RAJASTHAN PMT Rajasthan - PMT Solved Paper-2004

  • question_answer
    The total energy of disc of mass M and velocity v rolling an inclined plane without slipping is:

    A)  \[\frac{3}{4}M{{\upsilon }^{2}}\]                             

    B)  \[\frac{2}{5}M{{\upsilon }^{2}}\]

    C)  \[\frac{3}{2}M{{\upsilon }^{2}}\]             

    D)         \[1\frac{1}{3}M{{\upsilon }^{2}}\]

    Correct Answer: A

    Solution :

    The total energy of a body rolling without slipping \[{{K}_{total}}={{K}_{rot}}+{{K}_{trans}}\]                                          \[=\frac{1}{2}I{{\omega }^{2}}+\frac{1}{2}M{{\upsilon }^{2}}\] But         \[I\,disc=\frac{1}{2}M{{r}^{2}}\,and\,\upsilon =r\omega \] \[\therefore \]  \[{{K}_{total}}=\frac{1}{2}\left( \frac{1}{2}M{{r}^{2}} \right){{\omega }^{2}}+\frac{1}{2}M{{(r\omega )}^{2}}\]                                          \[=\frac{1}{4}M{{r}^{2}}{{\omega }^{2}}+\frac{1}{2}M\,{{r}^{2}}{{\omega }^{2}}\]                                          \[=\frac{3}{4}M{{r}^{2}}{{\omega }^{2}}\]                           \[=\frac{3}{4}M{{\upsilon }^{2}}\]


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