DAY 91

Comment

What happens to X and how do the movements of X and Z compare?

Answer

Z makes 2 full turns anticlockwise.

Readers' methods

JH, Isle of Wight:
Each tooth on X makes contact twice with wheel W, so X makes two revolutions (anticlockwise).
If Z had direct contact with X, it would also make 2 revs, but clockwise; with Y between it and X, Z makes 2 revs anticlockwise.

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