Why are manhole covers round? - Marc Chamberland

2015-04-13

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Why are most manhole covers round? Sure it makes them easy to roll, and slide into place in any alignment. But there’s another, more compelling reason, involving a peculiar geometric property of circles and other shapes. Marc Chamberland explains curves of constant width and Barbier’s theorem.

Lesson by Marc Chamberland, animation by Pew36 Animation Studios.