Holding Water in glass upside down

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In summary: 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.
  • #1
I_am_learning
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With the paper it can work, but without paper, I highly doubt it?
Give me some 'physics' reason why it should/shouldn't work.
http://www.youtube.com/watch?v=3rY0auw5wCo&feature=relmfu

P.S. How do I embed video? Youtube tag isn't working.
 
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  • #2
Give me some 'physics' reason why it should/shouldn't work.

You cam't be serious! It is a trick - magic. You want an explanation how to do the trick?
 
  • #3
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  • #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!
 
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  • #5
Rooted said:
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!

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.
 
  • #6
256bits said:
You are wasting your time, unless you use a glass with a very, very small diameter rim.

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.
 
  • #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.
 
  • #8
Jimmy said:
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.

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?
 

Related to Holding Water in glass upside down

1. What causes water to stay in a glass when held upside down?

The force of gravity is what keeps the water in the glass when held upside down. The upward pressure from the water is balanced by the downward force of gravity, creating a seal that prevents the water from spilling out.

2. How does surface tension play a role in holding water in a glass upside down?

Surface tension is the cohesive force between water molecules that creates a barrier at the surface of the water. This barrier helps to maintain the shape of the water and prevents it from spilling out of the glass when held upside down.

3. Can any type of glass hold water when held upside down?

No, not all glasses are able to hold water when held upside down. The glass must have a smooth, flat rim that can create a seal with the surface of the water. Glasses with irregular or rough edges may not be able to hold water when held upside down.

4. Is there a limit to how much water can be held in a glass when held upside down?

Yes, there is a limit to how much water can be held in a glass when held upside down. The amount of water that can be held depends on the size and shape of the glass, as well as the strength of the seal created by the surface tension and gravity. If the glass is too full or the seal is not strong enough, the water will spill out.

5. Can other liquids besides water be held in a glass when held upside down?

Yes, other liquids with similar properties to water, such as juice or milk, can also be held in a glass when held upside down. However, liquids with lower surface tension, such as alcohol, may not be able to create a strong enough seal and will spill out of the glass when held upside down.

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