RAJASTHAN ­ PET Rajasthan PET Solved Paper-2005

  • question_answer
    A body of mass m is taken from earth surface to the height A equal to radius of earth, the increase in potential energy will be

    A)  \[\frac{mgR}{2}\]

    B)  \[mgR\]

    C)  \[2mgR\]

    D)  \[\frac{1}{4}mgR\]

    Correct Answer: A

    Solution :

     The potential energy on surface of earth \[U=\frac{-G{{M}_{e}}m}{R}\] The potential energy at height R from surface of earth \[U=\frac{-G{{M}_{e}}m}{2R}\] \[\therefore \] \[\Delta U=U'-U\] \[=\frac{G{{M}_{e}}m}{2R}=\frac{g{{R}^{2}}m}{2R}-\frac{mgR}{2}\]


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