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Air entering evacuated bottle

  1. Apr 5, 2012 #1
    When air enters into an evacuated bottle from atmosphere when the cork is opened, is there any work done by the air? My textbook says that there is , but i thought no work was done during free expansion?
    Consider the amount of air entering as the system.
    Moreover, is W=∫PdV applicable only for quasi eqbm process or all processes?
     
  2. jcsd
  3. Apr 6, 2012 #2

    haruspex

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    Some work is done in accelerating the air and in overcoming drag in the neck of the bottle. But whether that's what the textbook author had in mind I've no idea.
     
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