JEE Main & Advanced Physics Rotational Motion JEE PYQ-Rotational Motion

  • question_answer
    The radius of gyration of a uniform rod of length l, about an axis passing through a point \[\frac{l}{\text{4}}\] away from the centre of the rod, and perpendicular to it, is:                                   [JEE MAIN Held on 07-01-2020 Morning]

    A)         \[\sqrt{\frac{\text{7}}{\text{48}}}l\]     

    B)        \[\frac{\text{1}}{\text{8}}l\]

    C)   \[\frac{1}{4}l\]            

    D)        \[\sqrt{\frac{\text{3}}{\text{8}}}l\]

    Correct Answer: A

    Solution :

    [a]
                \[\text{l=}\frac{M{{l}^{2}}}{12}+M\times \left( \frac{{{l}^{2}}}{16} \right)=\frac{7M{{l}^{2}}}{48}\]
                \[\therefore M{{K}^{2}}=\frac{7M{{l}^{2}}}{48}\]
                \[\Rightarrow K=\sqrt{\frac{7}{48}}l\]


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