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

quantamagazine.org

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

#171

Post by degamad »

kamel3d wrote: post #161
hinkley wrote: post #150

Earlier quoted context omitted.

It’s both. To work you need a polyhedron constructed of a series of polygons, here triangles, and one of those triangles has to have its center of mass outside the base of the object in all orientations. Otherwise the weight will pin it down instead of tilt it over. That’s why in the one orientation it tips back before tipping sideways: the center of mass is inside the footprint of right edge of the tetrahedron but n…

A ball that has a weight attached to one point from the inside would always land on that side, it's the same thing, right?

Correct - we knew we could do that with balls, but can you do it with a pyramid? It initially seems like there would always be at least two stable surfaces for a pyramid, but this group managed to figure out how to do it with only one stable surface.

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

#173

Post by lloeki »

stavros wrote: post #126
riffraff wrote: post #124

Earlier quoted context omitted.

Lenticoidal, I guess? I.e. remove the outer face of the cilinder by making the faces curved

Yeah, that was my thought as well, but that's also basically a D3 with a really small third edge, in practice. I was wondering whether there's some clever shape that actually is a D2, though maybe that's a Möbius strip in reality.

> what did the D2 look like

> though maybe that's a Möbius strip in reality.

You're close, it looks like a failed attempt at doing a möbius ring.

https://www.awesomedice.com/products/the-d1

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

#174

Post by schiffern »

p0w3n3d wrote: post #107
schiffern wrote: post #99

Earlier quoted context omitted.

>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.youtube.com/watch?v=M9hHHt-S9kY

These 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

Link wasn't a storefront or brand recommendation, just a handy overview for people unfamiliar with the category.

The SpotSee/ShockWatch brand does seem to be more expensive (almost $4 per device), but they have interesting variants like shock-triggered RFIDs.[0] Otherwise you can find competitor products at roughly half the price.[1]

[0] https://shop.spotsee.io/impact_indicators

[1] https://impactograph.com/product/shock-indicator-labels/

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

#175

Post by p0w3n3d »

Someone wrote: post #112
p0w3n3d wrote: post #107

Earlier quoted context omitted.

These 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

Did 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.

you're right, I missed it. 3.5usd does not seem so bad
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