JEE Main & Advanced Physics Simple Harmonic Motion Question Bank Energy of Simple Harmonic Motion

  • question_answer
    A particle starts simple harmonic motion from the mean position. Its amplitude is a and total energy E. At one instant its kinetic energy is \[3E/4.\] Its displacement at that instant is [Kerala PET 2005]

    A)            \[1/\sqrt{2}\]                            

    B)            \[a/2\]

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

    D)            \[a/\sqrt{3}\]

    Correct Answer: B

    Solution :

             \[\frac{K}{E}=\frac{\frac{1}{2}m{{\omega }^{2}}({{a}^{2}}-{{y}^{2}})}{\frac{1}{2}m{{\omega }^{2}}{{a}^{2}}}=\frac{{{a}^{2}}-{{y}^{2}}}{{{a}^{2}}}=1-\frac{{{y}^{2}}}{{{a}^{2}}}\] So, \[\frac{\left( \frac{3E}{4} \right)}{E}=1-\frac{{{y}^{2}}}{{{a}^{2}}}\Rightarrow \frac{{{y}^{2}}}{{{a}^{2}}}=1-\frac{3}{4}=\frac{1}{4}\]\[\Rightarrow \]\[y=\frac{a}{2}\].


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