AMU Medical AMU Solved Paper-2012

  • question_answer
    The imaginary angular velocity of the earth for which the effective acceleration due to gravity at the equator shall be zero is equal to

    A)                  \[1.25\times {{10}^{-3}}\] rad/s               

    B)                  \[2.50\times {{10}^{-3}}\] rad/s

    C)                  \[3.75\times {{10}^{-3}}\] rad/s               

    D)                  \[5.0\times {{10}^{-3}}\] rad/s

    Correct Answer: B

    Solution :

                    Acceleration due to gravity                 \[g=g-{{\omega }^{2}}R{{\cos }^{2}}\lambda \]                 \[0=g-{{\omega }^{2}}R{{\cos }^{2}}{{60}^{o}}\]                 \[0=g-\frac{{{\omega }^{2}}R}{4}\]                 \[\omega =2\sqrt{\frac{g}{R}}=2\sqrt{\frac{10}{6400\times 100}}\] Angular velocity \[\omega =\frac{1}{400}\]                 \[=2.5\times {{10}^{-3}}\] rad/s                 (Take \[g=10\,\,m/{{s}^{2}}\] for the acceleration due to gravity if the earth were at rest and radius of earth equal to 6400 km.)


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