Thermodynamics Pressure Problem Help

AI Thread Summary
To determine the pressure at the bottom of a 1000 m thick ice cap with a density of 920 kg/m3, the pressure difference is calculated using ΔP = ρgH, resulting in 9022 kPa. The initial pressure at the surface is approximately 101.325 kPa, leading to a total pressure of 9123 kPa at the bottom. To find the corresponding melting temperature, a pressure-temperature chart can be utilized, estimating the temperature around 275 K. Accuracy may vary depending on the specific conditions and assumptions made. The discussion emphasizes the importance of understanding initial pressure and its impact on calculations.
MechE2015
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Homework Statement



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.

Homework Equations



Steam tables
ΔP = ρgH

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.
 
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MechE2015 said:

Homework Statement



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.

Homework Equations



Steam tables
ΔP = ρgH

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.
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:
 
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.
 
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.
 
MechE2015 said:
Alright, so the pressure at the surface is 1 atm = 101.325 kPa, which gives me:

P = Po + ΔP = 101.325 + 9022 = 9123 kPa
Looks good.
From here, finding temperature would be found by maybe a P-T chart, where the substance goes from solid -> liquid?
Yes, that should work.
Around 275 K is what I get.
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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