BCECE Medical BCECE Medical Solved Papers-2011

  • question_answer
    A round disc of moment of inertia  \[{{I}_{2}}\] about its axis perpendicular to its plane and passing through its centre is placed over another disc of moment of inertia \[{{l}_{1}}\] rotating with an angular velocity co about the same axis. The final angular velocity of the combination of discs is

    A)  \[\frac{{{I}_{2}}\,\,\omega }{{{I}_{1}}+{{I}_{2}}}\]

    B)  \[\omega \]

    C)  \[\frac{{{I}_{1}}\,\,\omega }{{{I}_{1}}+{{I}_{2}}}\]

    D)  \[\frac{({{I}_{1}}+{{I}_{2}})\,\omega }{{{I}_{1}}}\]

    Correct Answer: C

    Solution :

    According to conservation of angular momentum                 \[{{I}_{1}}{{\omega }_{1}}={{I}_{2}}{{\omega }_{2}}\] \[\Rightarrow \] \[{{I}_{1}}\omega =({{I}_{1}}+{{I}_{2}}){{\omega }_{2}}\] \[\Rightarrow \] \[{{\omega }_{2}}=\frac{{{I}_{1}}\omega }{{{I}_{1}}+{{I}_{2}}}\]


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