James Clerk Maxwell postulated that since heat involves the movement of molecules, it might be possible to separate hot and cold air in a device with the help of a "friendly demon" who would sort out and separate the fast and slow moving molecules of air. The vortex tube is such a device and does exactly that — using compressed air as a power source, it has no mechanical moving parts and produces hot air at one end and cold air at the other.
How it works:
Room temperature compressed air is supplied to the vortex tube...
Irregular lamina with marked center-of-mass tossed in air.
What it shows:
The center of gravity fixed in (or outside) the object always orients itself with minimum potential energy on a vertical line below the support point. When an irregular shape is thrown into the air, it is seen to rotate about its marked center of gravity or center of mass (COM).
How it works:
We have several irregular lamina to suspend and/or throw in the air. They are (1) an amoeba shaped piece of masonite pegboard, (2) a cut-out map of the U.S. glued...
Also known as the Ben Franklin pond experiment, after a story in B.F's autobiography.
Olive oil with a known volume is dropped onto water. The water has been dusted with lycopodium powder, which floats on the surface. The oil drop expands, pushing the powder aside to form a clear circle, until the oil forms a monolayer. Measuring the area of the monolayer, dividing the volume of the drop by that area, gives the thickness of the monolayer, which is the height of the oil molecule on water.
From our demonstration movie, we found these values. The size of the patch was 62 cm...
Observation of phase changes with corresponding pressure changes.
A two ml. plastic microcentrifuge vial and a small shop vise are used together to melt dry ice.
Wear safety glasses for this demo. The vial can explode, or shoot out of the vice, from the pressure of liquid carbon dioxide. Set up a camera with a close shot of an empty vial before putting in a loaded vial.
Crush a pellet of dry ice to make pieces that fit into the vial. Place a couple of pieces in the vial, and snap the lid closed.
Immediately place the vial horizontally in the jaws of the vice,...