JEE Main & Advanced Physics Two Dimensional Motion Question Bank Non-uniform Circular Motion

  • question_answer
    The maximum and minimum tension in the string whirling in a circle of radius 2.5 m with constant velocity are in the ratio 5 : 3 then its velocity is                                   [Pb. PET 2003]

    A)             \[\sqrt{98}\,\,m/s\]

    B)                    \[7\,\,m/s\]

    C)                 \[\sqrt{490}\,\,m/s\]

    D)                             \[\sqrt{4.9}\]

    Correct Answer: A

    Solution :

                    In this problem it is assumed that particle although moving in a vertical loop but its speed remain constant. Tension at lowest point \[{{T}_{\max }}=\frac{m{{v}^{2}}}{r}+mg\] Tension at highest point \[{{T}_{\min }}=\frac{m{{v}^{2}}}{r}-mg\] \[\frac{{{T}_{\max }}}{{{T}_{\min }}}=\frac{\frac{m{{v}^{2}}}{r}+mg}{\frac{m{{v}^{2}}}{r}-mg}=\frac{5}{3}\] by solving we get,\[v=\sqrt{4gr}\]\[=\sqrt{4\times 9.8\times 2.5}\]    \[=\sqrt{98}\,m/s\]


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