JEE Main & Advanced Sample Paper JEE Main Sample Paper-22

  • question_answer
    Find the minimum time at which ratio of kinetic energy to potential energy of a particle is 3. The particle starts SHM from its equilibrium position. T is the time period of oscillation.

    A)  T/6                             

    B)  T/12         

    C)  T/8                             

    D)  T/24         

    Correct Answer: B

    Solution :

    \[KE=\,3PE\] \[KE=\frac{1}{2}m{{v}^{2}}=\frac{1}{2}m{{\omega }^{2}}({{A}^{2}}-{{x}^{2}})\] \[PE=\frac{1}{2}m{{\omega }^{2}}{{x}^{2}}\] \[({{A}^{2}}-{{x}^{2}})\,=3{{x}^{2}}\] \[x=A/2\] At t = 0, y = 0 so \[\phi =0\] \[x=A\sin \,\omega t\,=A\sin \,\left( \frac{2\pi }{T}\times t \right)\] \[x=A/2\,\,\,for\,\,t=T/12\] \[({{A}^{2}}-{{x}^{2}})\,=3{{x}^{2}}\] \[x=A/2\] At \[t=0,\,\,y=0,\] so \[\phi =0\] \[x=A\sin \,\omega t\,=A\sin \left( \frac{2\pi }{T}\times t \right)\] \[x=A/2\,\] For \[t=T/12\]


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