JEE Main & Advanced Physics Two Dimensional Motion Question Bank Uniform Circular Motion

  • question_answer
    A bob of mass 10 kg is attached to wire 0.3 m long.  Its breaking stress is 4.8 × 107 N/m2.  The area of cross section of the wire is 10?6 m2.  The maximum angular velocity with which it can be rotated in a horizontal circle [Pb. PMT 2001]

    A)             8 rad/sec

    B)                      4 rad/sec

    C)             2 rad/sec

    D)                      1 rad/sec

    Correct Answer: B

    Solution :

                    Centripetal force = breaking force             Þ\[m{{\omega }^{2}}r=\]breaking stress ´ cross sectional area             Þ\[m{{\omega }^{2}}r=p\times A\] Þ \[\omega =\sqrt{\frac{p\times A}{mr}}=\sqrt{\frac{4.8\times {{10}^{7}}\times {{10}^{-6}}}{10\times 0.3}}\]             \ \[\omega =4\,rad/\sec \]


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