Work in Isothermal, Isobaric and Adiabatic Processes · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Each process has its own work rule

Science · Thermal & Statistical Physics · ages 19-20
Name ______________________   Date ____________

  1. Adiabatic means no heat enters or leaves the gas.

    Circle one:   True   False

  2. What is the work of an isobaric expansion?

    • p times delta V
    • n R T log V2 over V1
    • Zero in all cases

  3. What is gamma in the adiabatic relation?

    • R over n
    • Cp over Cv
    • T over p

  4. On a pV plot, how does the adiabat compare with the isotherm?

    • Flatter, since heat escapes
    • Identical, since both use pV
    • Steeper, since gamma tops one

  5. Isobaric expansion at 2e5 Pa with delta V of 0.01 cubic m. Give the work in J.

    Answer: ______________

  6. Why does an adiabatic compression raise the temperature?

    • Heat flows in from the walls
    • Work done on the gas stays inside it
    • Molecules leave the container

  7. A gas expands freely into a vacuum, so Q is 0 and W is 0. Give the internal energy change in J.

    Answer: ______________

  8. An isothermal compression raises the gas temperature.

    Circle one:   True   False

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Answer key

For grown-ups. Fold this page away before handing over the rest.

Each process has its own work rule W1-mt_WzVxwN3svc-s1

  1. True · Q equals zero defines the adiabatic process.
  2. p times delta V · Constant pressure factors out of the integral.
  3. Cp over Cv · Gamma is the ratio of the two molar heat capacities.
  4. Steeper, since gamma tops one · Gamma above one tilts the adiabat steeper.
  5. 2000 · Multiply 2e5 by 0.01 to get 2000.
  6. Work done on the gas stays inside it · With Q zero, compression work becomes internal energy.
  7. 0 · First law gives delta E as Q minus W, which is zero.
  8. False · Isothermal holds T fixed while heat flows out.
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