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!

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

    User Avatar
    Science Advisor
    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.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook