AMU Medical AMU Solved Paper-2003

  • question_answer
    To increase the period of a pendulum by 1C the length should be increased by percentage)                              

    A)  21                                         

    B)  11

    C)  10.5                                      

    D)  10

    Correct Answer: B

    Solution :

                     The time period (T) of pendulum is given by                 \[T=2\pi \sqrt{\frac{l}{g}}\] where \[l\] is length and g the acceleration due to gravity. \[\Rightarrow \]               \[{{T}^{2}}\propto l\] \[\therefore \]  \[\frac{T_{1}^{2}}{T_{2}^{2}}=\frac{l}{{{l}_{2}}}\] \[\Rightarrow \]               \[\frac{T_{2}^{2}-T_{1}^{2}}{T_{1}^{2}}=\frac{{{l}_{2}}-{{l}_{1}}}{{{l}_{1}}}\] \[\Rightarrow \]               \[\frac{1.1\times \Delta T}{T}=\frac{\Delta l}{l}\]. Hence, increase in length \[\frac{\Delta l}{l}\times 100=1.1\times \frac{\Delta T}{T}\times 100\]                 \[=1.1\times \frac{10}{100}\times 100=11%\]


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