Reversible and Irreversible Expansion or Compression Work
Reversible and Irreversible Expansion or Compression Work
This Demonstration shows animations of reversible and irreversible expansions and compressions of an ideal diatomic gas in a piston-cylinder system. You can select either "compression" or "expansion" using the buttons, and you can compare two processes side-by-side (reversible isothermal, reversible adiabatic, irreversible isothermal, and irreversible adiabatic) using drop-down menus. Press the play button to watch the processes go to their final states. For an adiabatic process, the final temperature is calculated and displayed with the work. You can change the final pressure with the slider, and the pressure ranges are different for compression and expansion. As the gas volume changes for the reversible processes, more weights (blue rectangles) are added to the piston for compression or removed for expansion. For the irreversible processes, the external pressure () is constant, so the number of weights is fixed at the final value, and initially stops (red triangles) are in place to prevent the piston from moving before the play button is pressed. The animations of the reversible processes represent a continuous, smooth transition. The actual irreversible processes are faster because of the large differences in gas and external pressures. For an actual irreversible process, the piston overshoots the final volume, but this is neglected in the animations.
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