We need a Science Fair Project

[spiderman]

My 14 year old son needs a science fair project. He is a diver and wants to do something underwater. Any good ideas?

[Wendy]

a demonstration of one of the laws of physics pertaining to diving, like have a clear tank and submerge a baloon in and show how pressure makes it smaller and explain why

[Charlie99]

Another simple one is the "Cartesian Diver". An object (perhaps something looking something like a scuba diver) just a tad bit positive buoyant, and with a gas bubble inside, is put inside a container of water with a rubber cover over the top. Press on the rubber cover to increase the air pressure inside the container. This makes the gas bubble inside the object get smaller and it sinks.


Another alternative -- get some high helium content trimix and do the Donald Duck thing, along with an explanation. You might also just get some helium intended for retail use in balloons. In a lot of places that has 20% O2 so you won't pass out if you breathe it.

[teknitroxdiver]

Um, yes lots of places use heliox for balloon use, but without an analyzer, how are you going to know?

If you can be sure of the mix--borrow an analyzer or ask the gas company to analyze it--that would be a really cool project. In fact, I've thought of doing that for the next one I have to do.

Of course, you could just get some balloon helium and if he gets light-headed have him stop breathing it

[Don Burke]

I have heard that story too and I doubt any balloon gas other than air has 20% oxygen.

It would be just too hard to get a balloon off the ground with heliox 20.

[teknitroxdiver]

Some places do use heliox, some guys got some a put an analyzer on it and it came back 21% O2, but this is probably a few-and-far-between deal.

[GoBlue!]

Ah, brings back memories. Age 13, filling up helium balloons at a Health Fair....my buddy put his mouth right on the tank nozzle & took a long, slow, deep breath. We heard, "hehe hehe...this stuff makes you feel funny....woooo...." and then watched him pass out into a flower bed. Classic.

Jim

[Maya]

My son did 2 different science projects in middle school pertaining to diving. In one, he demonstrated Boyle's law with a balloon at varying depths (and an u/w photographer taking pictures of him with balloon at each depth)..in another, he created a plexiglass frame in which he placed large swatches of the color spectrum and took pictures at varying depths using ambient light...then repeated the process with a flash. He had a lot of fun with both projects.

Another project he considered was to create a grid and keep track of the flora/fauna within the grid. And yet another was to create an artificial "reef" within a grid and keep track of the critters it attracted.

Just a few ideas.

[ChrisA]

My 14 year old son needs a science fair project. He is a diver and wants to do something underwater. Any good ideas?

One simple thing that will educate many adults is to place a full scuba tank on a bathroom scale, weigh it then let the air out and note how much lighterthe tank gets. Many people don't think air has weight. You can showthat it does and you can then explain why there is approx 14 PSI at sea level.

The under water bolon thing is pretty good but get a deep, clear tank. and then put a pully
fixed to the tank bottom. People can then pull a string and watch the bollon shrink
as they pull it down. Interactive displays are great.

[Bob3]

Hauling a deep enough tank into the school may be a bit tough, snapping pics & doing a slideshow/powerpoint presentation would be more practical.
If you could get your mitts on a pressure testing fixture, lacking that a vacuum pump w/ bell, some interesting pressure related projects could be whipped up.
I also like the "growing stuff" suggestion; there are some things inhabiting the rear area of my frige I could donate, the stuff would probably grow fine underwater, & they might even discover a new species if the CDC or EPA didn't quarantine the place.