Railways RRB (Assistant Loco Pilot & Technician) Solved Paper-2 (2014)

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

    A)  \[2\,a\]                        

    B)  a

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

    D)  \[\frac{a}{\sqrt{2}}\]

    Correct Answer: D

    Solution :

    In SHM, KE=\[=\frac{1}{2}m\,({{a}^{2}}-{{y}^{2}}){{\omega }^{2}}\] \[PE=\frac{1}{2}m{{\omega }^{2}}{{y}^{2}}\] They are equal if             \[\frac{1}{2}m{{\omega }^{2}}({{a}^{2}}-{{y}^{2}})=\frac{1}{2}m{{\omega }^{2}}{{y}^{2}}\] \[\Rightarrow \]            \[{{a}^{2}}-{{y}^{2}}={{y}^{2}}\] \[\Rightarrow \]            \[2{{y}^{2}}={{a}^{2}}\] \[\therefore \]    \[y=\frac{a}{\sqrt{2}}\]


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