Haryana PMT Haryana PMT Solved Paper-2002

  • question_answer
    In simple harmonic motion, when the    displacement is one half of the amplitude,           what fraction of the total energy is kinetic :

    A)  zero                                     

    B)  \[\frac{1}{2}\]

    C)  \[\frac{1}{4}\]                                  

    D)  \[\frac{3}{4}\]

    Correct Answer: C

    Solution :

                    Total energy \[E=\frac{1}{2}m\,\,{{\omega }^{2}}\,{{a}^{2}}\] \[K.E.=\frac{1}{2}m\,{{\omega }^{2}}\,{{y}^{2}}\] According to question \[y=\frac{a}{2}\]                                 \[=\frac{1}{2}m\,\,{{\omega }^{2}}{{a}^{2}}{{\left( \frac{y}{2} \right)}^{2}}\]                                 \[=\frac{1}{2}m\,\,{{\omega }^{2}}\frac{{{a}^{2}}}{4}\]                                 \[=\frac{1}{4}\left( \frac{1}{2}m\,{{\omega }^{2}}\,{{a}^{2}} \right)=\frac{1}{4}E\] Therefore, K.E, is \[\frac{1}{4}\] .times of total energy.


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