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NEET 2010 (AIPMT, Prelims) · Power

Power question from NEET 2010 (AIPMT, Prelims)

Q44NEET 2010 · AIPMT · PRELIMSMedium

Power

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?

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Answer: (a)

  1. Mass leaving per second =λv= \lambda v (λ\lambda = mass per unit length).
  2. P=12(λv)v2=12λv3P = \dfrac{1}{2}(\lambda v)v^2 = \dfrac{1}{2}\lambda v^3
  3. P=12×100×23=400 WP = \dfrac{1}{2} \times 100 \times 2^3 = 400\text{ W}
  4. So the answer is (a) 400 W.
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