JEE Main & Advanced JEE Main Paper Phase-I Held on 07-1-2020 Morning

  • 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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