JEE Main & Advanced Sample Paper JEE Main - Mock Test - 39

  • question_answer
    Let \[{{T}_{1}}\] and \[{{T}_{2}}\] be the time periods of two springs A and B when a mass m is suspended from them separately. Now both the springs are connected in parallel and same mass m is suspended with them. Now let T be the time period in this position. Then -

    A) \[T={{T}_{1}}+{{T}_{2}}\]    

    B)        \[T=\frac{{{T}_{1}}{{T}_{2}}}{{{T}_{1}}+{{T}_{2}}}\]

    C) \[{{T}^{2}}={{T}_{1}}^{2}+{{T}_{2}}^{2}\]

    D)        \[\frac{1}{{{T}^{2}}}=\frac{1}{{{T}_{1}}^{2}}+\frac{1}{{{T}_{2}}^{2}}\]

    Correct Answer: D

    Solution :

    [d] \[{{T}_{1}}=2\pi \sqrt{\frac{m}{{{k}_{1}}}}\Rightarrow {{k}_{1}}=\frac{4{{\pi }^{2}}m}{T_{2}^{2}}\] \[{{T}_{2}}=2\pi \sqrt{\frac{m}{{{k}_{2}}}}\Rightarrow {{k}_{2}}=\frac{4{{\pi }^{2}}m}{T_{2}^{2}}\] Now \[T=2\pi \sqrt{\frac{m}{k}}\]           \[k=\frac{4{{\pi }^{2}}m}{{{T}^{2}}}\] in parallel \[k={{k}_{1}}+{{k}_{2}}.\]


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