Suppose that a 200g mass is oscillating at the end of a spring upon a horizontal surface that is frictionless. The spring can be compressed and stretched, and has a spring constant of 300 N/m. It was originally stretched a distance of 15 cm from its equilibrium (unstretched) position prior to release.
What are the values of the (a) potential energy, (b) kinetic energy, and (c) velocity of the mass when the mass is 10 cm from the equilibrium position.
KE = 1/2mv^2
PE = mgh
The Attempt at a Solution
I can't find the kinetic energy without finding the velocity first, but I don't know how to find the velocity in this instance. I don't know how to find the potential energy in this case either.