An engine pumps water through a hose pipe. water passes through the pipe & 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?

The water from the hose pipe comes out at the speed, v = 2 m/s

Mass per unit length of the pipe = 100 kg/m

So, amount of water that comes out per second = 100 × 2 = 200 kg (since, the water covers 2 m per second and there is 100 kg water per meter)

Therefore, Kinetic energy of the water coming out per second is KE = ½ × 200 × 2^{2} = 400 J

This is also the work done by the pump per second. So, the power of the pump is, P = 400/1 = 400 W

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