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

  • question_answer
    A does \[500\,\,J\] of work in \[10\] minutes and \[B\] does \[600\,\,J\] of work in \[20\] minutes. The power delivered by \[A\] and \[B\] is \[{{P}_{1}}\] and \[{{P}_{2}}\] respectively. Find the relation between\[{{P}_{1}}\]and\[{{P}_{2}}\].

    A) \[{{P}_{1}}={{P}_{2}}\]

    B) \[{{P}_{1}}>{{P}_{2}}\]  

    C) \[{{P}_{1}}<{{P}_{2}}\]

    D) \[{{P}_{1}}\]and\[{{P}_{2}}\]are undefined

    Correct Answer: B

    Solution :

    \[{{P}_{1}}=\frac{{{W}_{1}}}{{{t}_{1}}}=\frac{500}{10\times 60}=\frac{5}{6}watt=0.83\,\,watt\]     \[{{P}_{2}}=\frac{{{W}_{2}}}{{{t}_{2}}}=\frac{600}{20\times 60}=\frac{1}{2}watt=0.5\,\,watt\] Hence,\[{{P}_{1}}>{{P}_{2}}\]


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