1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

[Thermodynamics] Is this even possible?

  1. Feb 5, 2014 #1
    I'm not asking about the specific questions contained in the attached document - I know all the answers. I'm wondering if this is even possible.

    A to B: free expansion (which I take always means "adiabatic free expansion").

    B to C: adiabatic compression.

    Adiabatic means no heat is exchanged. So if system is returned to its original volume adiabatically, and no heat is exchanged, what -- physically -- could account for an increased pressure at C??

    Attached Files:

  2. jcsd
  3. Feb 5, 2014 #2


    User Avatar
    Science Advisor

    During the free expansion, no work is done by the gas and no heat is exchanged, so the internal energy of the gas is unchanged. During the adiabatic compression, however, while it is true that no heat is exchanged, work is done on the gas by the piston doing the compression. So the internal energy of the gas is increased.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook