DUMET Medical DUMET Medical Solved Paper-2004

  • question_answer
    The escape velocity from earth is\[11.2\,\,km\,{{s}^{-1}}\]. Another planet is having mass 1000 times and radius 10 times that of the earth, then escape velocity at that planet will be:

    A)  11.2 km/s    

    B)  112 km/s

    C)  1.12 km/s    

    D)  1120 km/s

    Correct Answer: B

    Solution :

     The escape velocity at earth is given by \[{{v}_{e}}=\sqrt{\frac{2\,G{{M}_{e}}}{{{R}_{e}}}}\]   where G is gravitational constant, \[{{M}_{e}}\]and \[{{R}_{e}}\]are mass and radius of earth respectively. \[\therefore \] \[{{v}_{p}}=\sqrt{\frac{2\,G{{M}_{p}}}{{{R}_{p}}}}\] (planet) Given, \[{{M}_{p}}=1000\,{{M}_{e}},\,{{R}_{p}}=10\,{{R}_{e}}\] \[\therefore \] \[\frac{{{v}_{p}}}{{{v}_{e}}}=\sqrt{\frac{2G\times 1000\,{{M}_{e}}}{10\,{{R}_{e}}}\times \frac{{{R}_{e}}}{2G{{M}_{e}}}}\] \[=\sqrt{100}=10\] \[\Rightarrow \] \[{{v}_{p}}=10\,{{v}_{e}}\] \[\Rightarrow \] \[{{v}_{p}}=10\times 11.2\] \[\Rightarrow \] \[{{v}_{p}}=112\,\,km/s\]


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