# Homework Help: Mass-spring system on an incline

1. Feb 24, 2010

### easchwen

1. The problem statement, all variables and given/known data
A spring is mounted at an angle of = 38 on a frictionless incline as illustrated in the figure below. The spring is compressed to 15 cm where it is allowed to propel a mass of 5.4 kg up the incline. If the spring constant is 565 N/m, how fast is the mass moving when leaves the spring? To what maximum distance from the starting point will the mass rise up the incline?

2. Relevant equations
PE=1/2kx^2 and KE=1/2mv^2

3. The attempt at a solution
I honestly don't know. I tried using PE=KE with the formulas above, and then tried adding in the cos(38) to the KE side, but I could not get the correct answer. Help?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Feb 24, 2010

### E=mc^84

Hi, im no expert ,but i think you solve for v like you did with PE=KE, and that equla that initial velocity of the mass leaving the spring. After you get that, you use the incline formula for acceleration: ma = -mgsin38, so, a = -gsin38. Then The object reaches a max height so V2 = 0: V2^2 = V1^2 + 2ax, and solve for x!

Hope this helps:)