JEE Main & Advanced Physics Gravitation / गुरुत्वाकर्षण Question Bank Gravitation Potential

  • question_answer
    The gravitational potential energy of a body of mass ?m? at the earth?s surface \[-mg{{R}_{e}}\]. Its gravitational potential energy at a height \[{{R}_{e}}\] from the earth?s surface will be (Here \[{{R}_{e}}\] is the radius of the earth) [AIIMS 2000; MP PET 2000; Pb. PMT 2004]

    A)             \[-2\,mg{{R}_{e}}\]

    B)               \[2\,mg{{R}_{e}}\]

    C)             \[\frac{1}{2}mg{{R}_{e}}\]

    D)               \[-\frac{1}{2}mg{{R}_{e}}\]

    Correct Answer: D

    Solution :

                    \[\Delta U={{U}_{2}}-{{U}_{1}}=\frac{mgh}{1+\frac{h}{{{R}_{e}}}}=\frac{mg{{R}_{e}}}{1+\frac{{{R}_{e}}}{{{R}_{e}}}}=\frac{mg{{R}_{e}}}{2}\]             \[\,\Rightarrow \,{{U}_{2}}-(-mg{{R}_{e}})=\frac{mg{{R}_{e}}}{2}\]Þ          \[{{U}_{2}}=-\frac{1}{2}mg{{R}_{e}}\]


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