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Homework Help: Pressure of a bubble in Liquid

  1. Apr 3, 2007 #1
    1. The problem statement, all variables and given/known data

    Air is trapped above liquid ethyl alcohol in a rigid container. If the air pressure above the liquid is 1.1 atm, determine the pressure inside a bubble 4.0 m below the surface of the liquid.

    2. Relevant equations

    P= P(nought) + (density)(gravity)(height)
    density of alcohol .806 x 10^3

    3. The attempt at a solution

    Pnought would be the 1.1 atm
    P= 1.1 + (806 kg/m^3)(9.8 m/s^2)(4 m)
    = 31596

    That isn't the right answer, so I'm very confused. Do I need to change atmospheres to kPas? Is that density correct? Am i even using the right equation?
    Last edited: Apr 4, 2007
  2. jcsd
  3. Apr 3, 2007 #2


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    Homework Helper

    I would definitely convert the 1.1 atm to Pa to see if that's your problem. Your units aren't consistent the way they are.
  4. Apr 3, 2007 #3
    It isnt [tex]P_0*\rho gh[/tex]
    Its [tex]P_0 + \rho gh[/tex]
  5. Apr 4, 2007 #4


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    Homework Helper

    You've got two versions of the equation written down here. The one you used in your calculation is the right one, but I can't figure out how you got the 338.22 even if it is wrong.
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