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JEE Main & Advanced Physics Rotational Motion Question Bank Mock Test - Dynamics of Rigid Body

  • question_answer
    A child is standing with folded hands at the centre of a platform rotating about its central axis. The kinetic energy of the system is K. The child now stretches his arms so that the moment of inertia of the system doubles. The kinetic energy of the system now is

    A) \[2K\]              

    B) \[\frac{K}{2}\]

    C) \[\frac{K}{4}\]             

    D) \[4K\]

    Correct Answer: B

    Solution :

    [b]  \[KE=,\frac{{{L}^{2}}}{2I}\,\,\,\,\,L\] remains constant. \[I\] Doubles so KE becomes half.


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