CET Karnataka Medical CET - Karnataka Medical Solved Paper-2015

  • question_answer
    The ratio of kinetic energy to the potential energy of a particle executing SHM at a distance equal to half its amplitude, the distance being measured from its equilibrium position is

    A)  \[4:1\]   

    B)  \[8:1\]

    C)  \[3:1\]  

    D)  \[2:1\]

    Correct Answer: C

    Solution :

    : The kinetic energy of the particle executing SHM at a distance x from its equilibrium position is       \[K=\frac{1}{2}m{{\omega }^{2}}({{A}^{2}}-{{x}^{2}})\] and the potential energy is \[U=\frac{1}{2}m{{\omega }^{2}}{{x}^{2}}\] where A is the amplitude, co is the angular frequency and M is the mass of the body. At \[x=\frac{A}{2}\] \[K=\frac{1}{2}m{{\omega }^{2}}\left( {{A}^{2}}-{{\left( \frac{A}{2} \right)}^{2}} \right)\] and  \[U=\frac{1}{2}m{{\omega }^{2}}{{\left( \frac{A}{2} \right)}^{2}}\] Their corresponding ratio is \[\frac{K}{U}=\frac{\frac{1}{2}m{{\omega }^{2}}\left( {{A}^{2}}-{{\left( \frac{A}{2} \right)}^{2}} \right)}{\frac{1}{2}m{{\omega }^{2}}{{\left( \frac{A}{2} \right)}^{2}}}=\frac{\left( {{A}^{2}}-\frac{{{A}^{2}}}{4} \right)}{\frac{{{A}^{2}}}{4}}\] \[=\frac{\frac{3}{4}{{A}^{2}}}{\frac{{{A}^{2}}}{4}}=\frac{3}{1}\]


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