rolling-ball
Round the square and back, turned
The contact point's path is a closed square of side 90 mm, and the little arrows are a marked point on the ball's surface, carried round by the rotation. The ball ends where it started and pointing somewhere else: 2.6425 radians against the 3.2400 the loop's area predicts. Nothing about the ball's own path is closed — the trace it makes on its own surface is not — and that is exactly why the orientation does not come back.
Wheels, and where they may not gowide
Where it is used
- The motion left over by going nowhere Wheels, and where they may not go
- How many wiggles Wheels, and where they may not go
- The ball that remembers where it has been Wheels, and where they may not go
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