Science Fair Project: Air Pressure Crushing Cans

A can’s interior is filled with water and air particles. By heating it, the water inside the can will change its state from being a liquid to a gas, becoming water vapor. The water vapor will push the air that was originally inside the can out into the atmosphere. When the can was turned upside down and placed into the cold water, the water vapor condensed and turned back to its liquid state. Since the water molecules in this state are much closer together, it will take up much less space. With small amount of water, there is not enough pressure on the inside walls of the can, resulting in the outside air pressure crushing the can.

Crushed Cans


This is the process in why an object suddenly collapses towards its center. Most objects desire the state of equilibrium or balance, which is why the internal pressure of the can will want to balance the external pressure of the can, causing the can to implode. Notice that the cold water in the bowl will shoot into the can, which is similar to drinking liquid with a straw. The outside air pressure is pushing down towards the surface of the liquid. The “sucking” action reduces the pressure in your mouth and the outside air pressure becomes greater, which causes the beverage to shoot through the straw and into our mouths.

  • How does air pressure crush cans?
  • Empty soda cans
  • Stove or heated plate
  • Cooking tongs
  • Gloves
  • Bowl
  • Cold water

Air Pressure


  1. Firstly, rinse the can thoroughly.
  2. Next, add 1 tablespoon of water into the can (make sure it is just enough to cover the bottom of the can).
  3. Then, fill the bowl with cold water.
  4. With the help of an adult, place the can onto a stove and start heating the water. After you hear the bubbling sound of water boiling and water vapor rising from the can, continue to heat the can for 1 more minute.
  5. Turn off the heat and lift the can up with the tongs. Quickly turn the can upside down and submerge the mouth of the can down into the bowl of cold water.
  6. Record your results. How much interaction occurred?

Smart Tip: Take pictures for each step of the process to show the visual transformation of the can.