# Momentum question REALLY NEED HELP

1. Sep 24, 2007

### envoystud

momentum question...REALLY NEED HELP!!

1. The problem statement, all variables and given/known data
A .22 rifle bullet, traveling at 350 m/s, strikes a block of soft wood, which it penetrates to a depth of 0.130m . The block of wood is clamped in place and doesn't move. The mass of the bullet is 1.80g. Assume a constant retarding force.

??-How much time is required for the bullet to stop? (in seconds)

??-What force, in newtons, does the wood exert on the bullet?

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Sep 25, 2007

### Dick

Kinematics, think x(t)=x0+v0*t+(1/2)*a*t^2. What acceleration is required to stop the bullet? Once you have a, what force is needed to stop the bullet? Now think of Newton's third law.