Allow a board to rotate under the force of gravity and the free end will accelerate at a rate greater than g. Relation between angular acceleration and linear acceleration seems to give free-fall paradox. Read more about Falling Faster than 'g'
One can show that the period of oscillation of an object doesn't change for different suspension points, as long as they're the same distance from the COM. This is consistent with what the parallel-axis theorem tells us about the moment of inertia of the object. Read more about Parallel-Axis Theorem
Ink is squirted into a fluid and mixed in until it disappears. By precisely undoing the motions in the reverse direction, the ink becomes unmixed! The demonstration seems to defy thermodynamics in that it appears that entropy decreases, but in actuality the reversible mixing is made possible by ensuring that the mixing/unmixing is done without turbulence. Read more about Reversible Fluid Mixing
Determine the capacitance of the human body as follows. Charge a person of unkown capacitance to 1000 volts. The person is subsequently connected (in parallel) to an external capacitor of known capacitance. The voltage measured across the capacitor combination allows one to determine the unknown capacitance of the person (typically between 180 — 200 pF). Read more about Capacitance of Human Body
The depth to which electromagnetic radiation can penetrate a conducting surface decreases as the conductivity and the oscillation frequency increase. This demo compares the skin depth of AM and FM radio frequencies, and shows just how small these distances are. Read more about Skin Depth
Light is refracted as it passes between two transparent materials of different refractive indices. If the materials are different, but the refractive indices are not, then the light rays are undeviated and the materials are optically indistinguishable. Read more about Disappearing Prism