JIPMER Jipmer Medical Solved Paper-2002

  • question_answer
    If radius of the earth is reduced by 1% without changing its mass. The change in g will be:

    A)  2% decrease   

    B)        2% increase      

    C)         1% decrease   

    D)         1% increase

    Correct Answer: A

    Solution :

    From the relation of g \[g=\frac{GM}{{{R}^{2}}}\]  or  \[g\propto \frac{1}{{{R}^{2}}}\](at constant mass) As \[{{R}_{1}}=R,\]          \[{{R}_{2}}=R-\frac{R}{100}\] Hence,  \[\frac{{{g}_{2}}}{{{g}_{1}}}={{\left( \frac{{{R}_{r}}}{{{R}_{r}}} \right)}^{2}}\] \[\frac{{{g}_{2}}}{{{g}_{1}}}={{\left( \frac{R}{R-0.1R} \right)}^{2}}={{(1-0.01)}^{2}}\] As \[[{{(1+x)}^{n}}=1+nx\,\,\,\,\,\,\,where\,\,\left| x \right|<<1]\] or            \[\frac{{{g}_{2}}}{{{g}_{1}}}=1+0.02\] or \[\frac{{{g}_{2}}-{{g}_{1}}}{{{g}_{1}}}\times 100=[(1+0.02)-1]\times 100=2%\]


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