Results are out! Find what you Get quick advice or join the chat
Hey! Sign in to get help with your study questionsNew here? Join for free to post

Cambridge Physics Problem 20: Thermal System Problem

Announcements Posted on
Talking about ISA/EMPA specifics is against our guidelines - read more here 05-03-2015
  1. Offline

    Two cylinders A and C of equal volume V contain the same ideal gas at temperature T and at pressures 2p and p respectively. A valve connecting the two cylinders is opened slightly and as the gas leaks from A to B, the pressure in A is maintained at 2p by pushing in a piston. The process is continued until the gas in cylinder B is also at 2p. If there is good thermal contact between the cylinders but the are thermally insulated from their surroundings, find:
    (i) The final temperature in terms of T
    (ii) the final volume of gas in cylinder A in terms of V.

    Before I attempt the question, may I ask if the final temperature will be the same for both sides of the cylinder? What about the pressure? I'm still visualising the problem. What other tips can you give me? Thank you!
  2. Offline

    Yes good "thermal contact" should mean that the cylinders reach thermal equilibrium rapidly, the pressure in A is kept constant while the pressure in B increases as the moles of gas there increases.

    Tips: this is kinda dependent on my answer being right but it seems reasonable :P , anyway...


    Set up an equation of state for cylinder B, then one for the system at equilibrium when the pressure is the same in both cylinders I treated the system as one cylinder : if you were to just weld the cylinders together there would be no movement of gas because the pressure is the same in both)

    Then consider the work done on the system : You have compressed the system by a certain volume against a constant pressure of 2P, the work done is the increase in internal energy of the gas (which for a monoatomic gas should = 3/2 nRT), from the surroundings as the cylinders are thermally insulated
  3. Offline

    Any other comments from anyone?
  4. Offline


    I'm having trouble eliminating the VA' and VB' . Can anyone help me on this?

    Is molar heat capacity necessary to solve the question?


Submit reply


Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. By joining you agree to our Ts and Cs, privacy policy and site rules

  2. Slide to join now Processing…

Updated: July 3, 2012
2015 general election
New on TSR

Loved by Students

Our big survey results unveiled

Article updates
Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.