I was a science teacher and desperately miss coming up with the bizarre activities.
My thoughts are giving the kids practical problems to solve. the ones that come to mind would be have the kids solve some basic salvage problems on paper and then try them out in real life. The girls would have to determine all the parameters and calculate the solutions and then test them out.
Most of this is about calculating density of different objects and materials.
Ask them to raise a metal object (something like a metal pedal car, sub mock-up or a piece of jungle gym). They'll need to identify all the parameters and either measure the density or weight of objects or research the what they need to know about the problem. The challenge will be to figure out the exact amount material required to raise the car.
For example you tell them that some submarines can dive down thousands of meters. Air is not practical for boyancy because it is very compressable and at extreme depth it is not easy to shift around. Instead, you want them to raise the car (or sub or whatever) to the surface using different liquids. You could tell them that they need to calculate the exact amount of fresh water to provide enough lift to raise the car in local sea water. They would have to figure out exactly how dense the local seawater is. how much does the car (or sub) weigh, how negative is it in water and how much freshwater would be required to lift it. It would certainly keep them busy researching and testing. and the final exam for the unit would be the practical test of their research.
mmmmm love to have the chance to work on this unit...
---------- Post added September 28th, 2013 at 07:58 AM ----------
Be careful with this one, the cap of a soda bottle shouldn't blow off but if it does it will be a dangerous projectile, that or the bottle may rupture sending pieces flying. Although more likely the pressure delta won't be enough to do anything other than make the bottle very firm.
The other ones from Doc and others sound great though. And props to you for being an awesome science teacher, this is all way beyond what most teachers do and I think its great that you're doing so much to inspire your students.
I used to teach a bottle rocket unit. The failure pressure on a your average soda bottle is around 200 psi. To have the bottle rupture you would need fill it at a depth of about 445 fsw. From 100 fsw the bottle will be at about 45 psi. If the bottle did fail it would definitely qualify as dangerous.
Oil rig worker that I knew would draw on Styrofoam cups and attach the to the outside of inspection ROVs and send them deep. The cups would compress to thimbles and on surfacing the Styrofoam cells would rupture and they would stay tiny. You could try something like that with a syringe or balloon attached to the anchor so they could see the gas compression. A 60 cc syringe would give them a good amount of compression at 66 fsw (20 m)
---------- Post added September 28th, 2013 at 08:07 AM ----------
The first thing that popped into my mind was to compare the acceleration due to gravity in air (ie on surface) with the acceleration due to gravity underwater. then extend that idea to the force of resistance in a fluid. If you can do a comparison with the acceleration due to gravity in a (near) vacuum then you have the trifecta.
BTW I am a professor of Physics so if you want help working out ideas be in touch.
cheers
Jerry
An electronic fishing scale attached to different fish shapes might be interesting in comparing the hydro dynamic of different fish bodies. Connect the form of fish (and resistance) to its life style might interesting. open ocean versus reef fish of different lifestyles. The good news is you could get plastic toys to work with and give you some great data.
