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  • May 15, 2014, 07:09 PM
    aztect
    Question on fluids
    Hello, well I'm doing self-study at home and the text book doesn't provide solutions only answers which makes figuring out how to do these questions difficult

    First Q;
    A hose with a diameter of 2cm is connected to a sprinkler which has 2 holes on both side with a diameter if 0.19cm, the speed of the water through the hose is 0.59m/s, so what does is the velocity and speed it takes when it leaves the sprinker?

    Second Q;
    During a flood water is flushed out of a basment at 0.93m/s (velocity of the water?) the raidus of the hose is 1.2cm thus diameter is 2.4cm, the hosepasses through a 2m (the height I assume) window above the waer line so what is the power of the pump, that is pumping the water out?
  • May 16, 2014, 05:51 AM
    ebaines
    The first question is about constant mass flow - that is the rate of flow of fluid throughout the system is constant in terms of Kg/m^3. Water is considered to be virtually incompressible, so this means the volume flow of water in m^3/s is constant. You calculate this volume flow using the area of the pipe times velocity of flow. You have the two diameters and one velocity, so using constant volume flow you can determine the other velocity.

    For the second problem recall that power is equal to work done per second. What is the work needed to lift something up to a height h? W=mgh should look familiar. So power required is mass/second times g times h. Can you take it from here?

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