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Oscillations

Question
CBSEENPH11026137

A pendulum is undergoing SHM with frequency f What is the frequency of its kinetic energy ?

  • f2

  • 2 f

  • 3 f

  • 4 f

Solution

B.

2 f

Suppose  A particle in s.H.M follows the equation

X = A sin ωtdXdt = V =A ω cosωtSo, kinetic energy = 12  mv2                                =12m A2 ω2  cos2ωtNow if a particlewould have been moving following such equation i.eY =12m A2 ω2 cos2ωtY = 14 m A2 ω2 2 cos2ωtY= 14 m A2 ω2 sin2ωt +1Y -  14m A2 ω2   =  14m A2 ω2 sin 2ωty= 14m A2 ω2 sin 2ωt                                             since y=Y -14m A2ω2= constant14m A2ω2 - Amplitudesin 2ω t - has been doubled so frequency is doubled as well