An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of \[2\,\text{m}{{\text{s}}^{-1}}.\]The mass per unit length of water in the pipe is \[100\,\text{kg}{{\text{m}}^{-1}}.\] What is the power of the engine?
A) 400W
B) 200W
C) 100 W
D) 800 W
Correct Answer:
D
Solution :
Power \[=\mu {{v}^{3}}=\frac{m}{l}\times {{v}^{3}}\] \[=100\times {{(2)}^{3}}=800\,W\]