Question

An engine pumps up $100\, kg$ of water through a height of $10 \,m$ in $5 \,s$ . Given that, the efficiency of engine is $60\%$ If $g=10\,ms^{-2}$ the power of this engine is

• A. 3.3 kW
• B. 0.33 kW
• C. 0.033 kW
• D. 33 kW

Answer 1

Answer: (A)

3.3 kW

Answer 2

Efficiency of engine, $\eta=60 \%$ Thus, power $=\frac{\text { work / time }}{\eta}=\frac{100}{60} \times \frac{m g h}{t}$ Given, $m=100\, kg ,\, h=10 \,m , t=5 \,s$ and $g=10 \,ms ^{-2}$ Hence, power $=\frac{100}{60} \times \frac{100 \times 10 \times 10}{5}$ $=3.3 \times 10^{3} \,W$ $=3.3\, kW$