Demo or Problem Suggestions ??

[-=>Larry<=-]

Hi Folks,
I foolishly signed up to teach an intro physics class this semester [after 20+ years of research and graduate type of work!]

I was thinking it might be a bit fun to blend in some diving related demos or problems! The perfect gas laws and the refraction discussion in the other thread seem naturals - - - but I'm hoping you folks have some good alternate suggestions!

Thanks

 

[IndigoBlue]

Hi Folks,
I foolishly signed up to teach an intro physics class this semester [after 20+ years of research and graduate type of work!]

I was thinking it might be a bit fun to blend in some diving related demos or problems! The perfect gas laws and the refraction discussion in the other thread seem naturals - - - but I'm hoping you folks have some good alternate suggestions!

Thanks

ROY G. BIV is a good refraction discussion, as you said.

Boyle's Law for the balloon going to depth, as you said.


Amundsen's Law (not sure if I spelled this right) for temp/pressure relations regarding filling your tank at room temp then diving with it at ocean temp.

Dalton's Law of partial pressures, regarding PN2 value for narcosis, and PO2 value for oxygen toxicity risk. You can use the PN2 at 80 ft as normal, and show them how depth increases the PN2 which is then manifests itself in increased narcosis. Oxygen is more difficult, and you just need to show them the NOAA benchmark of 1.4 and compare to that for deeper depths.

Archimedes Principle, known as the law of floating, for neutral buoyancy and for salvage recovery.

Liquid density of seawater or freshwater, and volume of air required to recover a sunken object like a boat motor or anchor. We use 64 lb/sq ft for seawater and 62.4 lb/sq ft for fresh.

The ratio of seawater to freshwater density (1.02564) in adjusting wetsuit weighting from a pool to the ocean, or vice versa from the ocean to a lake.

 

[Foo]

Larry,
I can't add to this subject except to say that perhaps you might want to invite IndigoBlue to be a guest speaker? The more I read here, the more I realize that I don't know squat.

Diving is so cool.
Foo

 

[devilfish]

Hi Folks,
I foolishly signed up to teach an intro physics class this semester [after 20+ years of research and graduate type of work!]

I was thinking it might be a bit fun to blend in some diving related demos or problems! The perfect gas laws and the refraction discussion in the other thread seem naturals - - - but I'm hoping you folks have some good alternate suggestions!

Thanks

Larry,
Build a Cartesian diver. It's simple and it's perfect for a graphic demo of Archimedes Principle and Boyle's Law.

BTW, ROYGBIV is absorbtion not refraction.

 

[klausbh]

There is an entire chapter on underwater physics in the us navy diving manual, complete with sample questions, etc. Take a look here :
http://www.coralspringsscuba.com/usn/Chap02.pdf

-Klaus

 

[-=>Larry<=-]

Some of that is probably beyond an intro class - but I'll have fun anyway! Definitely some extra stuff as we brush by optics and maybe even some mechanics type applications!

IndigoBlue: Where are you? Foo thinks you'll be a good guest speaker - are you ready for about 80 teenagers! Come'on down - We could even have a nice little dip in Aquarena Springs beforehand - but I don't think I can get the class there!

Thanks for the help - Keep the good suggestions coming!

 

[perpet1]

here is an interestng demo a friend of mine used to do. take a sealable flexible container, for her demo she used a 2L pop bottle and fill it 100% with water (fresh water is fine).

Now comes the tricky part. Create a capsul (little semi clear boloon works well for this or even a condom) that will fit in the opening of the bottle. Place a little weight in the contaner like a little sand.

This is where you will have to play a bit to get it right but you want to have enough air in the capsul that it is just posativly buoyent in the water you placed in the 2L.

Now place the capsul into the 2L (it should float at the top) and seal the 2L.

Now you apply pressure to the outside of the container ( or you can get fancy and attach a pump to the cap to increase pressure indide, thus demonstrating Pascal's Principle (not diveing related and but cool none the less). In any case if you set everything up right by increasing pressure inside you shrink the air volume in the capsul and the object will sink. Remove the pressure source and capsul will float.

Or you could spend a few hours talking about a lava lamp which is just as cool.

 

[neil]

here is an interestng demo a friend of mine used to do. take a sealable flexible container, for her demo she used a 2L pop bottle and fill it 100% with water (fresh water is fine).
Now comes the tricky part. Create a capsul (little semi clear boloon works well for this or even a condom) that will fit in the opening of the bottle. Place a little weight in the contaner like a little sand.
This is where you will have to play a bit to get it right but you want to have enough air in the capsul that it is just posativly buoyent in the water you placed in the 2L.
Now place the capsul into the 2L (it should float at the top) and seal the 2L.
Now you apply pressure to the outside of the container ( or you can get fancy and attach a pump to the cap to increase pressure indide, thus demonstrating Pascal's Principle (not diveing related and but cool none the less). In any case if you set everything up right by increasing pressure inside you shrink the air volume in the capsul and the object will sink. Remove the pressure source and capsul will float.
Or you could spend a few hours talking about a lava lamp which is just as cool.

That's essentially a Cartesian diver. I use a piece of 3mm neoprene cut into the shape of a diver, and weight it with wire solder so it just floats. Then when you squeeze the bottle the diver descends. This demo covers important issues for divers. To ME this more obviously demonstrates Boyle's law than Pascal's principle. I also use a simple balloon in a bottle.
Neil

 

[Wreckie]

Loud and graphic: crack the valve wide open on a small cylinder (pony or similar) watch it ice up and start spitting ice.

 

[perpet1]

That's essentially a Cartesian diver. I use a piece of 3mm neoprene cut into the shape of a diver, and weight it with wire solder so it just floats. Then when you squeeze the bottle the diver descends. This demo covers important issues for divers. To ME this more obviously demonstrates Boyle's law than Pascal's principle. I also use a simple balloon in a bottle.
Neil

The only to really show pascal's principal is to build a pump into the cap which would add pressure to the surface of the water (vs. sealing the cap and squeezing the bottle)

But a cool demo either way.

Pete