This super simple experiment seems almost magical, but don’t worry, it doesn’t require a magician! It can only be explained through a better understanding of air pressure.
Even though most of the time you can’t see or feel it, the air around us is pushing against every surface and by making a change in air pressure, we can crush a plastic bottle without ever touching it.
Note: Because this experiment requires the use of boiling hot water, depending on the age of your child, adult participation is very important.
- Empty 2-liter plastic bottle with lid
- 6-8 cups of Ice
- 1/2 cup Hot Water (bring it to a boil before you start the experiment)
- 8×11 pan
- Pitcher of Ice Water
Step 1 – Gather your materials together and begin by filling your 8×11 pan with ice.
Step 2 – Carefully, pour 1/2 cup of the hot water into the 2-liter bottle. After the water is in the bottle, wait for 2 minutes. As you are waiting make some observations. What happened to the bottle when you poured in the hot water? What do you think is happening to the bottle during the 2 minutes you are waiting?
Step 3 – After two minutes have passed, screw the lid back on the bottle. Make sure that it is on tight.
Step 4 – Next, lay the bottle on its side in the pan full of ice. You may need to hold it in place.
Step 5 – Slowly pour the pitcher of ice water onto the bottle. Take a moment to make more observations. What happened to the bottle when you poured the ice water on it? Did you hear any noises? Did it change shape?
Step 6 – Stand the bottle up to get a closer look. What happened to the bottle? Why do you think the plastic bottle crushed in?
The atmosphere is heavy! The weight of the air that is pushing down on all objects on Earth all the time is more than the weight of three cars combined! Imagine that the air pressing down on the top of your head right now is more than the weight of three cars combined. How do objects on Earth not get crushed by this air pressure?
Pressure is the force pushing down on an area or surface.
Air pressure is the weight of a column of air pushing down on an area.
Air pressure is not able to crush objects on Earth’s surface because the molecules in air push evenly in all directions – up, down, sideways, diagonally. The air pushing out of your body is equal to the air pushing in on your body (that’s how you don’t get crushed by the atmosphere).
In this experiment, you get to see how powerful air pressure really is when you take away the ability of air molecules to push evenly in all directions.
Before adding boiling water to the bottle, the bottle was filled with room temperature air. Once the hot water was placed in the bottle, it heated up the air inside the bottle. When we put the cap on the bottle, the hot air is trapped inside the bottle.
When we placed the bottle in the ice and poured cold water on it, the air inside the bottle began to cool down rapidly. The cool air exerts less pressure than hot air, therefore the air pressure inside the bottle began to decrease.
The air pressure inside the bottle decreased to the point where it was less than the air pressure outside the bottle. Therefore, the air pressure pushing in was greater than the air pressure pushing out, causing the bottle to be crushed!
More Science Fun
If you are looking for more experiments dealing with Air Pressure then you’re in luck. Check out these other fun and simple experiments we’ve done.
- Use a simple science “trick” to easily stab a regular drinking straw through a raw potato
- Or turn a Water Glass upside down without spilling the water!
- And you can even make a balloon fly across the room like a rocket.
I hope you enjoyed the experiment. Here are some printable instructions: