Q. 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 m/s²)
A) 7.0 kW
B) 8.1 kW
C) 10.2 kW
D) 12.3 kW
Explanation
[Solution from source] Input power = (dm/dt)gh = 15 × 10 × 60 = 9000 W. With 10% lost, the output is 0.9 × 9000 = 8100 W = 8.1 kW. 9 kW without the loss is not offered; adding the loss instead of subtracting it would give about 9.9 kW. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.