What fraction of the air molecules

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Homework Help Overview

The discussion revolves around a problem related to thermodynamics, specifically concerning the fraction of air molecules that must be expelled from a house as the temperature increases from 17.0° C to 28.0° C, while maintaining constant pressure.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the calculation of the fraction of air molecules remaining versus those pushed outside, with some questioning the interpretation of the problem and the correct method to find the fraction.

Discussion Status

There is ongoing exploration of the problem with participants providing different interpretations of the fraction calculation. Some guidance has been offered regarding potential misunderstandings in the approach to the problem, but no consensus has been reached on the correct answer format or reasoning.

Contextual Notes

Participants note confusion regarding the answer format and significant figures, as well as the possibility of different interpretations of the fraction calculation leading to varying results.

lalahelp
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Homework Statement


What fraction of the air molecules in a house must be pushed outside while the furnace raises the inside temperature from 17.0° C to 28.0° C? The pressure does not change since the house is not 100% airtight.

Homework Equations


v2/v1=17+273/28+273
=.963


Why is my answer wrong
 
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You've calculated the fraction that's left inside rather than the fraction that was pushed outside.
 
is it .037?
 
lalahelp said:
is it .037?

Is that a guess or do you have a reason to back up that number?
 
its supposed to says 3.7 percent... I subtracted the 96.3 from 100
 
lalahelp said:
its supposed to says 3.7 percent... I subtracted the 96.3 from 100

Then that's okay. Looks good.
 
I put the answer but for some reason its still saying its incorrect?
 
lalahelp said:
I put the answer but for some reason its still saying its incorrect?

Is there a particular answer format that the question requires? Is it finicky about significant digits?
 
No and No... I am not sure why its doing this.
 
  • #10
lalahelp said:
No and No... I am not sure why its doing this.

:confused: I don't know what else to suggest. I can't think of any other reasonable interpretation of 'fraction of the air molecules' that would lead to a different result.
 
  • #11
yeh, Thank you for your help, I am going to email my proffessor about the question
 
  • #12
Another Homework Helper* has suggested that it is perhaps possible that the question is looking for (n28C-n17C)/n28C ("what fraction of the gas was pushed out") instead of (n28C-n17C)/n17C ("what fraction of the gas will be pushed out"). It would make a small but noticeable difference in the result.


* Thanks D H!
 
  • #13
Yes! that was correct Thank you D H!
 

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