NEET AIPMT SOLVED PAPER MAINS 2012

  • question_answer
    A circular platform is mounted on a frictionless vertical axle. Its radius R = 2 m and its moment of inertia about the axle is\[200\text{ }kg\text{ }{{m}^{2}}\]. It is initially at rest. A 50 kg man stands on the edge of the platform and begins to walk along the edge at the speed of 1 \[m{{s}^{-1}}\] relative to the ground. Time taken by the man to complete one revolution is  

    A) \[\pi \sec \]       

    B) \[\frac{3\pi }{2}\sec \]  

    C) \[2\pi \sec \]     

    D) \[\frac{\pi }{2}\sec \]

    Correct Answer: C

    Solution :

    From conservation of angular momentum \[I\omega =mvr\] \[200\times \omega =50\times 2\times 1\] \[\omega =\frac{1}{2}rad/s\] \[v=r\omega =1m/s\] \[\therefore \]  \[T=\frac{2\pi r}{1-(-1)}=\frac{2\pi r}{2}=\pi r=2\pi s\]


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