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Thermodynamics Pressure Problem Help

  1. Feb 4, 2013 #1
    1. The problem statement, all variables and given/known data

    The ice cap on the North Pole could be 1000 m thick with a density of 920 kg/m3. Find the pressure at the bottom and the corresponding melting temperature.


    2. Relevant equations

    Steam tables
    ΔP = ρgH

    3. The attempt at a solution

    ΔP = (920 kg/m3)*(9.28 m/s2)*(1000) = 9022 kPa
    P = Pinitial + 9022 kPa

    I have no idea how to find initial pressure, which I think is my main information missing, then from there I would need to find the corresponding temperature.
     
  2. jcsd
  3. Feb 4, 2013 #2

    Redbelly98

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    Welcome to Physics Forums.

    The initial pressure is the pressure at the top of the ice cap ... which is the pressure pretty much anywhere on the surface of Earth. :wink:

    EDIT added:
    You're a tad slow today, SteamKing! :smile:
     
  4. Feb 4, 2013 #3

    SteamKing

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    What's on top of the polar ice cap? That's how you find the initial pressure.

    Hint: it blows past you in the breeze.
     
  5. Feb 4, 2013 #4
    Alright, so the pressure at the surface is 1 atm = 101.325 kPa, which gives me:

    P = Po + ΔP = 101.325 + 9022 = 9123 kPa

    From here, finding temperature would be found by maybe a P-T chart, where the substance goes from solid -> liquid? Around 275 K is what I get.
     
  6. Feb 5, 2013 #5

    Redbelly98

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    Looks good.
    Yes, that should work.
    That's not a terrible approximation, though it is possible they are looking for a more accurate value. I'm not saying they are, just saying it's a possibility.

    For a more accurate value, think about how does the 9000 kPa temperature on the chart compare to the temperature at 101 kPa?

    p.s to SteamKing: I think this is getting more into your territory than mine. :smile:
     
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