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Homework Help: Simple U-Tube question

  1. Sep 16, 2008 #1
    1. The problem statement, all variables and given/known data
    A U-tube manometer contains a fluid with density of 825 kg/m^3. The difference in height of the two columns is 35cm. What is the pressure difference?

    2. Relevant equations

    3. The attempt at a solution
    I have no bloody clue. I'm sure I've done this before in AP Chem, but right now... I'm clueless. I think its something really simple, too.
    Edit: Now that I think of it... the time variable in P=m/(A*t^2) doesn't change (there is no delta t), so density of the liquid multiplied by the difference in height squared would give me the difference in pressure. Am I even close to the truth?
    Last edited: Sep 16, 2008
  2. jcsd
  3. Sep 16, 2008 #2


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    Science Advisor
    Homework Helper

    Pressure is force / area , or weight / area if you prefer.
    You don't need the area of the tube since this cancels out, but if you prefer you can think of it as 1m^2.
    Now just work out the weight of the extra 35cm * 1m^1 of fluid.
    This is the weight pressing down on 1m^2 = pressure (watch the units)
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