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Bernoulli's equation - finding the pressure at the top of a tube

  1. Jun 4, 2004 #1
    Here's my problem:-

    A horizontal tube has a T-junction with a vertical tube coming downwards into a container of liquid, at height h below the T-junction. Air is forced into the horizontal tube which causes a pressure difference which sucks the liquid up the vertical tube.

    What is the pressure at the top of the vertical tube?

    I have the answer as
    P = Po - 1/2 * /rhoA * v^2

    P = pressure at top of vertical tube
    Po = atmospheric pressure
    /rhoA = density of air in tube
    v = velocity of air in tube

    but I can't seem to derive this equation from Bernoulli's equation. (Or anything else! :confused: )

    Any ideas?

  2. jcsd
  3. Jun 4, 2004 #2
    s'okay, I've just worked it out. It was embarassingly simple!
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