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Flow of water?

  1. Dec 30, 2004 #1
    Maybe this should be in the math section, I'm not sure. I have this friend that works in the water industry that tells me my town runs off of 3 wells that each have the pressure to shoot a stream of water 8" diameter 12.6m up. I was wondering from this information how I could figure out how fast that water must be moving and in turn the volume. So how could I go about doing this?
  2. jcsd
  3. Jan 1, 2005 #2

  4. Jan 1, 2005 #3
    You can use energy conservation to solve that.
    Take the potential energy as 0 at the output of the well.

    The energy of the stream at the output of the well is

    [tex]\frac{Mv^2}{2}[/tex] ​

    (no potential energy, only kinetic energy, speed is v, M is the mass of a piece of water)

    The energy of the stream at the highest reach, when the velocity drops to zero is:

    [tex]Mg[/tex] ​

    (no kinetic energy, only potential energy)

    Since energy is conserved during the motion (without air friction), we have:

    [tex]\frac{Mv^2}{2}=Mgh[/tex] ​
    (h is the highest reach)

    We get easily:

    [tex]\frac{v^2}{2}=gh[/tex] ​
    [tex]v={(2gh)}^{1/2}[/tex] ​

    Finally, this gives v = 15.7 m/s .
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