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

Post by kamel3d » Thu, Jun 26, 2025, 9:40 PM UTC

hinkley wrote: post #150

seniortaco wrote: post #144

I wouldn't really call this a "shape" since the highly manipulated center of mass is what is actually doing the work here. I would call this an object or rigid body.

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…

Post by Vvector » Thu, Jun 26, 2025, 10:31 PM UTC

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?

Post by Nition » Thu, Jun 26, 2025, 11:25 PM UTC

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?

Post by StimDeck » Fri, Jun 27, 2025, 2:38 AM UTC

ColinWright wrote: post #155

mzs wrote: post #153

Earlier quoted context omitted.

Your site is fine, thank you very much, I was not able to able to save it in the internet archive though: https://web.archive.org/save/https://www.solipsys.co.uk/ZimE... "Save Page Now could not capture this URL because it was unreachable. If the site is online, it may be blocking access from our service."

Interesting ... and baffling. I've simply exported that from the zim wiki, not doing anything special, so I have no idea why the internet archive would complain about it. And it's the other part of my site that people complain bitterly about: https://www.solipsys.co.uk/new/ColinsBlog.html?yf26hn

Post by Dylan16807 » Fri, Jun 27, 2025, 2:44 AM UTC

Nevermark wrote: post #95

kazinator wrote: post #56

Earlier quoted context omitted.

If the constraints are that an object has to be of uniform density, convex, and not containing any voids, then you cannot choose where its centre of mass will be, other than by changing it shape.

That isn't true. Look at the pictures. It has the same outer shape, that is all that is required for the geometry. And for center of mass, you set the positions for the bars, any variations in their thickness, then size and place the flat facet, in order to achieve the same center of mass as for a filled uniform density object of the same geometry. As the article says: > carefully calibrated center of mass Unless an…