BCECE Engineering BCECE Engineering Solved Paper-2006

  • question_answer
    The motion of a particle varies with time according to the relation \[y=a(\sin \,\omega t\,+\cos \,\omega t).\]

    A)  The motion is oscillatory but not SHM

    B)         The motion is SHM with amplitude \[a\]

    C)         The motion is SHM with amplitude \[\alpha \sqrt{2}\]

    D)         The motion is SHM with amplitude \[2\alpha \]

    Correct Answer: C

    Solution :

    Key Idea: Rearrange the given equation of particle motion. The given equation is written as \[y=a(sin\omega t+cos\omega t)\]                 or            \[y=a\sqrt{2}\left( \frac{1}{\sqrt{2}}\sin \omega t+\frac{1}{\sqrt{2}}\cos \omega t \right)\]                 or     \[y=a\sqrt{2}\left[ \cos \frac{\pi }{4}\sin \omega t+\sin \frac{\pi }{4}\cos \omega t \right]\]                 or            \[y=a\sqrt{2}\sin (\omega t+\pi /4)\] Thus, we have seen that the particles motion is simple harmonic with amplitude \[a\sqrt{2}.\] Note: We can represent the resultant equation in angular from as \[\theta ={{\theta }_{0}}sin(\omega t+\pi /4)\] where\[{{\theta }_{0}}\]is amplitude of angular SHM of particle.


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