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

  • question_answer
    If the radius of the earth is 6400 km then weight of an object of mass 100 kg at height 6400 km from the surface of the earth is (g m the surface of the earth is\[\text{1}0\text{m}/{{\text{s}}^{\text{2}}}\])

    A)  250 N   

    B)  1000 N

    C)  100 N                   

    D)  2500 N

    Correct Answer: A

    Solution :

      \[{{w}_{1}}=mg,\,\,{{g}_{1}}=\frac{g{{R}^{2}}}{{{(R+h)}^{2}}}=\frac{g}{{{\left( 1+\frac{h}{R} \right)}^{2}}}\] \[=\frac{10}{{{\left( 1+\frac{6400}{6400} \right)}^{2}}}=\frac{10}{4}2.5m/s\] \[\therefore {{w}_{1}}=100\times 2.5=250N\]   


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