J & K CET Medical J & K - CET Medical Solved Paper-2002

  • question_answer
    The kinetic energy and potential energy of a re executing simple harmonic motion will be equal, when displacement (amplitude = a) is:

    A) \[a\sqrt{2}\]                                      

    B) \[\frac{a}{2}\]

    C) \[\frac{a\sqrt{2}}{3}\]                                   

    D) \[\frac{a}{\sqrt{2}}\]

    Correct Answer: D

    Solution :

                     When a body executes SHM it has both potential energy\[(U)\]and kinetic energy\[(K)\]given by \[U=\frac{1}{2}m{{\omega }^{2}}{{y}^{2}}\] where m is mass,\[\omega \]the angular speed and y the displacement. Also,      \[K=\frac{1}{2}m{{\omega }^{2}}({{a}^{2}}-{{y}^{2}})\] where a is amplitude. Given,         \[K=U\] \[\therefore \]  \[\frac{1}{2}m{{\omega }^{2}}({{a}^{2}}-{{y}^{2}})=\frac{1}{2}m{{\omega }^{2}}{{y}^{2}}\] \[\Rightarrow \]               \[{{a}^{2}}=2{{y}^{2}}\] \[\Rightarrow \]               \[y=\frac{a}{\sqrt{2}}\]


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