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Homework Help: Cyclic proces, confused

  1. Apr 21, 2008 #1
    1. The problem statement, all variables and given/known data

    A Cyclic proces of three parts for a monoatomic idealgas:

    1-2:
    Isochor, where:
    p2 = 2*p1
    v2 = v1

    2-3:
    Adiabatic, from v2 = v3, where:
    v3 > v2
    p3 = p1

    3-1:
    unknow proces, where
    v4 = v1
    p4 = p1

    My problem is to determine
    Q1, Q2, Q3 and W1, W2, W3 and dU1, dU2, dU3

    I can't find U3, W3

    2. Relevant equations
    dU1 + dU2 + dU3 = 0

    W1 = 0, dU = Q (isochor)
    Q2 = 0, dU = -W (adiabatic)

    3. The attempt at a solution
    I'm really lost on the part finding Q3, W3
    :(
     
  2. jcsd
  3. Apr 21, 2008 #2

    Hootenanny

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    Have you determined dU1 and dU2?
     
  4. Apr 21, 2008 #3
    yes i have
     
  5. Apr 21, 2008 #4

    Hootenanny

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    And is the data plotted on a PV curve?
     
  6. Apr 21, 2008 #5
    Nope, i don't have that information.
     
  7. Apr 21, 2008 #6

    Hootenanny

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    Shouldn't these two values be v3 and p3?
     
  8. Apr 21, 2008 #7
    my point is just that after v3 and p3, you go back to the initial place v1 and p1.
    Thats what i mean by 3-1.
     
  9. Apr 21, 2008 #8

    Hootenanny

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    Yes but note that p3 = p1, therefore this third 'unknown process' (3-1) is isobaric.
     
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