J & K CET Medical J & K - CET Medical Solved Paper-2014

  • question_answer
    A body weight 45 N on the surface of the earth. What is the gravitational force on it due to the earth at a height equal to half of the radius of the earth?

    A)  20 N  

    B)  45 N   

    C)  40 N   

    D)  90 N

    Correct Answer: A

    Solution :

     Acceleration due to gravity at \[h=\frac{R}{2}\] \[g=\frac{g}{{{\left( 1+\frac{h}{{{R}_{e}}} \right)}^{2}}}=\frac{g}{{{\left( 1+\frac{{{R}_{e}}}{2{{R}_{e}}} \right)}^{2}}}\] \[=\frac{g}{{{\left( \frac{3}{2} \right)}^{2}}}=\frac{4}{9}g\] \[\Rightarrow \]Sow\[=\frac{4}{9}w=\frac{4}{9}\times 45=20\,N\]


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