A particle executes simple harmonic motion with a frequency f . The frequency with which its kinetic energy oscillates is
f/2
f
2f
4f
Kinetic energy K=12mv2=12ma2ω2cos2ω t =14mω2a2(1+cos2ω t) hence kinetic energy varies periodically with double the frequency of S.H.M. i.e. 2ω .