JIPMER Jipmer Medical Solved Paper-1997

  • question_answer
    An object weighs 700 N on earth. What will be weight on a planet having 1/7 the of earth mass and half of earths radius:

    A)  400 N                                   

    B)  300 N                   

    C)  200 N                   

    D)         100 N

    Correct Answer: A

    Solution :

    Here: weight of object on earth \[{{\omega }_{e}}=700\,N\] Mass of the planet \[{{M}_{p}}=\frac{{{M}_{e}}}{7}\]            (where \[{{M}_{e}}\] is mass of earth) Radius of planet \[{{R}_{p}}=\frac{{{R}_{e}}}{2}\]                                 (where \[{{R}_{e}}\] is radius of earth) From the formula \[g=\frac{GM}{{{R}^{2}}}\propto \frac{M}{{{R}^{2}}}\] Hence, \[\frac{{{g}_{e}}}{{{g}_{p}}}=\frac{{{M}_{e}}}{R_{e}^{2}}\times \frac{R_{p}^{2}}{R_{e}^{2}}=\frac{{{M}_{e}}}{\frac{1}{2}{{M}_{e}}}\times \frac{{{\left( \frac{1}{2}{{R}_{e}} \right)}^{2}}}{{{({{R}_{e}})}^{2}}}=\frac{7}{4}\] So,          \[{{g}_{p}}={{g}_{e}}\times \frac{7}{4}\] Hence, weight of object on planet will be \[=\frac{4}{7}\times \]weight on earth \[=\frac{4}{7}\times 700=400\,N\]


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