J & K CET Medical J & K - CET Medical Solved Paper-2001

  • question_answer
    A body executes simple harmonic motion with amplitude a. At what displacement from the equilibrium position is its energy half kinetic and half potential?

    A) \[\frac{a}{2}\]                                   

    B) \[\frac{a}{\sqrt{2}}\]

    C)  \[\sqrt{2a}\]                                     

    D) \[\frac{a}{3}\]

    Correct Answer: B

    Solution :

                    The kinetic energy (KE) of a body executing SHM with amplitude a undergoing displace- ment y is \[KE=\frac{1}{2}m{{\omega }^{2}}({{a}^{2}}-{{y}^{2}})\]          ...(i) where\[\omega \]is angular velocity, and m the mass. Also, potential energy (PE) is \[PE=\frac{1}{2}m{{\omega }^{2}}{{y}^{2}}\]                        ...(ii) Given,     \[KE=PE\] \[\therefore \]  \[\frac{1}{2}m{{\omega }^{2}}({{a}^{2}}-{{y}^{2}})=\frac{1}{2}m{{\omega }^{2}}{{y}^{2}}\] \[\Rightarrow \]               \[{{a}^{2}}-{{y}^{2}}={{y}^{2}}\] \[\Rightarrow \]               \[y=\frac{a}{\sqrt{2}}\]


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