Tornado Bottles
| Physics: | Vortexes |
| Grade Range: | Elementary School |
| Format: | Hands-on |
A simple, easy, and all around fun demonstration that all elementary students love. Be cautious of students being too rough on the demo, or you may end up with spilled water all over the floor!
Materials
- Tornado Bottles
- Empty 2-liter Bottles
- Bottle Connector
- Water
Safety Precautions
Please read the General Safety Precautions section of the Demonstration Safety page before performing this demonstration.
Demonstration
- Preparation
- If the Tornado Bottles are not already made, then fill one 2-liter bottle 3/4 full with water and connect the two bottles using the bottle connector. Optionally, you can make the tornado bottles more interesting by dyeing the water or adding tiny rainbow sparkles.
- Presentation
- Allow students to come up and use the tornado bottles. Show them how to turn the bottles over and make a "tornado" inside the bottle! Provide explanations as needed.
Why This Works
A Vortex is a spiral that can form in moving fluids, which allows for large amounts of material to be transferred quickly. We often see vortexes when water is going down a sink drain or a bath drain, since water is a liquid, adn we know that liquids are fluids. They can also form in moving air, such as dust spirals on a windy summer day or leaf spirals on a windy autumn day. This is because the air can act like a fluid too!
In this demonstration, we have one bottle filled with water and another filled with air. When the bottles are flipped at first, the water is trying to push down while the air pushes up. If the bottles aren't swirled, the water will only trickle slowly down, with a slow stream of bubbles go up. Once the bottles are swirled, a vortex can start to form, which allows the air to go quickly up the center, while the water goes quickly down the sides!
- Trick question for students: Why does the water go down the walls, while the air goes up the center? Why doesn't the water go down the center, while the air goes up the walls?
- Answer: Water has strong Surface Tension, which means that the water molecules like to stay connected to each other if possible. When the water is passing through the hole in the bottle connector, it will cling to the wall to avoid splitting into drops, because that keeps the surface tension from breaking!
Additional Information
- This demonstration pairs well with the Vortex Cannon and the Tornado Box demonstrations
- Make sure students know that they can do this demonstration at home! Bottle connectors are often sold at craft stores, so students can easily make this at home with their parents!