Atmospheric Pressure and Bernoulli
- Soda bottle collapse
- Magdeburg hemispheres
- Stick cylinder to hand
- Guinea & feather tube
- Bubbles - Receipe
- Bernoulli effect: balls in a stream of air.
- Bernoulli effect: funnel & balls
- Curve balls
- Large glider
A 3-liter bottle is easily crushed by atmospheric pressure when
to a vacuum pump. Free one gallon metal cans are hard to find these
The five inch diameter plates would require a force of nearly 300
pounds to separate them if it were a perfect vacuum and seal, in fact
half that is all that's needed.
Burning Paper in a Measuring Cylinder
Drop a piece of burning paper into a measuring cylinder and then
cover the open end with your palm, or other part of your anatomy. I've
used the top of my bald head and my belly. The flame extinguishes once
the oxygen is used up. When the gases in the cylinder cool, the
inside drops, sticking the cylinder to your body. It's a cheap
of atmospheric pressure, but don't leave the cylinder on too long or
have a vivid demonstration of the pressure within blood vessels.
Guinea & Feather Tube
In this classic demonstration a feather and a coin are dropped in an
tube. As objects at the same location have the same weight to mass
hence they have the same acceleration in a vacuum.
I'm not sure what the Physics is here, but it's a wonderful
of something. (Okay, it could lead into surface tension, thin film
evaporation rates, minimum area topology, etc. I just like bubbles.) A
paddling pool with a small step stool placed in the middle may be
substituted for the custom made fiberglass tub, but be careful when
on or off. Use a hula hoop for the bubble hoop, a piece of broom handle
is fastened to the hoop with a single screw and then electrical tape is
wrapped over that section to cover any sharp edges on the screw. I'm
that it helps to wrap the hula hoop in gauze, I can believe that.
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- 1 cup Joy or Dawn dish washing liquid
- 3 - 4 tablespoons glycerine (optional, obtain from pharmacy)
- 10 cup clean, cold water (up to 50% more on a dry day)
Bernoulli Effect Demonstrations
Use a shop vac to support a 4 inch diameter foam ball in the air.
surface balls work best. Large balloons of the 'punch ball' variety
work well in a room with a high ceiling. The faster a fluid moves, the
lower it's pressure gets to be, all else being equal. The angle of
is just as important for plane wings, as regards lift and the seams on
the base ball drag the air around making curve balls possible.
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