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Homework Help: Water and Mercury Pressure

  1. Aug 14, 2008 #1
    1. The problem statement, all variables and given/known data
    If you have two containers one with water (filled to 10cm) and one with mercury (5cm), how do the pressure of water and mercury compare?

    p of water = 1 gm/cm^3
    p of mercury = 14 gm/cm^3

    2. Relevant equations

    P = pgh where p is density, and h is height

    3. The attempt at a solution

    P water = (1)(10) = 10 (I am not include gravity since its the same for both and they are only looking for a ratio)

    P mercury = (14)(5) = 70

    Would the correct answer be: 7*Pwater = Pmercury ?
    Last edited: Aug 14, 2008
  2. jcsd
  3. Aug 14, 2008 #2


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    Science Advisor
    Homework Helper

    Correct, although if they were looking for the RATIO of total pressure at the bottom of the two containers then you do have to consider the air pressure.
    70 / 10 is not quite the same as 70+atm / 10+atm (ps. 1 atm is roughly 1000g/cm^2)
    The DIFFERENCE between the pressures doesn't depend on the atmosphere.
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