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Popping bubbles underwater

  1. Jul 26, 2009 #1
    If you poke at a soap bubble floating in air it pops. Can you make an underwater air bubble pop when you poke at it? I say no, my wife thinks you can.

    What say you? And why?
  2. jcsd
  3. Jul 26, 2009 #2
    i guess you could break it into smaller bubbles, but it would not pop..the best you could do would be to break it up into so many bubbles that it appears to be dissolved, but that would depend on the temperature of the water.
  4. Jul 26, 2009 #3
    If you popped it underwater, where would the air go? And what would happen to the layer of water surrounding it?

    The answer is clearly no. You could break it into a lot of pieces, maybe, perhaps so small that you couldn't see them with the naked eye, perhaps so small that they couldn't even really be called bubbles at all, but that's not really "popping" the bubble.
  5. Jul 26, 2009 #4

    Andy Resnick

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    I think you are forgetting that a soap bubble, in air, is a thin fluid film separating two volumes of air- popping the bubble means collapsing the film.

    For an air bubble in water, there is no thin film- although you could conceivably make a thin air film separating two fluid volumes as above, and you could indeed pop that.
  6. Jul 27, 2009 #5
    Compare what you're describing to the phenomenon known as cavitation. You may not be able to initiate it by poking your slow moving bubble under water, but in a low pressure region caused by flow around a propeller screw you will often get bubble formation and collapse. This can generate significant shock effects, potentially leading to a great deal of damage.

    My answer would be yes and no - it could happen, but probably not just poking it with your finger.
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