AMU Medical AMU Solved Paper-2003

  • question_answer
    The angular velocity of earth at present is \[\omega \]  With what angular velocity should it rotate \[\omega \] that weight of a body at the equator appears\[\omega \] be zero?

    A)  289\[\omega \]                               

    B)  17\[\omega \]

    C)  8\[\omega \]                                   

    D)  2\[\omega \]

    Correct Answer: B

    Solution :

                     The body will appear weightless only when the centripetal force equals the weight of the body. \[\therefore \]  \[\frac{m{{v}^{2}}}{R}=mg\] Since,    \[v=R\,\omega \] \[\therefore \]  \[\frac{m\,{{(R\omega )}^{2}}}{R}=mg\] \[\Rightarrow \]               \[mR{{\omega }^{2}}=mg\] \[\Rightarrow \]               \[\omega =\sqrt{\frac{g}{R}}\] Standard value \[(\omega )\] at present is                 \[\omega =\frac{2\pi }{T}=\frac{2\pi }{86400}rad\,{{s}^{-1}}\]                 \[=7.3\times {{10}^{-5}}rad\,{{s}^{-1}}\] and        \[\omega =\sqrt{\frac{g}{R}}\]                 \[=\sqrt{\frac{9.8}{6.4\times {{10}^{6}}}}=1.2\times {{10}^{-3}}\] \[\therefore \]  \[\omega \approx 17\,\omega \].


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