BHU PMT BHU PMT (Screening) Solved Paper-2007

  • question_answer
    The potential energy of a simple harmonic oscillator when the particle is half way to its end point is

    A)  \[\frac{1}{4}E\]                               

    B)  \[\frac{1}{2}E\]

    C)  \[\frac{2}{3}E\]                               

    D)  \[\frac{1}{8}E3\] (where E is the total energy)

    Correct Answer: A

    Solution :

                     Potential energy of a simple harmonic oscillator \[U=\frac{1}{2}m{{\omega }^{2}}{{y}^{2}}\] Kinetic energy of a simple harmonic oscillator \[K=\frac{1}{2}m{{\omega }^{2}}({{A}^{2}}-{{y}^{2}})\] Here, y = displacement from mean position A = maximum displacement from mean position (or amplitude) Total energy, \[E=U+K\]                 \[=\frac{1}{2}m{{\omega }^{2}}{{y}^{2}}+\frac{1}{2}m{{\omega }^{2}}({{A}^{2}}-{{y}^{2}})\]                 \[=\frac{1}{2}m{{\omega }^{2}}{{A}^{2}}\] When the particle is halfway to its end point ie, at half of its amplitude, then                 \[y=\frac{A}{2}\] Hence, potential energy                 \[U=\frac{1}{2}m{{\omega }^{2}}{{\left( \frac{A}{2} \right)}^{2}}\]                 \[=\frac{1}{4}\left( \frac{1}{2}m{{\omega }^{2}}{{A}^{2}} \right)\]                 \[U=\frac{E}{4}\]


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