Question

Water falls from a height of 60m at the rate of 15kg.s to operate a turbine. The losses due to friction forces are 10% of energy. How much power is generated by the turbine? g=m/s^2

(a) 7kW

(b) 10.2kW

(c) 12.3kW

(d) 8.1kW

The question was posed to me in homework.

Question is from Forces of Nature in portion Gravitation of Engineering Physics I

Answer 1

Right choice is (d) 8.1kW

The explanation is: P = W/t=mgh/t=(15×10×60)/1 = 9000W = 9kW

Loss=10%

Useful power=90% of 9kW = (90×9)/100=8.1kW.