# Conservation of energy between the mass and the spring

1. Jun 22, 2007

### Momentum09

1. The problem statement, all variables and given/known data

A 1500g mass starts from rest and slides a distance L down a frictionless 21 degrees incline, where it contacts an unstressed 60cm long spring of negligible mass. The mass slides an additional 10cm as it is brought momentarily to rest by compressing the spring of force constant 15N/cm. Find the initial separation L between the mass and the spring.

2. Relevant equations

1/2 kx^2 = mgh, where h = sin21 (L+0.6)

3. The attempt at a solution

I first converted all the dimensions: 1500g to 1.5kg, 60 and 10cm to 0.6m and .1m respectively, and 15N/cm to 1500N/m. I then plug in my answer to solve for h. After that, I divide h by sin21 and finally subtract 0.6 from it. I thought I did the question correctly, but I keep getting it wrong. Can someone please point out my mistake?

Thank you so much!

2. Jun 22, 2007

### Momentum09

nvm, I got it!