Why a tossed tennis racket flips: the intermediate axis theorem
30seconds
Spin a tennis racket about its handle or its face and it flies cleanly. Spin it about the third axis and it flips, even in orbit where nothing pushes on it.
Every solid has three special axes: easy, hard, and in between. Spin about the easy or hard one and wobbles stay small. Spin about the middle one and any tiny wobble grows until the object turns over, again and again. Try it with the block.
Deep dive · 3 min
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