A simple harmonic oscillator has a total energy of E.?

Question

a) Determine the potential energy when the displacement is 4/5 the amplitude

b) Determine the kinetic energy when the displacement is 4/5 the amplitude

I posted this once and the answer i got was hard to follow. I figured out one part but I still need a little help understanding it. thanks

Answer 1

You don't need to know ω, k or m to answer this.

PE is proportional to displacement^2. (PE = kx^2/2.)

A. When x = 4A/5, PE = (4/5)^2*E = 16/25*E

B. E = KE + PE. KE = E - PE = 9/25*E

EDIT: Since the answerer who provided a solution involving  ÃÂ‰, k and m withdrew his/her answer, the first sentence above is now a straw-man statement, FYI only.