Work Energy And Power Question 198
Question: An engine pumps up 100 kg of water through a height of 10 m in 5 s. Given that the efficiency of the engine is 60% . If $ g=10m{s^{-2}} $ , the power of the engine is [DPMT 2004]
Options:
A) $ 3.3kW $
B) $ 0.33kW $
C) $ 0.033kW $
D) $ 33kW $
Show Answer
Answer:
Correct Answer: A
Solution:
Work output of engine = mgh = $ 100\times 10\times 10=10^{4}J $
Efficiency (h) = $ \frac{output}{input} $
Input energy = $ \frac{outupt}{\eta } $
$ =\frac{10^{4}}{60}\times 100=\frac{10^{5}}{6}J $
Power = $ \frac{\text{input energy}}{time} $ = $ \frac{10^{5}/6}{5}=\frac{10^{5}}{30}=3.3\ kW $
