JCECE Medical JCECE Medical Solved Paper-2014

  • question_answer
    The change in the gravitational potential energy when a body of mass m is raised to a height \[nR\]above the surface of the earth is (here, R is the radius of the earth)

    A) \[\left( \frac{n}{n+1} \right)mgR\]

    B)  \[\left( \frac{n}{n-1} \right)mgR\]

    C)  \[nmgR\]

    D)  \[\frac{mgR}{n}\]

    Correct Answer: A

    Solution :

     Gravitational potential energy \[{{U}_{e}}=-\frac{GMm}{R}\] \[{{U}_{h}}=\frac{GMm}{(R+nR)}=-\frac{GMm}{R(n+1)}\] \[\Delta U={{U}_{h}}-{{U}_{e}}\] \[=\frac{GMm}{R}\left[ 1-\frac{1}{(n+1)} \right]\] \[=\frac{n}{(n+1)}\left[ \frac{GMm}{R} \right]\] \[=\frac{n}{(n+1)}mgR\]


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