4 ms·
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
by ChuckMcM 1y ago
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.
- deleted 1y ago[deleted]
- Evidlo 1y ago> A structure like that would be useful as a tamper detector. Why does it need to be a polyhedron?
- ChuckMcM 1y agoI was thinking exactly two stable states. Presumably you could have a sphere with the light end and heavy end having flats on them which might work as well. The tamper requirement I've worked with in the past needs strong guarantees about exactly two states[1] "not tampered" and "tampered". In any situation you'd need to ensure that the transition from one state to the other was always possible. That was where my mind went when thinking about the article. [1] The spec in question specifically did not allow for the situation of being in one state, and not being in that one state as the two states. Which had to do about traceability.
- nancysmith865 1y ago[flagged]
- cbsks 1y agoThe keyword is "mono-monostatic", and the Gömböc is an example of a non-polyhedra one: https://en.wikipedia.org/wiki/G%C3%B6mb%C3%B6c https://en.wikipedia.org/wiki/G%C3%B6mb%C3%B6c Here's a 21 sided mono-monostatic polyhedra: https://arxiv.org/pdf/2103.13727v2 https://arxiv.org/pdf/2103.13727v2
- ortusdux 1y agoYou jest, but I knew a DND player with a dice addicting that loved showing off his D-1 Mobius strip dice - https://www.awesomedice.com/products/awd101?variant=45578687807777 https://www.awesomedice.com/products/awd101?variant=45578687... For some reason he did not like my suggestion that he get a #1 billard ball.
- gerdesj 1y agoLove it - any sphere will do. A ping pong ball would be great - the DM/GM could throw it at a player for effect without braining them! (billiard)
- hammock 1y agoOr any mobius strip
- gerdesj 1y agoI think a spherical D1 is far more interesting than a Möbius strip in this case. Dn: after the Platonic solids, Dn generally has triangular facets and as n increases, the shape of the die tends towards a sphere made up of smaller and smaller triangular faces. A D20 is an icosahedron. I'm sure I remember a D30 and a D100. However, in the limit, as the faces tend to zero in area, you end up with a D1. Now do you get a D infinity just before a D1, when the limit is nearly but not quite reached or just a multi faceted thing with a lot of countable faces?
- zoky 1y ago> However, in the limit, as the faces tend to zero in area, you end up with a D1. Not really. You end up with a D-infinity, i.e. a sphere. A theoretical sphere thrown randomly onto a plane is going to end up with one single point, or face, touching the plane, and the point or face directly opposite that pointing up. Since in the real world we are incapable of distinguishing between infinitesimally small points, we might just declare them all to be part of the same single face, but from a mathematical perspective a collection of infinitely many points that are all equidistant from a central point in 3-dimensional space is a sphere.
- deleted 1y ago[deleted]
- gus_massa 1y agoA solid tall cone is quite similar to what you want. I guess it can be tweaked to get a polyhedra.
- MPSimmons 1y agoA weeble-wobble
- ChuckMcM 1y agoSo a cone sitting on its circular base is maximally stable, what position do you put the cone into that is both stable, and if it gets disturbed, even slightly, it reverts to sitting on its base?
- iainmerrick 1y agoI think you’re overthinking it. The tamper mechanism being proposed is just a thin straight stick standing on its end. Disturb it, it falls over.
- jayd16 1y agoI imagine a dowel that is easily tipped over fits your description but I must be missing something.
- schiffern 1y ago>useful as a tamper detector If anyone's actually looking for this, check out tilt and shock indicators made for fragile packages. https://www.uline.com/Cls_10/Damage-Indicators https://www.uline.com/Cls_10/Damage-Indicators https://www.youtube.com/watch?v=M9hHHt-S9kY https://www.youtube.com/watch?v=M9hHHt-S9kY
- p0w3n3d 1y agoThese shock watches and tilt watchers are quite expensive. I wonder how much must be the package worth to be feasible to use this kind of protection
- numb7rs 1y agoThese are pretty normal when shipping scientific equipment.
- bigDinosaur 1y agoIt may not just be monetary value. Shipping something that could be ruined by being thrown around (e.g. IIRC there were issues with covid-19 vaccine suspensions and sudden shocks ruining it) that just won't work may need this indicator even if the actual monetary value is otherwise low.
- Someone 1y agoDid you notice the column indicating number of items per box/carton? Shockwatch is $170 for 50 items, for example, and the label $75 for 200. Not dirt cheap, but I guess that’s because of the size of the market.
- p0w3n3d 1y agoyou're right, I missed it. 3.5usd does not seem so bad
- donw 1y agoFun fact: MythBusters used shock watches extensively when testing anything involving impact, because they were massively more reliable than any of their digital instrument.
- ErigmolCt 1y agoSort of like a mechanical binary state that passively "remembers" if it's been jostled
- tlb 1y agoIf 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.
- deleted 1y ago[deleted]