NEET Sample Paper NEET Sample Test Paper-15

  • question_answer A man measures time period of a pendulum (T) in stationary lift. If the lift moves upwards with acceleration g/4, then the new time period will be:

    A) \[\frac{2T}{\sqrt{5}}\]                                   

    B) \[\left( \frac{\sqrt{5T}}{2} \right)\]

    C) \[\frac{\sqrt{5}}{(2T)}\]                    

    D)  \[\frac{2}{\sqrt{5T}}\]

    Correct Answer: A

    Solution :

    Let the new time period be T? The effective value of g for the accelerating lift will be \[g+g/4=5g/4\] \[T=2\pi \sqrt{\frac{\ell }{g}}\]and \[T'=2\pi \sqrt{\frac{\ell }{\frac{5g}{4}}}\] \[\therefore \]    \[\frac{T'}{T}=\sqrt{\frac{4}{5}}=\frac{2}{\sqrt{5}}\]or \[T'=\frac{2T}{\sqrt{5}}\] Hence, the correction option is [a].

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