NEET Physics Simple Harmonic Motion NEET PYQ-Simple Harmonic Motion

  • question_answer
    A particle is executing SHM along a straight line. Its velocities at distances \[{{x}_{1}}\] and \[{{x}_{2}}\] from the mean position are \[{{v}_{1}}\] and \[{{v}_{2}},\] respectively. Its time period is                         [NEET  2015]

    A)  \[2\pi \sqrt{\frac{x_{1}^{2}+x_{2}^{2}}{v_{1}^{2}+v_{2}^{2}}}\]           

    B)       \[2\pi \sqrt{\frac{x_{2}^{2}-x_{1}^{2}}{v_{1}^{2}-v_{2}^{2}}}\]

    C)  \[2\pi \sqrt{\frac{v_{1}^{2}+v_{2}^{2}}{x_{1}^{2}+x_{2}^{2}}}\]           

    D)       \[2\pi \sqrt{\frac{v_{1}^{2}-v_{2}^{2}}{x_{1}^{2}-x_{2}^{2}}}\]

    Correct Answer: B

    Solution :

    Let A be the amplitude of oscillation then
    \[v_{1}^{2}={{\omega }^{2}}({{A}^{2}}-x_{1}^{2})\,\,\]   …(i)
    \[v_{2}^{2}={{\omega }^{2}}({{A}^{2}}-{{x}^{2}})\,\,\,\] …(ii)
    Subtracting Eq. (ii) from Eq. (i), we get
    \[v_{1}^{2}-v_{2}^{2}={{\omega }^{2}}(x_{2}^{2}-x_{1}^{2})\]
    \[\Rightarrow \]   \[\omega =\sqrt{\frac{v_{1}^{2}-v_{2}^{2}}{x_{2}^{2}-x_{1}^{2}}}\]
    \[\Rightarrow \]   \[\frac{2\pi }{T}=\sqrt{\frac{v_{1}^{2}-v_{2}^{2}}{x_{2}^{2}-x_{1}^{2}}}\]
    \[\Rightarrow \]   \[T=2\pi \sqrt{\frac{x_{2}^{2}-x_{1}^{2}}{v_{1}^{2}-v_{2}^{2}}}\]


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