Manipal Medical Manipal Medical Solved Paper-2006

  • question_answer
    A coin is dropped in a lift. It takes time\[{{t}_{1}}\]to reach the floor when lift is stationary. It takes time\[{{t}_{2}}\]when lift is moving up with constant acceleration. Then:

    A)  \[{{t}_{1}}>{{t}_{2}}\]

    B)  \[{{t}_{2}}>{{t}_{1}}\]

    C)  \[{{t}_{1}}={{t}_{2}}\]

    D)  \[{{t}_{1}}>>{{t}_{2}}\]

    Correct Answer: A

    Solution :

     Time taken by coin to reach the floor is given by \[h=\frac{1}{2}g{{t}^{2}}\] \[(\because u=0)\] \[\Rightarrow \] \[t=\sqrt{\frac{2h}{g}}\] In stationary lift, \[{{t}_{1}}=\sqrt{\frac{2h}{g}}\] In upward moving lift with constant acceleration a, \[g=g+a\] \[\therefore \] \[{{t}_{2}}=\sqrt{\frac{2h}{g+a}}\] Clearly,        \[g>\text{ }g\] Thus,         \[{{t}_{2}}\text{}\,{{\text{t}}_{1}}\]


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