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9th Class Science Gravitation and Floatation Question Bank Gravitation Summative Objective Problems

  • question_answer
    Assuming earth to be a sphere of uniform mass density, how much would a body weigh half down the centre of the earth, if it weighed 100 N on the surface.

    A)  50 N     

    B)  100 N     

    C)  25 N                     

    D)  200 N

    Correct Answer: A

    Solution :

      \[{{g}_{d}}=g(1-d/R)=g\left( 1-\frac{1}{2} \right)=\frac{g}{2}\] \[\therefore \,\frac{{{w}_{s}}}{{{w}_{s}}}=\frac{mg}{m\frac{g}{2}}\Rightarrow {{w}_{d}}=\frac{{{w}_{s}}}{2}=\frac{100N}{2}=50N\]      


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