Sponsors:
Stow 2001-2002
Density DiverPowerpoint Presentation | Meet the team
The Exhibit
This exhibit is a big Cartesian Diver. A smaller Cartesian Diver can be made from a bottle of water with a small amount of air, into which a small glass tube is inverted so that the glass tube is just floating, with some water and some air. When the bottle is sealed and squeezed, the pressure inside the bottle increases, squeezing the air inside of the glass tube. The overall density of the glass tube (glass, water, and air) becomes greater than the surrounding water, and the tube sinks to the bottom.
The Design Process
The team began brainstorming for ideas that show concepts of density. Ideas included hot air balloon and convection currents, which were both difficult to implement because they require heat. After several brainstorming sessions, they agreed on making a large Cartesian Diver, which requires no heat and still demonstrates density.
The team prototyped with various materials and adhesives to see which worked. One of the major questions was how can children apply pressure to the large tank of water? Some ideas included a foot pump, a piston-cylinder type device, and electric air pump. The team decided on using a lever to push down on an elastic membrane. This introduced another question: what was a suitable material for the membrane? The material needed to be strong enough so that it didn't rip, but elastic enough so that it can be stretched by a child. The team experimented with various rubber membranes to find the best one.
Related Links
Physics and Cartesian Divers
[http://collections.ic.gc.ca/science/english/phys/
projects/pressure.html]Pictures and Directions about Cartesian Divers
[http://www.physics.purdue.edu/demo/2B/
cartesian.html]Little Shop of Physics
[http://littleshop.physics.colostate.edu/Cart.html]Directions about Cartesian Divers
[http://www.fatlion.com/science/cartesian.html]New England Aquarium
[http://www.neaq.org/]
