JCECE Medical JCECE Medical Solved Paper-2011

  • question_answer
    By what percent the energy of a satellite has to be increased to shift it from an orbit of radius r to 3r?

    A)  22.3%          

    B)  33.3%

    C)  66.7%         

    D)    100%

    Correct Answer: C

    Solution :

     Binding energy of satellite in 1st case \[{{U}_{1}}=-\left( -\frac{GMm}{r}+\frac{1}{2}\frac{GMm}{r} \right)\] \[=\frac{GMm}{2r}\] Binding energy of satellite in 2nd case \[{{U}_{2}}=-\left[ -\frac{GMm}{3r}+\frac{1}{2}\frac{GMm}{3r} \right]\] \[=\frac{GMm}{6r}\] Energy increased \[\Delta E={{U}_{1}}-{{U}_{2}}\] \[=\frac{GMm}{r}\left[ \frac{1}{2}-\frac{1}{6} \right]\] \[=\frac{GMm}{3r}\] % increase in energy \[=\frac{\Delta E}{{{U}_{1}}}\times 100\] \[=\frac{GMm/3r}{GMm/2r}\times 100\] \[=66.7%\]


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