1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: U-shaped tube fluid dynamics

  1. May 11, 2016 #1
    1. The problem statement, all variables and given/known data
    Suppose we have a u-shaped tube filled with water, with oil added at one end which disturbs the equilibrium. Now say one end is blocked off and the other is exposed to air flow which reduces the pressure above the water and causes the water to climb back to equilibrium with the top of the oil. What would be the velocity of the wind above the open end?

    2. Relevant equations

    3. The attempt at a solution
    If the column of oil has a length 'L', then the pressures at the bottom level of the oil are the same:

    P1watergL = PairoilgL
    P1 = Pair + gL(ρoilwater) (1)

    Where P1 is the pressure due to the air flow
    Using Bernoulli's equation at the top of the tube as the reference point yields:

    P1+0.5ρairvair2 = Pair (2)

    Substituting equation (1) into (2) gives


    And then the velocity of air can be found... Is my work good? Thanks!
  2. jcsd
  3. May 16, 2016 #2
    What does P(air) exactly stand for?
  4. May 16, 2016 #3

    rude man

    User Avatar
    Homework Helper
    Gold Member

    I would think we'd have to know the size of the column of oil ...

    ... and the density of the oil while you're at it ...
  5. May 17, 2016 #4
    The air pressure
  6. May 17, 2016 #5
    It has length 'L' and density ρoil

    I'm not asking for a specific solution, just wanted to see if my work checks out.
  7. May 18, 2016 #6
    Can you please provide a diagram?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted