This power of science demonstration is quite impressive. But it involves
the stove, so kids, get your parents help.
Before the challenge, crack open a fresh soda can so that it's just barely
open. Pour out (or drink) the soda. You now have an empty soda can. This
experiment is easier if the opening isn't wide open.
Next, take the chopstick and thread it through the pull tab. Make it
fit snuggly, so that you can easily manipulate the can.
Now prepare two pots of water, side by side on the stove. Bring one to
a full boil, and fill the other with ice cold water, preferably just above
freezing to comply with the letter of the challenge.
Emerse the can into the boiling water, taking care to leave the top out
of the water. You may see steam from left-over soda escaping.
After about a minute, carefully but quickly lift the can out of the water
and slap it upside-down into the ice cold water. It's critical
that the entire top of the can be submerged in the water at once and rapidly.
From right side up in the boiling water to upside down in the ice water
should be done in well under a second.
If you perform the experiment correctly, there will be a loud BANG! as
the can implodes in on itself.
Why? Air pressure is inversely related to air temperature. All things
being equal, a volume of air at a higher temperature exerts a higher pressure.
When you heated the can, the air expanded, equalizing pressure with the
room by escaping out the top.
When the can quickly cooled, the air pressure inside the can fell immediately.
It sucked some water through the opening, but not quickly enough. The
can, with a very low internal air pressure, was literally crushed by the
air in the surrounding room.