# Homework Help: Physics Hwk Problem:Collisions

1. Oct 18, 2004

### shawonna23

A 0.165 kg projectile is fired with a velocity of +705 m/s at a 2.00 kg wooden block that rests on a frictionless table. The velocity of the block, immediately after the projectile passes through it, is +55.0 m/s. Find the velocity with which the projectile exits from the block.

I am having trouble solving this problem. I used this equation:
vf1=(0.165-2.00)/(0.165+2.00)*705, but the answer is wrong. Am I using the right equation?

2. Oct 18, 2004

### BlackMamba

LOL, we could quite possibly be in the same class. Again, yet another homework problem that I had.

I can tell you that no, that isn't the correct equation to be using. Look in your book under 7.4 : Collisions in Two Dimensions and you will get the correct equation to use from there.

3. Oct 19, 2004

### PeteTully

this question seems as if it is a conservation of momentum problem.
therefore,
initial momentum (before collison) must be equal to the
final momentum (after collison)

so just equate the two and you should get the correct answer.

hope this helps.