Puzzles

This is a collection of puzzles, mostly about physics, that yield to simple, insightful solutions. I have tried to avoid any that require calculus. Some of these are classics with a history that goes back to the 19th century or earlier. Some I invented myself.

Some have answers, but not all answer discussions are complete. Puzzles with asterisks are essentially finished. Those without links are in development, not yet written. Those with dates have appeared in the SPS Obeserver.