Work Energy and Power - Result Question 39

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42. An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of $2 m / s$. The mass per unit length of water in the pipe is $100 kg / m$. What is the power of the engine?

======= ####42. An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of $2 m / s$. The mass per unit length of water in the pipe is $100 kg / m$. What is the power of the engine?

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/work-energy-and-power/work-energy-and-power—result-question-39.md (a) $400 W$

(b) $200 W$

(c) $100 W$

(d) $800 W$

[2010]

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Answer:

Correct Answer: 42. (d)

Solution:

(d) Amount of water flowing per second from the pipe

$ =\frac{m}{\text{ time }}=\frac{m}{\ell} \cdot \frac{\ell}{t}=(\frac{m}{\ell}) v $

Power $=$ K.E. of water flowing per second

$=\frac{1}{2}(\frac{m}{\ell}) v \cdot v^{2}$

$=\frac{1}{2}(\frac{m}{\ell}) v^{3}$

$=\frac{1}{2} \times 100 \times 8=400 W$