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Homework Help: Internal Enery, heat and work/HELP

  1. Mar 4, 2010 #1
    1. The problem statement, all variables and given/known data
    There's .1 mole of an ideal gas trapped in a cylinder with a movable piston.
    If Pi= Pf= 5000Pa, Vi= .04 m^3, Vf= .08m^3, Q=500J,,,Find W, change in (U), Ti and Tf.

    2. Relevant equations

    change in U = Q+W
    W= -p change in V

    3. The attempt at a solution

    W= 200J
    change in U = 700J
    Tf= i don't know how to get Ti and Tf... I am not sure whether 200J and 700J are right either..
    PLease help me!!
    Thank you!
  2. jcsd
  3. Mar 5, 2010 #2


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    Homework Helper

    You certainly know an equation connecting P, V and T for an ideal gas.

    The gas expands, is the work done on the gas positive or negative? Will this work increase or decrase the internal energy?

  4. Mar 5, 2010 #3

    Could you please explain more in detail? I don't get what you're saying:(

  5. Mar 5, 2010 #4


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    Homework Helper

    You know P, V, n for both states of the gas, don't you? Can you calculate the temperatures?

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