JCECE Engineering JCECE Engineering Solved Paper-2013

  • question_answer
    If two springs of spring constants \[{{k}_{1}}\] and \[{{k}_{2}}\] while executing \[SHM\] have equal highest velocities, then the ratio of their amplitudes will be (their masses are in ratio\[1:2)\]

    A) \[\sqrt{2{{k}_{2}}/{{k}_{1}}}\]                   

    B) \[\sqrt{2{{k}_{1}}/{{k}_{2}}}\]

    C)  \[2{{k}_{1}}/{{k}_{2}}\]                

    D)  \[2{{k}_{2}}/{{k}_{1}}\]

    Correct Answer: A

    Solution :

    Given,\[{{m}_{2}}=2{{m}_{1}}\] For a loaded spring, the angular frequency                 \[\omega =\sqrt{k/m}\] \[\therefore \]  \[\frac{{{\omega }_{1}}}{{{\omega }_{2}}}=\sqrt{\frac{{{k}_{1}}}{{{k}_{2}}}\times \frac{{{m}_{2}}}{{{m}_{1}}}}=\sqrt{\frac{{{k}_{1}}}{{{k}_{2}}}\times 2}\] For equal maximum velocity,\[{{A}_{1}}{{\omega }_{1}}={{A}_{2}}{{\omega }_{2}}\] we have,             \[\frac{1}{8}={{e}^{-4.36}}\]\[\frac{{{A}_{1}}}{{{A}_{2}}}=\frac{{{\omega }_{2}}}{{{\omega }_{1}}}=\sqrt{\frac{{{k}_{2}}}{{{k}_{1}}}\times 2}=\sqrt{\frac{2{{k}_{2}}}{{{k}_{1}}}}\]


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