JIPMER Jipmer Medical Solved Paper-2007

  • question_answer
    Imagine a new planet having the same density as that of earth but it is 3 times bigger than the earth in size. If the acceleration due to gravity on the surface of earth is g and that on the surface of the new planet is g, then

    A) \[g=3g\]  

    B)                        \[g=\frac{g}{9}\]              

    C)        \[g=9g\]             

    D)        \[g=27g\]

    Correct Answer: A

    Solution :

    The acceleration due to gravity on the new planet can be found using the relation \[g=\frac{GM}{{{R}^{2}}}\]                          ?(i) but \[M=\frac{4}{3}\pi {{R}^{3}}\rho ,\,\rho \] being density. Thus, Eq. (i) becomes \[\therefore \]  \[g=\frac{G\times \frac{4}{3}\pi {{R}^{3}}\rho }{{{R}^{2}}}\]                     \[=G\times \frac{4}{3}\pi R\rho \] \[\Rightarrow \]               \[g\propto R\] \[\therefore \,\,\,\,\,\,\,\,\frac{g}{g}=\,\frac{R}{R}\] \[\Rightarrow \,\,\,\,\,\,\,\,\frac{g}{g}=\frac{3R}{R}=3\] \[\Rightarrow \,\,\,\,\,\,\,\,g=3g\]


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