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: Internal energy change

  1. Jun 15, 2006 #1
    I need a little starter on this one....can't figure out how to do it(or even start it)....I'll work it, if I can get some help along the way....

    Two moles of an ideal gas at 20 deg C undergo a free adiabatic expansion from 2.0 liters to 66 liters. Then the gas is adiabatically compressed such that the pressure is inversely proportional to the square of the volume: P=P(not)(V(not)/V)^2. What is the total internal energy change after both processes if the last compression reduces the volume by a factor of 4.

    The problem is kinda hard to understand in itself for me....so any help would be greatly appreciated.

  2. jcsd
  3. Jun 15, 2006 #2
    anyone else understand this problem enough to help me along??
  4. Jun 15, 2006 #3

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    What is the relationship between Pressure and Volume in an adiabatic compression or expansion? (Hint: it depends on CP/CV for the gas. How do you determine [itex]\gamma[/itex] for this particular gas?)

    What is the expression for the internal energy of a gas? (what property does it depend on?) Can you determine that property from the information provided?

    Last edited: Jun 15, 2006
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook