JCECE Engineering JCECE Engineering Solved Paper-2007

  • question_answer
    For a satellite moving in an orbit around the earth, the ratio of kinetic energy to potential energy is

    A) \[2\]                                     

    B)  \[\frac{1}{2}\]

    C)  \[\frac{1}{\sqrt{2}}\]                                    

    D)  \[\sqrt{2}\]

    Correct Answer: B

    Solution :

    Key Idea: Kinetic energy of satellite is half of its potential energy. Potential energy of satellite                 \[U=-\frac{G{{M}_{e}}m}{{{R}_{e}}}\] where \[{{R}_{e}}\] is radius of earth, \[{{M}_{e}}\] the mass of earth, \[m\] the mass of satellite and \[G\] the gravitational constant.                 \[|U|\,\,=\frac{G{{M}_{e}}m}{{{R}_{e}}}\] Kinetic energy of satellite                 \[K=\frac{1}{2}\frac{G{{M}_{e}}m}{{{R}_{e}}}\] Thus      \[\frac{K}{|U|}=\frac{1}{2}\frac{G{{M}_{e}}m}{{{R}_{e}}}\frac{{{R}_{e}}}{G{{M}_{e}}m}\]                         \[=\frac{1}{2}\]


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