Not many engineering students have an intuitive feel for the way capacitors, inductors, and resistors work together in viscously damped systems. To give them that kind of understanding, a professor at the Massachusetts Institute of Technology developed a lab curriculum that explains electrical components in terms of their mechanical corollaries: masses, springs, and dampers. But to make systems of mechanical and electrical components more analogous, the professor needed a zero-friction bearing. Using off-the-shelf roller bearings, even those with the lowest rolling frictions, would not work because even that small amount of friction masks the effects of damping.
Porous-media air bearings from New Way Air Bearings, Aston, Pa., fit the bill. Compressed air sent to the bearing disperses between the bearing and the surface through a carbon material with thousands, perhaps millions of holes. This even dispersion of air gives the bearings almost zero friction. The bearings are also relatively inexpensive yet durable enough to stand up to daily student use. They are also easy to use and align and can be quickly set up and broken down, a must for lab setups that change every week. The bearings also provide translation and rotation motion.