# Homework Help: Principle of Work and Energy: Spring and Mass

1. Feb 15, 2012

### Peter P.

1. The problem statement, all variables and given/known data
When the 65-kg cylinder is released from rest, the spring is subjected to a tension of 75. Determine the speed of the cylinder after it has fallen 300. How far has it fallen when it momentarily stops?

Given Diagram:

2. Relevant equations

3. The attempt at a solution
I started with a displacement equation. When the mass has fallen 300 mm (or 0.3 m), the string should stretch 0.6 m. I think that i can use F = kx, where F = T. So then the spring is already stretched by 0.25 m. From the free body diagram of the cylinder, i know that there will be potential gravitational energy, and a tension force acting in the opposite direction. Heres my long shot, but can i make the tension be represented by the potential energy of the spring (Vs = 0.5ks2). Then i get a little lost in whether or not i can do that.

Thanks in advance for any help.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Feb 15, 2012

### ehild

Hi PeterP,

you are on the right track, go ahead.

ehild