Answer to Riddle #84: Twiddled Bolts
An unusual puzzle this because your ability to answer depends on not your pure intelligence but your ability to visualize things in the abstract. I read this puzzle the other day, and I've been thinking of a way to explain it, I think I've come up with a good plan, let's see if you agree:
Consider the arrangement below:
It shows rather than two interlocking bolts, one bolt and a sort of specially designed thing with a singular thread in a circle around it.
It's reasonably easy to tell by intuition that given the orbital direction that the stud at the top (currently,) will move to the right.
Now consider the arrangement below...
The stud will also move to the right.
So if both are moving to the right, at the same speed, then there is no relative motion, (save the rotation,) at all.
Finally as the convincer I've included a video...
I know, I know, I twiddled the bolts in the opposite direction. Hopefully you can see that if the don't move relative to ach other when twiddled one way they wont when twiddled the other.
Puzzle comes from a book, My Best Mathematical Puzzles by Martin Gardner
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