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Bubble pressure

  1. Aug 29, 2016 #1
    1. The problem statement, all variables and given/known data
    What's the gauge pressure inside a droplet of water mist of diameter 0.1 mm (radius 0.05 mm), assuming that the droplet is spherical? Use a water-air surface tension of 0.07 Jm\(^{-2}\) and specify your answer in bar /atmospheres (where 1 atmosphere pressure is \(1 \times 10^5\) Pa.
    2. Relevant equations
    delta P= 2*0.07/r (in meters)

    3. The attempt at a solution
    I subed the value inside the equation and i got 3000pa.. which is 3atm? am i right?
     
  2. jcsd
  3. Aug 29, 2016 #2

    gneill

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    Staff: Mentor

    It looks like you've chosen the correct formula to use, and your result in Pascals looks good to me for one significant figure of accuracy. Note however that an atm is not 1000 Pa; One atm is to be taken as 105 or 100,000 Pa according to the definition you're given in the problem statement.
     
  4. Aug 29, 2016 #3
    so 0.03?
     
  5. Aug 29, 2016 #4

    gneill

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    Staff: Mentor

    Yes, that looks like a good value. Be sure to always specify units on any values that you present!
     
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