Look carefully at this video of a tangled light blue ribbon. The
tangle was originally made by the
Twisting and Turning
method, but in the video it is manipulated
in a number of ways. Can you explain what is happening? Can you see
some properties of this tangle that the video is trying to
demonstrate? Do you think these properties hold for any tangle?
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Can you work out the fraction associated with the tangle in the
video? You'll need to decide on an initial configuration and
orientation, so let's say that:
- the zero tangle would have the two ropes parallel to the green
- twisting always occurs on the green axis in the direction of
the green arrow;
- turns are a quarter turn about the blue axis in the direction
of its arrow.