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Homework Help: Calculating the time

  1. Oct 3, 2008 #1
    A airliner cabin with 30000 cuft containing 10000 ppm of x is to be flushed with fresh air until the concentration is 100ppm of x. The flow rate is 600ft^3/min. How many minutes till the concentration is at 100ppm. Could somebody help me or guide me in solving this problem.
  2. jcsd
  3. Oct 3, 2008 #2


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    Hi juice34! :smile:

    You can assume that the flow rate in equals the flow rate out.

    Hint: call the amount of x "p".

    Then the flow in contains [how much?] of x/min (doesn't depend on p), and the flow out contains [how much?] of x/min (does depend on p) … make a differential equation for p and t. :smile:
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