Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional force are 10% of the input energy. How much power is generated by the turbine ? (g=10 m/s2) ( NEET Exam 2021-Physics Section)

(1) 10.2 kW

(2) 8.1 kW

(3) 12.3 kW

(4) 7.0 kW

Solution: (2)

In the above question, height is given as 60 metres.

mass per unit time= 15 kg/s

g= 10m/s²

^{Loss due to frictional force is given as 10% of energy i.e. only 90% input is used to generate energy.}

^{P= mgh/t*0.9}

P=10 x 60 x 15 x 0.9 = 8.1 kW

Hence, option (2) is correct.

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