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Homework Help: Absolute pressure with container

  1. Nov 14, 2011 #1
    1. The problem statement, all variables and given/known data

    A 1.00m tall container is filled to the brim, partway with mercury and the rest of the way with water. The container is open to the amosphere. What must be the depth of the mercury so that the absolute pressure on the bottom of the container is twice the atmospheric pressure?

    2. Relevant equations

    P2 = P1 + (rho)gh

    3. The attempt at a solution

    I know that the pressure at the bottom has to be 2*10^5 Pa, but I'm just not sure how to approach the rest of the problem. How do I deal with the split densities?
  2. jcsd
  3. Nov 15, 2011 #2


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    Both the column of mercury of height y and water of height 1.00-y contributes to the pressure of the bottom, and the contributions add up.

  4. Nov 15, 2011 #3
    Do I assume that the water is underneath the mercury? or does it not matter?
  5. Nov 15, 2011 #4
    Does this equation work?:

  6. Nov 15, 2011 #5


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    Which fluid is denser? Mercury or water?
  7. Nov 15, 2011 #6


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    It does not matter in te equation (it is correct), but mercury is much denser than water...

  8. Nov 15, 2011 #7
    Thanks everyone, I managed to solve the problem.
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