic collisions but it has no external forces so it should have something like m*(v(f)-v(i)/change in t

I tried to plug and chug but it wasn't correct. ((57-22)*.145)/(2.5*(10^-3) The answer I came out with was 1276

2. Mar 1, 2012

### genericusrnme

Where did the 22 come from?

3. Mar 1, 2012

### nhmockus

Haha that's what i found. Sorry, it should be 57-35 to = 22. I did it correctly in my calculations

4. Mar 1, 2012

### genericusrnme

Think about which direction the velocity is going in, are you sure the change in velocity is 57-35=22?

5. Mar 1, 2012

### nhmockus

Why wouldn't it be? Or are you saying that it could be negative?

6. Mar 1, 2012

### genericusrnme

If I am traveling east at 5m/s, then I turn around and start traveling west at 3m/s, what is the change in my velocity?