CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2007

  • question_answer
    A particle executes simple harmonic motion with a time period of 16 s. At time\[t=2\text{ }s,\]the particle crosses the mean position while at \[t=4s,\]its velocity is\[4\text{ }m{{s}^{-1}}\]. The amplitude of motion in metre is

    A)  \[\sqrt{2}\pi \]

    B)         \[16\sqrt{2}\pi \]            

    C)  \[24\sqrt{2}\pi \]            

    D)  \[\frac{4}{\pi }\]

    E)  \[\frac{32\sqrt{2}}{\pi }\]

    Correct Answer: E

    Solution :

    For simple harmonic motion, \[y=a\sin \omega t\] \[\therefore \]  \[y=a\sin \left( \frac{2\pi }{T} \right)t\]  \[(at\,t=2s)\] \[{{y}_{1}}=a\sin \left[ \left( \frac{2\pi }{16} \right)\times 2 \right]\] \[=a\sin \left( \frac{\pi }{4} \right)=\frac{a}{\sqrt{2}}\]   ?(i) At\[t=4\text{ }s\]or after 2 s from mean position, \[{{y}_{1}}=\frac{a}{\sqrt{2}},velocity=4\,m{{s}^{-1}}\] \[\therefore \] \[Velocity=\omega \sqrt{{{a}^{2}}-y_{1}^{2}}\] or \[4=\left( \frac{2\pi }{16} \right)\sqrt{{{a}^{2}}-\frac{{{a}^{2}}}{2}}\]  [from Eq. (i)] or            \[4=\frac{\pi }{8}\times \frac{a}{\sqrt{2}}\] or            \[a=\frac{32\sqrt{2}}{\pi m}\]


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