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A new pyramid-like shape always lands the same side up

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588 points robinhouston | 1 comments | 25 Jun 25 20:01 UTC | HN request time: 0.205s | source
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ChuckMcM ◴[25 Jun 25 21:09 UTC] No.44381861[source]▶
Worst D-4 ever! But more seriously, I wonder how closely you could get to an non-uniform mass polyhedra which had 'knife edge' type balance. Which is to say;

1) Construct a polyhedra with uneven weight distribution which is stable on exactly two faces.

2) Make one of those faces much more stable than the other, so if it is on the limited stability face and disturbed, it will switch to the high stability face.

A structure like that would be useful as a tamper detector.

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1. tlb ◴[26 Jun 25 08:29 UTC] No.44385378[source]▶
If you're not limited to a polyhedron, a thin rod standing on end does the job.

A rod would fall over with a big clatter and bounce a few times. I wonder if there's a bistable polyhedron where the transition would be smooth enough that it wouldn't bounce. The original gomboc seemed to have its CG change smoothly enough that it wouldn't bounce under normal gravity.