Spring problem - conservation of energy?

[ksherwood]

Homework Statement

A 15.0g ball is to be shot from a spring gun whose spring has a constant force of 600 N/m. The spring will be compressed 5.00 cm when in use. How fast will the ball be moving as it leaves? How high will it go if the gun is pointed vertically?

Homework Equations

I'm not quite sure which equations to use! This is what I need help with.

The Attempt at a Solution

 

[planck42]

You're on the right track by bringing up energy conservation.

 

[ksherwood]

do i find the potential energy of the system first, before trying to find these specific answers?

 

[planck42]

That's right