We love recycling around here, so we thought we’d give our bin a little leg up and crush the cans with the forces of the natural world! Before you take this on at home, make sure you have the proper safety precautions and the help of a responsible adult.
6 rinsed out pop cans. You can use more or less cans depending on how many times you want to implode the cans and how many you have available.
A stove burner
A clear glass bowl
Tongs and/or work gloves
A small recycling bin for crushed cans
1. Fill pop cans with just enough water to cover the bottoms.
2. Put pop cans on top of the stove burner.
3. While the cans are heating up, put water and ice in a glass bowl.
4. Wait for water vapor (not steam!) to appear in the cans. Use the tongs to bring a can over to bowl. Carefully and quickly flip over the can so the opening is over the water and then dunk it in. Warning: The aluminum will be hot! Make sure to never touch it directly!
5. Watch as the can implodes, crushing inward! What made that happen? You can repeat this with your other cans one at the time to watch the reaction.
How does it work?
Here’s the real scoop on the science behind the imploding can. Before heating, the can is filled with water and air. By boiling the water, the water changes states — from a liquid to a gas. This gas is called water vapor. The water vapor pushes the air that was originally inside the can out into the atmosphere.
When the can is turned upside down and placed in the water, the mouth of the can forms an airtight seal against the surface of the water in the bowl. In just a split second, all the water vapor that pushed the air out of the can and filled up the inside of the can turns into only a drop or two of liquid, which takes up much less space.
This small amount of condensed water cannot exert much pressure on the inside walls of the can — and none of the outside air can get back into the can. The result? The pressure of the air pushing from the outside of the can is great enough to crush it! Amazing, right?
The science of implosion
The sudden collapsing of an object toward its center is called an “implosion.” Nature wants things to be in a state of equilibrium (a fancy word for balance). To cause the internal pressure of the can to balance with the can’s external pressure, the can implodes. That’s right — air pressure is super powerful!
You probably noticed that the can was filled with water after it imploded. This is a great illustration of how air pressure is pushing all around us. Specifically, the outside air pressure was pushing downward on the surface of the water. Since the air pressure inside the aluminum can was less than the pressure outside the can, water from the bowl was literally pushed up and into the can.
Outside air pressure and drinking from a straw
This action is similar to what happens when you drink from a straw. Although we say we are “sucking” liquid up through the straw, we really aren’t. To put it simply, science doesn’t suck — rather, it just pushes and pulls.
Outside air pressure is pushing down on the surface of the liquid. When you reduce the pressure in your mouth (that sucking action), the outside pressure is greater than the pressure inside your mouth. For that reason, the liquid shoots up through the straw and into your mouth.
The same thing is true with the can in our can-crushing air pressure experiment. The outside air pressure pushing downward on the surface of the water is greater than the force inside the can and the water gets pushed up into the can.
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