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Understanding gases

  1. Feb 2, 2012 #1
    50 minutes into this video the professor puts a balloon into liquid nitrogen that's about 1/4 of the room temperature, but its volume decreases to much less than 1/4 of its original volume. Why?

    Right after the balloon demo, he talks about tennis balls. Why if you open up a can of tennis balls, don't play with them for a few days, do they become useless? And how does this relate to whether the pressure in the sealed can of tennis balls was less than or greater that 1 atm?
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Feb 3, 2012 #2
    I figured out the bolded! It's because a large percentage of the air in the balloon condenses at such a low temperature.

    I still have no idea about the 2nd question though. Please watch the video starting at the 51:30 mark to hear it.
    Last edited by a moderator: Sep 25, 2014
  4. Feb 3, 2012 #3
  5. Feb 3, 2012 #4
    Thanks James. I now understand all the puzzles that are given at the end of the 1st semester MIT physics lectures. I highly recommend the lectures to other beginners.
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