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  3. WB JEE Medical

WB JEE Medical WB JEE Medical Solved Paper-2013

  • question_answer
    A body of mass m taken from the earths surface to the height equal to twice the radius (R) of the earth. The change is potential energy of body will be

    A)  mg2R         

    B)  \[\frac{2}{3}mgR\]

    C)  3mgR        

    D)  \[\frac{1}{3}mgR\]

    Correct Answer: B

    Solution :

     Change in potential energy \[\Delta U=-\frac{GMm}{R+2R}-\left( -\frac{GMm}{R} \right)\] \[=-\frac{GMm}{3R}+\frac{GMm}{R}\] \[=\frac{2GMm}{3R}=\frac{2}{3}mg\,R\]  \[\left[ \because \,g=\frac{GM}{{{R}^{2}}} \right]\]


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