Question

A water-pump driven by petrol raises water water at a rate of $0.5m^3/min$ from a depth of 30 m. If the pump is 70% efficient, what power is developed by the engine-

• A. 1750 W
• B. 2450 W
• C. 3500 W
• D. 7000 W

Answer 1

The correct option is C 3500 W

$\eta =\frac{Poutput}{Pinput}$
P output $=gh\frac{dm}{dt}=9.8\times 30\times \frac{0.5\times {10}^3}{60}$
P input $=\frac{9.8\times 30\times \frac{0.5\times {10}^3}{60}}{0.7}=3500W$