NS FL2 C/P Q5

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Amber9
Posts: 29
Joined: Thu Jul 04, 2019 11:08 am

NS FL2 C/P Q5

Post by Amber9 » Fri Jul 12, 2019 6:55 pm

Hi,

I'm not sure if I am understanding this: from the previous question (Q4) I gathered that the pressure and depth are in an exponential relationship because the density is not constant. Using this I can eliminate A in Q5, not sure how we can figure out if it is more or less mass of H2O per unity volume using the following statement from the question: "decreasing temperature at high altitude does change the % of air that is composed of H2O"

Thanks!
NS_Tutor_Mathias
Posts: 281
Joined: Sat Mar 30, 2019 8:39 pm

Re: NS FL2 C/P Q5

Post by NS_Tutor_Mathias » Sat Jul 13, 2019 6:29 pm

Nothing about Q4 really gives you any direct insight into Q5. You are correct however that pressure and height have an exponential relationship - namely exponential decay, trending to virtually 0 atm in space. Good!

The key to understanding Q5 is remembering that relative humidity is a measure of how much moisture is in the air compared to the maximum it could hold. The question stem tells us that the maximum it can hold goes down, but that we are to assume that the relative humidity stays the same. Let's say the relative humidity is 50% - so 50% of what the air can hold at sea level is more than 50% of what the air can hold at 3000 m, so there we go: There is less mass of H2O in the air at 3000 m for any given volume.
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