J & K CET Medical J & K - CET Medical Solved Paper-2005

  • question_answer
    Two pendulums begin to swing simultaneously. If the ratio of the frequency of oscillations of the two is 7 : 8, then the ratio of lengths of the two pendulums will be :

    A)  7 : 8                                      

    B)  8 : 7

    C)  49 : 64                                 

    D)  64 : 49

    Correct Answer: D

    Solution :

                     The frequency of oscillation of pendulum of length\[l,\]is given by \[n=\frac{1}{2\pi }\sqrt{\frac{g}{l}}\] Given,\[{{n}_{1}}:{{n}_{2}}=7:8,\]then                 \[\frac{{{n}_{1}}}{{{n}_{2}}}=\sqrt{\frac{{{l}_{2}}}{{{l}_{1}}}}\] \[\Rightarrow \]               \[\frac{7}{8}=\sqrt{\frac{{{l}_{2}}}{{{l}_{1}}}}\] On squaring \[\Rightarrow \]               \[\frac{{{l}_{1}}}{{{l}_{2}}}=\frac{64}{49}\]


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