Cartesian divers

August, 21 2012
Anna Durham and Alicia Snyder
In order to complete this experiment (Cartesian divers) you need the following.
1. A two liter bottle (any size will work, but this size will yeild the best results.)
2. Water.
3. Pipettes.
4. Washers.
5. Tape
There are no safety concerns for this experiment. A little bit of water may splash.
Steps to successfully complete this experiment.
1. Fill a 2 liter bottle with water
2. Tape washers to pipettes, just below the bulb.
3. Put water into each pipette. different amounts in order to see what works best.
4. Put a pipette into the 2 liter bottle. . MAKE SURE THE PIPETTE FLOATS!
5. Screw the lid on tightly and squeeze the bottle.
Note: you can change the amount of water in the bottle and in the pipettes in order to see which works best. more water in the bottle = sinking faster.
Why does this work?

When the sides of the bottle are compressed, water is forced into the empty space in the pipette. As a result, the air is compressed and the extra water makes the pipette more dense. This causes the pipette to sink. Once the pressure on the bottle is released the air inside expands to its original size and the water is forced out of the pipette. As a result, the pipette becomes less dense than the water and floats to the top.
Flinking and "Rescue Mission"
Flinking is not quite floating and yet not quite sinking. I have a few theories about how to accomplish flinking. Find how much water it takes in order for it to sink then find the floating amount. Then add a bit more gradually to the pipette and drop it in. Repeat until you get the right amount. The rescue mission was fairly difficult, we could not get this one to work properly. We used regular length pipettes which I believe was one of our problems. When trying to do this it takes an extreme amount of patience and hand-eye coordination.