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9th Class Science Work and energy Question Bank Work Power and Energy Summative Objective Problems

  • question_answer
    A body of mass 1 kg is projected vertically up with certain velocity. At certain point its P.E and K.E are 8J and 90J. Then maximum height reached by it is(\[\text{g}=\text{9}.\text{8 m}/{{\text{s}}^{\text{2}}}\])

    A)  1 m                       

    B)  10 m

    C)  0.1 m                   

    D)  100 m

    Correct Answer: B

    Solution :

      \[m=1\,\,kg,g=9.8\,m/{{s}^{2}}\] Total energy of the body\[=8J+90\,J=98J\] At the maximum height, the body possesses only P.E \[\Rightarrow mgh=98\,\,\Rightarrow h=\frac{98}{mg}=\frac{98}{1\times 9.8}=10\,m\] \[P.E.=mgh,\,\,K.E.=1/2\,m{{v}^{2}}\]


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