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9th Class Science Work and energy Question Bank Work, Energy and Power

  • question_answer
    A girl of mass \[40\,\,kg\] climbs \[50\] stairs each of average height \[20\,\,cm\] in\[50\,\,s\]. Find the power of the girl\[(g=10\,\,m\,\,{{s}^{-2}})\]

    A) \[50\,\,W\]                     

    B) \[50\times 20\,\,W\]

    C) \[80\,\,W\]           

    D)        \[50\times 20\times 2\,\,W\]

    Correct Answer: C

    Solution :

    \[W=mgh=40\times 10\times 0.2\times 50\] \[P=\frac{W}{t}=\frac{40\times 10\times 0.2\times 50}{50}=80\,\,W\]


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