demostrating bernoulli's principal

[mopherman]

i was assigned to demo Bernoulli's principal of moving fluids to my class. So far ive come up with blowing air over a box with a light power in it and watching the powder fly away. but the flour settles too fast to be much good. I'm currently whipping up an agitator for the flour, but im open for sujestions as to how do demo the principal.
PS: I know, cloud. dont bother as my school hates projectiles.
thanks

[potatoflinger]

Try having a "T" shaped set of tubes, with flour in the "l" part of the "T" and air from a compressor going in at one end of the top of the "T", and a "barrel" going out the other side. The air should suck the flour out of the tube and blow it out the "barrel". It isn't really a projectile, since it's flour and couldn't really hurt anything, unless you used it like a sandblaster.

[hi]

when i did it i put a ping pong ball into a very curved glass and i could get it to move just by blowing into the glass.

[mopherman]

alrighty, project update!
I just epoxied a motor the the bottom of my clear box and im going to attach a flap to agitate the flour when the liquid nails dries.

[jackssmirkingrevenge]

why not a wing that can slide up and down over a couple of rails, and a motor blowing air over it - or too obvious?

[Spitfire]

Simple.

1) Get a tap and a spoon.
2) Open tap
3) place curved part of spoon into the flow of water.
4) Bernoulli's principle has just been demonstrated, as the spoon moves, or rather gets sucked into the waterflow, ie lower pressure

[Jared Haehnel]

How about a ping pong ball and an upside down funnel... you hold the ball in the mouth of the funnel and blow air through the funnel with your mouth. Let go of the ball and it will stay there... demonstrating Bernoulli's principle...

I hope I'm thinking of the right dead science guy....

[jimmy101]

Other possibilities ...

If you have a faucet and sink. Build (or buy) an aspirator. A T should work though you might need to either get a T with a small bore side arm or partially plug the sidearm to reduce it's ID.

Connect some pressure hose (like the small ID white hose used to deliver water to a frig's ice maker) to the sidearm of the T. Glue (epoxy, tape....) the other end of the hose into a hole drilled in the cap of a 1 gallon plastic milk jug. Screw the cap on the milk jug.

Turn on the faucet and the aspirator will suck the air out of the milk jug and it'll collapse. This is a demonstration of the Bernoulli principal and the venturi affect.

If you are dong this in a science class there is a good chance the lab already has an aspirator setup like this. This type of aspirator will pull a vacuum down to whatever the vapor pressure of the water is, typically about 25 Torr (~0.03 ATM).


Other things that have aspirators that you might have laying around already;
1. Garden chemmical sprayers, the kind that you attach to the garden hose and put chemicals in a bottle.
2. Spray bottles for liquids like Windex.
3. Paint sprayers.

[mopherman]

OK, demo went well today. i did manage to kill my last hobby motor with baking soda though