AMU Medical AMU Solved Paper-2006

  • question_answer
    The ratio of radii of gyration of a circular disc and a circular ring of the same radii and same mass about a tangential axis in the plane is

    A)  1 : 2                                      

    B)  \[\sqrt{5}:\sqrt{6}\]

    C)  2 : 3                                      

    D)  2 : 1

    Correct Answer: B

    Solution :

                     \[{{I}_{ring}}=\frac{m{{r}^{2}}}{2}+m{{r}^{2}}=\frac{3}{2}m{{r}^{2}}\] \[{{I}_{disc}}=\frac{m{{r}^{2}}}{4}+m{{r}^{2}}=\frac{5}{4}m{{r}^{2}}\] \[\frac{{{I}_{disc}}}{{{I}_{ring}}}=\frac{\frac{5\,m{{r}^{2}}}{4}}{\frac{3}{2}m{{r}^{2}}}=\frac{5}{6}\]                                 \[\frac{mK_{disc}^{2}}{mK_{ring}^{2}}=\frac{5}{6}\]                 \[\Rightarrow \]               \[\frac{K_{disc}^{2}}{K_{ring}^{2}}=\sqrt{\frac{5}{6}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner