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Re: pic: Magnetic traction
The steel pole is ferromagnetic, so a magnet will exert a pull toward it, aiding traction of the wheel(s).
Steel is also an electrical conductor, so electric potentials induced in it as a magnet moves will drive the flow of circulating current. Magnetic fields due to the circulating current will interact with those due to the magnet, developing a drag force that opposes the magnet's motion. So the steel pole acts as a brake on the magnet -- even if they don't touch.
__________________
Richard Wallace
Mentor since 2011 for FRC 3620 Average Joes (St. Joseph, Michigan)
Mentor 2002-10 for FRC 931 Perpetual Chaos (St. Louis, Missouri)
 since 2003
I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
(Cosmic Religion : With Other Opinions and Aphorisms (1931) by Albert Einstein, p. 97)
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