a spring with spring constant k= 100N/m is at its equilibrium length

Question

a) how much elastic potential energy is stored in the spring?
b) the same spring is stretched so that it is 6cm longer than it was. How much elastic potential energy is stored in the spring now?
c) a different spring with spring constant four times larger than in part (a) is compressed so that it is 2cm shorter than its equilibrium length. How much elastic potential energy is stored in this spring?

Answer 1

I am not certain of what you are stuck on. At equilibrium, there is no PE stored in the spring. When using F=kx, and KE=1/2 k x^2, be certain x is in meters.