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PV diagrams

  1. Jun 10, 2016 #1
    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!
    upload_2016-6-10_10-45-24.png
     
  2. jcsd
  3. Jun 10, 2016 #2

    RUber

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    For A-->C, why did you use 3atm? Shouldn't it be the average pressure?
     
  4. Jun 10, 2016 #3
    units for pressure should be Pa and units for volume should be m3
     
  5. Jun 10, 2016 #4

    RUber

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    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.
     
  6. Jun 10, 2016 #5
    Yes, it should be 3.5 atm and this gets me very close to the 60,000 J answer. Thank you.
     
  7. Jun 10, 2016 #6
    sorry....I see that the units were taken care of 103 x 10-3
     
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