What You Need
An empty plastic 2-liter soda bottle with cap
Lots of Ice
Pitcher of ice water
1/2 c. boiling water
9x13 casserole dish
Fill the 9x13 dish with ice.
Pour the boiling water into the empty bottle; we used a funnel. Let sit for 2 minutes.
Seal the bottle by putting the cap on tightly.
Now lay the bottle on its side in the pan of ice.
Pour the pitcher of ice water over the bottle.
Pick up the bottle by the cap to examine it. It's been crushed without you even touching it!
Why it Works
The boiling water heated up the air inside the bottle and once capped, the hot air was trapped in there. When the bottle was placed in the ice and cold water poured over it, the air in the bottle began to cool down, thus decreasing the air pressure inside the bottle (cooler air expels less pressure than hot air). When the air pressure in the bottle decreased more than the air pressure outside the bottle, there was more force pushing in on the bottle than pushing out, thus collapsing the plastic.
This great experiment came from the amazing site Cool Science Experiments Headquarters. Stop by and check out all the phenomenal activities and inspiration there!