JEE Main & Advanced Physics Simple Harmonic Motion Question Bank Simple Pendulum

  • question_answer
    A simple pendulum is executing simple harmonic motion with a time period T. If the length of the pendulum is increased by 21%, the percentage increase in the time period of the pendulum of increased length is [BHU 1994, 96; Pb. PMT 1995; AFMC 2001; AIIMS 2001; AIEEE 2003]

    A)            10%                                          

    B)            21%

    C)            30%                                          

    D)            50%

    Correct Answer: A

    Solution :

                       If initial length \[{{l}_{1}}=100\] then \[{{l}_{2}}=121\]                    By using \[T=2\pi \sqrt{\frac{l}{g}}\Rightarrow \frac{{{T}_{1}}}{{{T}_{2}}}=\sqrt{\frac{{{l}_{1}}}{{{l}_{2}}}}\]                    Hence, \[\frac{{{T}_{1}}}{{{T}_{2}}}=\sqrt{\frac{100}{121}}\Rightarrow {{T}_{2}}=1.1\,{{T}_{1}}\]            % increase = \[\frac{{{T}_{2}}-{{T}_{1}}}{{{T}_{1}}}\times 100=10\,%\]


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