Make: Technology on Your Time Volume 28

TOYS, TRICKS, AND TEASERS

By Donald Simanek, Recreational Physicist

The Slow Fall

Dropping a magnet through an aluminum tube takes longer than you’d think. Why?

GALILEO SHOWED THAT FALLING BODIES descend to earth with constant acceleration. Unsupported bodies, like stones, fall downward with an acceleration of about 32 ft/s² if air drag is negligible. Some bodies, like falling leaves, do fall more slowly, but usually not in a straight line.

So a body falling slowly downward in a straight path, with constant speed, is something we’re not used to seeing. One way to make this happen is to drop a solid body into a container of transparent, viscous ...