State of the Balloonion
Contributed by Alex Thomas
Experimenting balloons filled with different states of matter (solids, liquids, and gases) can tell us some surprising and interesting things about these!
- Pump up one balloon with air to a small size.
- Fill up another balloon with water to a similar size. If it’s difficult to fill, try stretching it with your fingers and then filling it with water. Stretching makes it easier for the balloon to expand from the water pressure.
- Fill up a third balloon with water to be slightly smaller. Put this in the freezer and leave it for a few hours or overnight. Water expands when frozen so it will be the same size as the others.
- Once you have your three balloons you’re ready to start experimenting!
- Place the air balloon on a flat table. Twist the balloon and see how well it spins.. Write down some observations about how long it spins for, if it falls over, if it leaves the ground and anything else that you find interesting.
- Try the same thing with the water balloon. Record your observations!
- Try the same thing with the ice balloon. What do you notice? Sometimes, the balloon will not freeze in a spherical shape and will be too flat in areas. If this happens, try to avoid spinning over these areas so it rolls better.
What we expect:
We expect the ice balloon to spin the best. It’s heavy and can remain in one place as you twist it up. The air balloon is too light so it may just blow away and you can’t twist it very well. The water balloon absolutely refuses to spin.
Why this happens:
The ice balloon is locked into a solid structure that keeps everything together, like a bridge or fence. When you spin the outside of it, each water molecule pulls the next one and the balloon spins. However, liquid water particles aren’t locked together so when we spin our water balloon the water can expand and compress creating turbulence. If we did this fast enough, the water would actually dip at the center and begin to look like a whirlpool. This is called a forced vortex and it uses up our energy so the balloon can’t spin for long. The air balloon is much lighter than the other two. Friction depends on how hard something is pushing against the surface so a lighter balloon has less friction. To see this, place your hand on the table and try to move or turn it. Then push really hard against the table and try again, notice it’s a lot harder. For our balloons, that means the friction with the table isn’t strong enough to hold the balloon in place and spin it. Even if the balloon were to stay in place it still wouldn’t spin as well as the ice balloon. That’s because the air particles are free to float around just like water balloons did. Since they’re a lot lighter, it’s a smaller problem but it still limits how long the balloon will spin for.
Try spinning the balloons in water. Which float and which sink? How do they spin now?
Try rolling the balloons. You can go up and down a slope or across level ground. Which balloon goes further? Which turns the most?