Water falls 60 m at a mass flow rate of 15 kg s⁻¹ through a turbine. Friction losses are 10% of input energy. Find power generated (g=10 m s⁻²).
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Question

Water falls 60 m at a mass flow rate of 15 kg s⁻¹ through a turbine. Friction losses are 10% of input energy. Find power generated (g=10 m s⁻²).

G1 Physics · Accepted Answer

Step 1 — Principle: Energy delivered over a time interval is E = Pt for constant power. Step 2 — Working: Input power ṁgh=15×10×60=9000 W. Step 3 — Working: Useful 90% output =.9×9000=8100 W=8.1 kW. Correct answer: B — 8.1 kW.