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Isothermal expansion !

  1. Oct 12, 2005 #1
    ok i really dont understand this question, especially about finding the functions for the recompressed isothermal and about the recompression stuff, im just stuck

    An ideal monatomic gas is expanded from initial volume V1 = 1 litre, P1 = 2atm, and T1 = 300K to a volume V2 = 2 litres, and P2 = 1atm. The expansion is performed along a straight line in the PV-diagram. It is then re-compressed isothermally to its original values. a) find the function P(V) describing the expansion b) find the function T(V) during the expansion c) at which volume is the temperature a maximum Tmax and what is the volume Vm at this maximium temperature Tmax? d) what is the work done, the change in internal energy and the heat taken in during the temperature increase T to Tmax? e) what are these values for the final part of the expansion Vm to V2? f) fint the efficiency

    for the parts about work done and internal energy i think i know how to do those, by using formulas like dU=nCvdT, im just not sure

    also does this question have anything to do with adiabatic processes? i dont think it does...but correct me if im wrong, thanks!
  2. jcsd
  3. Oct 12, 2005 #2


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    What parts of this problem have you attempted ? Please show your work first.

    No, this question has nothing to do with adiabatic processes (but that should be for you to figure out).
  4. Oct 13, 2005 #3
    k for part a i used p1, v1, v2, and p1, to find the slope which is rise/run and the slope is -1, i then plugged this into y=mx+b substituting p1 as y and v1 as x, and found b to be 3, so the equation i got is P(V) = -V + 3, which i dont know if its right or not..part b i have no idea how to do because i dont have T2 given so i cant find slope and do wht i did in part a, part c i tried to use pv=nrt and isolate T but im stuck because i dont know the V at Tmax, and i dont know Tmax so i have 2 unkowns..and i think i could do parts d,e and f if i figure the rest out
    Last edited: Oct 14, 2005
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