Need Help Solving for Work Done: 60,000 J

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Homework Help Overview

The discussion revolves around calculating the work done during a thermodynamic process involving gas compression and expansion, with a specific focus on achieving a total work value of 60,000 J as indicated in a textbook. The subject area includes concepts from thermodynamics and gas laws.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss various calculations for work done during different segments of the process, questioning the use of pressure values and unit conversions. There is a focus on whether average pressure should be used and the appropriateness of conversion factors.

Discussion Status

Participants are actively engaging with the problem, offering insights and corrections regarding pressure values and unit conversions. Some have noted that adjusting the pressure used in calculations brings them closer to the expected answer, indicating a productive exploration of the problem.

Contextual Notes

There are mentions of potential assumptions regarding pressure values and unit conversions, as well as the need for clarity on the units used in calculations. The original poster expresses uncertainty about their calculations and seeks confirmation on their approach.

JFS321
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All, I need some direction on the following question, please.
Correct answer is 60,000 J according to book.

Here's what I have so far, but it may be incorrect: Work done C-->D is (2 atm)(-400 L)(101) = -81,000 J, so work was done on the system when the gas was compressed. No work is done D-->A. Lastly, work done A-->C is (3 atm)(400 L)(101) = 121,200 J. This is work done by the gas on the surroundings. As you can see, my figures do not get to 60,000 J! Thanks in advance. Hopefully I haven't done anything too stupidly obvious!
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For A-->C, why did you use 3atm? Shouldn't it be the average pressure?
 
units for pressure should be Pa and units for volume should be m3
 
The conversion was handled with the (101) term.
1 L-atm = 101.325 J
Perhaps the problem assumes a simpler conversion factor of approx. 1:100.
 
Yes, it should be 3.5 atm and this gets me very close to the 60,000 J answer. Thank you.
 
RUber said:
The conversion was handled with the (101) term.
1 L-atm = 101.325 J
Perhaps the problem assumes a simpler conversion factor of approx. 1:100.
RUber said:
The conversion was handled with the (101) term.
1 L-atm = 101.325 J
Perhaps the problem assumes a simpler conversion factor of approx. 1:100.

sorry...I see that the units were taken care of 103 x 10-3
 

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