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Holding Water in glass upside down

  1. Aug 8, 2012 #1
    With the paper it can work, but without paper, I highly doubt it?
    Give me some 'physics' reason why it should/shouldn't work.

    P.S. How do I embed video? Youtube tag isn't working.
  2. jcsd
  3. Aug 8, 2012 #2
    You cam't be serious! It is a trick - magic. You want an explanation how to do the trick?
  4. Aug 8, 2012 #3
    Last edited: Aug 8, 2012
  5. Aug 9, 2012 #4
    Without the paper in place, that's got to be a trick, surely? The surface tension of the water isn't enough to hold it in place, is it? Or is it?

    Edit - I've been practicing, and run out of dry card to use, but haven't made it work so far. I'll let you know if I get a positive result!
    Last edited: Aug 9, 2012
  6. Aug 9, 2012 #5
    You are wasting your time, unless you use a glass with a very, very small diameter rim.

    The paper part is easily expalined by physics, as noted above.

    The part without the paper is the trick part. Re-run the video, but this time notice how the performer picks up the paper. He does not show you the bottom. Notice how his thumb is underneath as if to hold something else against the paper. Notice how he wiggles the paper so that the something else will neatly and snuggly fit just inside the rim so as to unseen. Turn the glass upsied down, gently remove the paper and the something else holds the water inside the glass. Same physics apply. Try a reasonably rigid clear sheet of plastic with a diameter just slightly less than the diameter of the rim. Clear is what makes it a trick, but any color will do if you are not ding a magic show.
  7. Aug 13, 2012 #6
    Good, I am glad about that. I have been experimenting with narrow glasses, including shot glasses and latterly a test tube with the name of a popular alcoholic beverage written on the side, and all have yielded negative results. I am quite pleased really that something that appeared unphysical on first viewing still appears that way on testing. Although secretly I was hoping for a positive result that would throw all my physics instincts out the window. Ah, the joys of science.
  8. Aug 13, 2012 #7
    I believed the same pressure that held the paper plus the weight of the water would be enough to hold the water alone. I was wrong. How embarrassing! I too tried this dozens of times but couldn't get it to work. As 256bits mentions, you can see him fitting something into the rim of the glass. This does work with a mesh screen though.
  9. Aug 13, 2012 #8
    I so wanted to believe it too. I suppose if it had worked it would be potentially possible to drink from the cup upside down, which would be more blatantly impossible. Still, as it stands its a great party trick. I wonder how many laptops have died this way?
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