# Homework Help: Force of bat on ball

1. Oct 22, 2009

### futureteacher

1. The problem statement, all variables and given/known data
A 0.145 ball is pitched at 37 m/s and is hit on a horizontal line drive at 51.5 m/s. If the contact time between the ball and the bat is 3.5x10-3 seconds what is the avg force between the bat and the ball during contact.

2. Relevant equations
P=mv
$$\Sigma$$F=$$\Delta$$P/$$\Delta$$T

mfinal*vfinal-minitial*vinitial/$$\Delta$$Time

factor out m (mass)
m(vfinal-vinitial)/$$\Delta$$t

3. The attempt at a solution
0.145kg(51.5m/s-37.0m/s)/(3.5*10-3)

i get 600N but my webwork says that not right i have no idea what im doing wrong

2. Oct 22, 2009

### Andrew Mason

The change in velocity is 51.5 + 37.0 m/s. The ball is hit in the opposite direction to the pitch.

Don't forget that force and momentum are vector quantities. The definition of force is:

$$\vec F = \sum \vec F_i = \frac{d\vec p}{dt}$$

AM

Last edited: Oct 22, 2009