Let's take a packet of hot sauce or ketchup from a local fast food joint and turn it into a cool science toy. We will learn about air pressure and density as we make a Cartesian Diver also known as a Condiment Diver. Amaze your friends as you make the packet rise and fall at your whim.
Materials - Clear Plastic 1 Liter Water Bottle and Cap. - Small Plastic Pipette - 1/4 inch hex nut - Can Use Ketchup or Hot Sauce Packs (the fast food type) instead of pipette / nut. - Water - Plastic Bottle and Cap
Watch Video: Make Cartesian Diver
Process To Make A Cartesian Diver
1) Cut the long piece off the pipette near the bottom leaving the larger / fat tube part.
2) Fill the pipette about 1/2 full with water.
3) Secure the hex nut on the bottom of the pipette.
4) Fill the bottle with water.
5) Put the Cartesian diver (pipette and hex nut) inside the bottle with water. The diver should float inside the water bottle because of the small air bubble in the pipette. If it sinks then let a little water out of the pipette. If you don't have a pipette and hex nut, then use a hot sauce or ketchup pack from a fast food joint.
6) Screw the cap on tightly.
7) Grab the bottle by the sides in the middle and squeeze.
The Science Behind The Cartesian Diver:
When the manufacturers seal the packets of hot sauce or ketchup tiny little pockets of air bubbles are trapped inside. When we squeeze the sides of the plastic bottle water is pushed against the side of the condiment packet. The air molecules / bubbles shrink as a result of the increased pressure. The volume inside the packet is lowered as we squeeze the bottle. As a result the packets density is raised and it sinks down to the bottom. The reverse happens when we stop squeezing. The pressure is reduced and the air molecules / bubbles expand again. Density is lowered and the packet floats again. Now go make a Cartesian Diver with some friends!