JCECE Medical JCECE Medical Solved Paper-2008

  • question_answer The mass of the earth is 6.00 x 1024 kg and that of the moon is \[7.40\times {{10}^{22}}kg.\] The constant of gravitation \[G=6.67\times {{10}^{-11}}\,N-{{m}^{2}}/k{{g}^{2}}.\]The potential   energy  of  the   system  is \[-7.79\times {{10}^{23}}\,J.\] The mean distance between the earth and moon is

    A) \[~3.80\times {{10}^{8}}m\]    

    B) \[~3.37\times {{10}^{6}}m\]

    C) \[~7.60\times {{10}^{4}}\text{ }m\]     

    D) \[~1.90\times {{10}^{2}}\text{ }m\]

    Correct Answer: A

    Solution :

     \[U=\frac{GMm}{r}\] \[\Rightarrow \] \[7.79\times {{10}^{28}}\] \[=\frac{6.67\times {{10}^{-11}}\times 7.4\times {{10}^{22}}\times 6\times {{10}^{24}}}{r}\] \[\Rightarrow \] \[r=3.8\times {{10}^{8}}\,m\]


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