FUN: Engineering Folly

Science  25 Apr 2003:
Vol. 300, Issue 5619, pp. 557
DOI: 10.1126/science.300.5619.557a

The Museum of Unworkable Devices gives students an entertaining way to test their physics know-how. The mechanisms depicted here are all real designs, but they would never work because their creators misunderstood or overlooked crucial physical principles.

Curator Donald Simanek, an emeritus professor of physics at Lock Haven University in Pennsylvania, gathered many of the designs from history books and received others from readers—some of whom believed their submissions were sound. Using basic physics, he clearly explains fatal flaws with contraptions such as this variant of the perpetual motion machine. The north poles of the outer ring of magnets all face inward, and by repelling the north pole of the central magnet and attracting its south pole, they supposedly create an ever-turning rotor. The main fault is that the shield surrounding the central magnet is subjected to forces equal and opposite to the forces on the magnet, canceling out the rotation. The design flaws can be subtle, and Simanek leaves several examples for readers to figure out.∼dsimanek/museum/unwork.htm

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