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