Science Experiments
The World of Wonders Science Museum will be posting a new science experiment each month that you can do right in your own home!
Cartesian Diver - The Diving Airhead
A Cartesian Diver is an item (often open at the bottom) that barely floats in a closed, mostly full, flexible container of water. When the container is squeezed, the diver goes down; when the container is released the diver rises again.
To make a Diver:
- Get a 2 liter plastic soda bottle, a tall glass of water, and a glass eyedropper with a rubber bulb.
- Fill the soda bottle almost completely with water.
- Fill the dropper with water so that it barely floats in the glass of water.
- When the dropper floats just right, drop it in the bottle and close the lid tightly.
- Now when the bottle is squeezed, the diver should dive; when the bottle is released the diver returns to the surface. Careful squeezing puts the diver in the middle.
- Notice what happens to the water level in the diver when the bottle is squeezed. The rising water level in the diver packs the air together and adds extra stuff (more water) to the inside of the diver. This makes the diver more dense, causing it to sink.
Application to the Real World
Submarines work on this same principle. In addition, fish have a bag of air inside them that acts like a diving airhead. A fish can change the size of its "swim bladder" by gulping or burping air, by absorbing air into or out of, the bladder from its blood stream, or by squeezing or relaxing the swim bladder. In this way a goldfish doesn't have to actively swim to stay at a certain level in the fish bowl. It can simply adjust its density using the swim balder and "hang around" at any level in the water.
Snowflakes in a Bottle
Our first experiment comes
from Caltech, and shows us how fun and easy it is to make our own
snowflakes with some dry ice, a soda bottle, and Styrofoam cups.
This experiment teaches how snow forms, along with a great understanding of ice, dry ice, CO2, and more. And it's perfectly safe and fun for the family.
Try the experiment at SnowCrystals.com.