JCECE Engineering JCECE Engineering Solved Paper-2012

  • question_answer
    The mass of the moon is \[\frac{1}{81}\] of the earth but the gravitational pull is \[\frac{1}{6}\] of the earth. It is due to the fact that

    A)  the radius of earth is \[\frac{1}{6}\] of the moon

    B)  the radius of moon is \[\frac{9}{\sqrt{6}}\] of the earth

    C)  moon is the satellite of the earth

    D)   None of the above

    Correct Answer: A

    Solution :

    Gravitational pull depends upon the acceleration due to gravity on that planet.                 \[{{M}_{n}}=\frac{1}{81}{{M}_{e}},\,\,{{g}_{m}}=\frac{1}{6}{{g}_{e}}\] By the relation,\[g=\frac{GM}{{{R}^{2}}}\]                           \[\frac{{{R}_{e}}}{{{R}_{m}}}={{\left( \frac{{{M}_{e}}}{{{M}_{m}}}\times \frac{{{g}_{m}}}{{{g}_{e}}} \right)}^{\frac{1}{2}}}={{\left( 81\times \frac{1}{6} \right)}^{\frac{1}{2}}}\]


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