A question about a visual effect on a rotating prism

[Breo]

Hello folks,

I was playing with a rectangular prism 4x4x3 (almost a cube) and I was giving him a rotating movement with the hand over the table so I could see a visual effect I have seen many times in my life and now I remembered to ask about it.

So when I give to it an impulse and it start to rotate I can see very well defined smooth edges, well really a circular edge, with the actual vertex diffusal. In other words, like if it was a cylinder rotating with almost invisible vertex and edges.

I understand that we see the only constant points in the rotation move, this is the incircle (or in-crylinder) of the prism. The vertex only passes in discrete times over the same points so that is why it becomes diffusal.

However I want to know the mathematical/physical explanation of this.

Thank you in advance.

 

[Danger]

I'm not quite sure what you mean. If I understand you correctly, what you are asking about is a function of the physiology of the human visual system rather than an intrinsic property of the prism.

 

[A.T.]

Over I want to know the mathematical/physical explanation of this.

Haven't you explained it already? What exactly is still unclear? You see the cylinder where there always is a part of the spinning prism. The rest is a mix of prism and background.

Here is a related puzzle, based on spinning stuff fast:

 

[Danger]

A.T., you had better be prepared to provide me the solution to that...

 

[Breo]

Haven't you explained it already? What exactly is still unclear? You see the cylinder where there always is a part of the spinning prism. The rest is a mix of prism and background.

Here is a related puzzle, based on spinning stuff fast:

I suppose... but only in a very lay way... There must be mathematics behind... :/

I am sorry for my language barriers :P