2. Solved Papers
  3. BHU PMT

BHU PMT BHU PMT Solved Paper-2004

  • question_answer
    A circular disc is rotating with angular velocity \[\omega \]. If a man standing at the edge of the disc walks towards its centre, then the angular velocity of the disc will:                                                                               [BHU PMT-2004]

    A)  Decrease                           

    B)  Increase

    C)  Be halved                          

    D)  Not change

    Correct Answer: B

    Solution :

                     Key Idea: When no external force acts on a body its angular momentum remains conserved. From law of conservation of angular momentum, we have                                                 \[J=I\,\omega \,=\text{constant}\] Where \[I\] is moment of inertia of the body and \[\omega \]is angular velocity Also \[I=\frac{1}{2}M{{R}^{2}}\](for disc) where \[M\] is mass and \[R\] is radius of disc. \[\therefore \]                  \[J=\frac{1}{2}M{{R}^{2}}\,\omega =\text{constant}\] Since, man moves towards the center of the disc, distance of mass distribution \[R\] decreases hence, so \[\omega \] increases.


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