Punjab Medical Punjab - MET Solved Paper-2005

  • question_answer
    A solid sphere, a hollow sphere and a disc having same mass and radius roll down the same inclined plane from rest. Which one will reach the ground in least time?

    A)  Solid sphere

    B)  Hollow sphere

    C)  Disc

    D)  All will reach in same time

    Correct Answer: A

    Solution :

    The acceleration of a body rolling down an inclined plane is                 \[a=\frac{g\sin \theta }{(1+I/M{{r}^{2}})}\] For solid sphere,                 \[I=\frac{2}{5}M{{R}^{2}}\] \[\therefore \]  \[a=\frac{5}{7}g\sin \theta \] For hollow sphere,                 \[I=\frac{2}{3}M{{R}^{2}}\] \[\therefore \]  \[a=\frac{3}{5}g\sin \theta \] For disc,\[I=\frac{1}{2}M{{R}^{2}}\]         \[\therefore \]  \[a=\frac{2}{3}g\sin \theta \] Acceleration is maximum for solid sphere hence, the solid sphere will reach the bottom in the least time.


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