Frostbite Theater

Announcer: Frostbite Theater presents... Cold Cuts! No baloney!

Joanna and Steve: Just science!

Joanna: Hi! I'm Joanna!

Steve: And I'm Steve!

Joanna: Here's a trick that you've probably seen before.

Pour some water into a jar. Take a card and place it over the opening. Flip the jar over and let go of the card. The card stays put and the water doesn't come out!

Steve: So, why does this happen?

There are a number of factors involved, but it's mainly due to a combination of air pressure and surface tension. When we let go of the card, everything starts to fall. That reduces the air pressure inside the jar. The pressure difference between the inside of the jar and the outside of the jar supports the weight of the water. The surface tension also creates a seal between the jar and the card and, since the air can't get in, water can't get out.

Joanna: And... if you remove the card just right...

...the surface tension maintains the seal and the water stays put!

But, you have to keep the jar perfectly level. If you tilt it too much, the symmetry is broken and the water comes out.

However, if you're good enough,

Water: Splash!

Steve: Whoa!

Joanna: ...you can recover!

Steve: That is so cool!

Water: Splash!

Joanna: Ahhh, so close!

Steve: What did I do wrong?

Joanna: Thanks for watching! I hope you'll join us again soon for another experiment!

I think you didn't hold it perfectly level.

Steve: Okay... Try it again.

Perfectly level...

Water: Splash!

Steve: Aaarrgg, man!

Joanna: So close...

Steve: One more time...

Water: Splash!