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9th Class Science Gravitation and Floatation Question Bank Gravitation

  • question_answer
    Ratio of the radius of the earth to that of the moon is 10. Ratio of g on the earth to the moon is 6. Then ratio of the escape velocity from the earth's surface to that from the moon is approximately

    A)  2                            

    B)         4

    C)  8                              

    D)         8

    Correct Answer: C

    Solution :

     Escape velocity,\[{{v}_{e}}=\sqrt{2gR}\] For moon,\[{{v}_{e,\,\,moon}}=\sqrt{2gR}\] For earth,\[{{y}_{e,\,\,moon}}=\sqrt{2\times 6g\times 10R}\] \[\therefore \]  \[=\frac{{{v}_{e}}\,\,\,earth)}{{{v}_{e}}(moon)}=\frac{\sqrt{60(2gR)}}{2grR}=\sqrt{60}\approx \mathbf{8}\]


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