J & K CET Medical J & K - CET Medical Solved Paper-2000

  • question_answer
    Let the value of acceleration due to gravity at poles and equator of earth \[{{g}_{p}}\]and \[{{g}_{e}}\]respectively. Assuming the earth to be a sphere of radius R rotating about its axis with angular speed \[\omega \] then \[{{g}_{p}}-\text{ }{{g}_{e}}\] is given by :

    A) \[\frac{{{\omega }^{2}}}{R}\]                                     

    B) \[R{{\omega }^{2}}\]

    C) \[{{R}^{2}}{{\omega }^{2}}\]                                      

    D) \[\frac{{{\omega }^{2}}}{{{R}^{2}}}\]

    Correct Answer: B

    Solution :

                    Effective value of acceleration due to gravity \[({{g}_{\phi }})\] is given by \[{{g}_{\phi }}=g\left( 1-\frac{{{\omega }^{2}}R}{g}{{\cos }^{2}}\phi  \right)\]where\[\omega \]is angular velocity. At poles:              \[\phi =90{}^\circ \] \[\therefore \]  \[{{g}_{\phi }}={{g}_{p}}=g\]                                       ?. (i) At equator    \[\phi =0\] \[{{g}_{\phi }}={{g}_{e}}=g\left( 1-\frac{{{\omega }^{2}}R}{g} \right)=g-{{\omega }^{2}}R\]           ?.. (ii) From Eqs. (i) and (ii), we get \[\therefore \] \[{{g}_{p}}-{{g}_{e}}=g-(g-{{\omega }^{2}}R)={{\omega }^{2}}R\]


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