J & K CET Medical J & K - CET Medical Solved Paper-2015

  • question_answer
    Radius of Earth is 6400 km and that of Mars is 3200 km. Mass of Mars is 0.1 that of Earths mass. Then, the acceleration due to gravity on Mars is nearly

    A)  \[1\text{ }m/{{s}^{2}}\]           

    B)  \[\text{2}\text{.5 }m/{{s}^{2}}\]

    C)  \[\text{4 }m/{{s}^{2}}\]           

    D)  \[\text{5 }m/{{s}^{2}}\]

    Correct Answer: C

    Solution :

     Acceleration due to gravity of a planet is \[g=\frac{GM}{{{R}^{2}}}\] where, M = mass of planet R = radius of planet \[{{g}_{m}}={{g}_{Mars}}=\frac{GMe}{R_{e}^{2}}\] \[\Rightarrow \] \[{{g}_{e}}={{e}_{Earth}}=\frac{GMe}{R_{e}^{2}}\] \[\frac{{{g}_{m}}}{{{g}_{e}}}=\left( \frac{Mm}{Me} \right){{\left( \frac{{{R}_{e}}}{{{R}_{m}}} \right)}^{2}}=(0.1){{\left( \frac{6400}{3200} \right)}^{2}}\] \[=(0.1){{(2)}^{2}}=4\times 10.1=0.4\] \[\Rightarrow \] \[{{g}_{m}}=(0.4)(10)=4m/{{s}^{2}}\]


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