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

  • question_answer
                            Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional forces are 10% of energy. How much power is generated by the turbine? \[(g=10\text{ }m/{{s}^{2}})\]

    A) 12.3 kW          

    B)        7.0 kW

    C)        8.1 kW

    D)        10.2 kW                      

    Correct Answer: C

    Solution :

    Mass of water falling/second = 15 kg/s h = 60 m, \[\text{g = 10 m/}{{\text{s}}^{\text{2}}}\], loss = 10% i.e., 90% is used. Power generated \[=15\times 10\times 60\times 0.9\]                         \[\text{= 8100 W = 8}\text{.1 kW}\text{.}\]


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