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Homework Help: (21-11) Thermodynamics problem help

  1. Dec 9, 2011 #1
    1. The problem statement, all variables and given/known data

    The volume of a gas is decreased by a constant external pressure of 0.25 atm, changing from 2.0 liters to 0.50 liters. During this compression, 75 J of energy flows out of the gas. Find the work done by the gas and its change in internal energy.



    2. Relevant equations

    First Law of Thermodynamics= ΔE=Q - W




    3. The attempt at a solution

    Is 75 J of energy the final energy

    I'm not too sure on how to find the Q or W

    I'm not too sure on how to complete this problem

    Could someone me help on how to start the problem
     
  2. jcsd
  3. Dec 9, 2011 #2

    Andrew Mason

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    Homework Helper

    I think that we are to assume that the energy flows out of the gas in the form of heat flow, Q. I think we are also supposed to assume that the work done by the gas, W = PΔV. With those assumptions you should be able to solve this. Be careful about the sign of the work.

    AM
     
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