JCECE Engineering JCECE Engineering Solved Paper-2006

  • question_answer
    A particle executes simple harmonic motion with a frequency\[f\]. The frequency with which its kinetic energy oscillates is:

    A) \[f/2\]                                  

    B) \[f\]

    C)  \[2f\]                                   

    D)  \[4f\]

    Correct Answer: C

    Solution :

    For a particle executing \[SHM\] the displacement equation is given by                 \[y=a\sin \omega \,t=a\sin 2\pi ft\] kinetic energy \[KE=\frac{1}{2}m{{v}^{2}}=\frac{1}{2}m{{\left( \frac{dy}{dt} \right)}^{2}}\] where   \[\frac{dy}{dt}=2\pi \,\,fa\cos 2\pi ft\] \[\therefore \]  \[KE=\frac{1}{2}m\{{{(2\pi fa)}^{2}}{{\cos }^{2}}2\pi ft\}\]                 \[KE\propto (1+\cos 4\pi ft)\] \[\cos 4\pi ft\] changes periodically with frequency\[2f\].


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