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Homework Help: Compression of a gas

  1. May 22, 2017 #1
    1. The problem statement, all variables and given/known data

    A closed cylinder with a piston is used to compress gas that is initially at 1bar and temperature 293K. The compression is performed adiabatically until the volume is 1m3 and the pressure is 10bar, calculate the work done.

    2. Relevant equations

    pV = nR0T - ideal gas assumption
    pVy = const. - adiabatic compression
    W = (p2V2 - p1V1) / y - 1 - work for adiabatic compression

    3. The attempt at a solution

    We have the following unknown variables: T2 , V1 and y. And we only have two equations. Is there anything I am missing?
  2. jcsd
  3. May 22, 2017 #2
    Do you know what gas is, or whether it is mono atomic?
  4. May 22, 2017 #3


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    2017 Award

    Hello BassGuitar, :welcome:

    Can't you use the ideal gas equation twice ?

    [edit] :smile: never mind. Leave this to Chet !
  5. May 22, 2017 #4
    Unfortunately, the gas type is not mentioned :(
  6. May 22, 2017 #5
    Well, you need to know the heat capacity, or equivalently, ##\gamma##. Suppose you assume that the gas is air, with ##\gamma=1.4##
  7. May 23, 2017 #6
    Yes, so I guess the problem is under-defined. If I assume that the gas is air the solution is obvious. Thank you for your help. I will mark this as solved.
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