My mind is blown, someone please explain this!

[DirectorGunner]

I stumbled across this when bored browsing kickstarter tonight
https://www.kickstarter.com/projects/altdynamic/orbiform-a-mathematically-perfect-solid-of-constan/description
What in the find voodoo?
The shape makes no sense to roll like a sphere in keeping an object above it level...
I feel like I'm being deceived when I watch this.

Someone, anyone, scientist, explain!

 

[Metal-Muffin]

It’s just a drunk sphere.

 

[Talonsbane]

When you look at the profile of it, it greatly resembles the shape of the internal portion of a Rotary engine to me. It is similar to a nearly spherical top as far as I can tell. I would be more interested if they could take this modified cone design & shift it from 1 actual pinnacle opposed to a firm ridge ring into more of a modified triangular prism with 4 equal pinnacles while retaining the same qualities, abilities & principles of motion.

 

[Bruce]

I feel like I'm being deceived when I watch this.

you are deceived my friend :) ... it doesn't roll like a sphere - it changes connection point erratically .. but as a math joke it is totally fine and valid :)

 

[Bruce]

Here is some video of main in China who thought it is the same :)))

View: https://youtu.be/ebRI4kFmR7U?t=9

 

[Printimus]

its how Rotary engines work too.

 

[DirectorGunner]

I'm still confused lol

 

[zeddie]

here's a video:

View: https://www.youtube.com/watch?v=2eUWT9cI23o

 

[Bruce]

The shape makes no sense to roll like a sphere in keeping an object above it level...

Hey ... now I believe I finally figured out how to solve your confusion in a simple way. Those shapes actually ARE spheres ... to be precise combinations of some pieces of some spheres :)

 

[Thalstan]

The key is, the center moves as well. Scroll down a little under the video and you will see it. As mentioned before, it’s how the rotary engine works.

 

[Vavrik]

The trick is, all of the points on the radius are equidistant their opposite side, just like a sphere - so, it can roll like a ball. Yes there are rotary engine designs built on this principle (the Wankel engine), but not all rotary engines do.

 

[NaffNaffBobFace]

If you likes those shapes you may like this one: The Gomboc.

it's a shape with just one point of equilibrium. No matter what side you put it down on, it will always, always return to its rest point, with no added weights or tricks.

If the video went on long enough it would stop rocking, and it would always come back to that point even if it were turned upside down, placed on its side, on its end etc.

 

[Jolly_Green_Giant]

 

[Bruce]

If you likes those shapes you may like this one: The Gomboc.
it's a shape with just one point of equilibrium. No matter what side you put it down on, it will always, always return to its rest point, with no added weights or tricks.

very interesting shape indeed, just a small correction here - after reading some stuff about it, it looks like gomboc is mono-monostatic shape (i.e. it is a shape with exactly one stable and exactly one unstable point of quilibrium) .. there are tons of other shapes with exactly one stable and multiple unstable points :)

 

[Bruce]

hey ... where did you get the video of young derek ?

 

[DirectorGunner]

It's still confusing.. so it's built out of intersecting circles.. okay got that... but ....... something still isn't processing about this in my brain lol... I guess I'm trying to process motion + center mass (or whatever it's called for the center of a moving object which for spheres is constant but for other objects isn't)

hey ... where did you get the video of young derek ?

lol that needs to go viral as a new DS meme!

 

[Jolly_Green_Giant]

hey ... where did you get the video of young derek ?

I burst out in laughter over this. Thanks :P

 

[Vavrik]

The trick to the gomboc is, any rotation from the point of stability causes the center of mass to become offset from the center of rotation. there are tons of shapes indeed, but at least there is a commercial application. They're not just curiosities. The hull of a self-righting displacement boat or ship, is usually in the form of a gomboc.

It's still confusing.. so it's built out of intersecting circles.. okay got that... but ....... something still isn't processing about this in my brain lol... I guess I'm trying to process motion + center mass

Well, roleaux polygons (these aren't called Obiform) work because if you roll them, the side exactly opposite the point of contact is always the same distance from the point of contact. Make two 2d identical roleaux polygons out of cardboard, and place them between two rulers. You can see this at work a little better and play with orientations to see if it makes any difference.

It doesn't really have anything to do with the center of mass, it's the dimensional change as you go around the polygon.

By the way, you can have roleaux polygons made with any odd number of sides over 1, so 3, 5, 7 9 etc.

 

[DirectorGunner]

It doesn't really have anything to do with the center of mass, it's the dimensional change as you go around the polygon.

By the way, you can have roleaux polygons made with any odd number of sides over 1, so 3, 5, 7 9 etc.

Does at any point the level / distance of glass to the table, with these things underneath the glass when rolling around, change?
If there's no change... yet rolling surfaces that are not spheres... it's mind boggling...
I'd imagine however that resistance is not the same during movement?.... which is why I assume bearings are spheres, not these things.

And if such things happen in 3D space... how much mind boggling are things that happen in 4th and 5th dimensions relative to us.

Assuming, there is an efficiency difference between using spheres and these objects... wonder how that could be used in some situations at an advantage.


btw.. I come from a construction background.. I built things... round is round and not round is not round... round stuff rolls, not so round stuff doesn't roll as good as round stuff... so was super confusing seeing this.

 

[Vavrik]

Does at any point the level / distance of glass to the table, with these things underneath the glass when rolling around, change?
If there's no change... yet rolling surfaces that are not spheres... it's mind boggling...
I'd imagine however that resistance is not the same during movement?.... which is why I assume bearings are spheres, not these things.

And if such things happen in 3D space... how much mind boggling are things that happen in 4th and 5th dimensions relative to us.

Assuming, there is an efficiency difference between using spheres and these objects... wonder how that could be used in some situations at an advantage.


btw.. I come from a construction background.. I built things... round is round and not round is not round... round stuff rolls, not so round stuff doesn't roll as good as round stuff... so was super confusing seeing this.

Good questions. I did it again by the way, it's reuleaux polygon.
The distance to the glass table does not change. You could describe a perfect sphere as a 3d reuleaux polygon with an infinite number of sides. There's another property though that makes the 2d kind especially useful (and answers another of your questions). Watch what happens to the center of rotation as they move. It describes a sine wave. An armature attached there will move in and out, just like a piston on a crank shaft - only you don't need a crank shaft or all the mechanical assemblies that go with them.

There is no efficiency loss in the motion, except they are harder to make than spheres, so expensive.