BCECE Engineering BCECE Engineering Solved Paper-2005

  • question_answer
    Consider the following statements: The total energy of a particle executing simple harmonic motion depends on its:
    (I) amplitude
    (II) period
    (III) displacement
    Of these statements:

    A) \[\text{I}\] and \[\text{II}\] are correct

    B) \[\text{II}\] and \[\text{III}\] are correct

    C) \[\text{I}\] and \[\text{III}\] are correct

    D) \[\text{I, II }and\,\text{III}\,are\,correct\]

    Correct Answer: A

    Solution :

    Key Idea: Total energy of a particle executing simple harmonic motion is obtained by summing its potential and kinetic energies. Potential energy of particle in SHM                 \[U=\frac{1}{2}m{{\omega }^{2}}{{x}^{2}}\] or            \[U=\frac{1}{2}m{{(2\pi f)}^{2}}{{x}^{2}}\] or            \[U=2{{\pi }^{2}}m{{f}^{2}}{{x}^{2}}\]                     ?(i) Kinetic energy of particle in SHM \[K=\frac{1}{2}m{{\omega }^{2}}({{A}^{2}}-{{x}^{2}})\]                 or            \[K=2{{\pi }^{2}}m{{f}^{2}}({{A}^{2}}-{{x}^{2}})\]              ?(ii) Hence, total energy \[E=K+U\] \[=2{{\pi }^{2}}m{{f}^{2}}{{x}^{2}}+2{{\pi }^{2}}m{{f}^{2}}({{A}^{2}}-{{x}^{2}})\] \[=2{{\pi }^{2}}m{{f}^{2}}{{A}^{2}}=\frac{2{{\pi }^{2}}m{{A}^{2}}}{{{T}^{2}}}\] \[\left( \because \,T=\frac{1}{f} \right)\] Thus, it is obvious that total energy of particle executing simple harmonic motion depends on amplitude (A) and period (T). \[\text{II}\] and \[\text{III}\] are correct


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