# A train that is momentarily at rest, Newton's Laws

1. Oct 28, 2009

### cloudage

1. The problem statement, all variables and given/known data
A train is traveling up a 3.73 degrees incline at a speed of 3.25 m/s when the last car breaks free and begins to coast without friction.
a) How long does it take for the last car to come to rest momentarily?
b) How far did the last car travel before momentarily coming to rest?

2. Relevant equations

3. The attempt at a solution
I tried to draw the free body diagram, but since I have either mass or a force I don't know how to proceed. Momentarily at rest means that it's velocity is zero, but I don't know it's acceleration after the car has been released so I can't use the kinematics.

2. Oct 28, 2009

### PhanthomJay

After the car is released, you should be able to find its acceleration. What net force acts on the car when it is released?

3. Oct 28, 2009

### cloudage

I got it, thank you very much! It would just be gravity acting on it, so I can find the component by using sine. Thanks!!

4. Oct 28, 2009

### PhanthomJay

Yes, and welcome to PF!