Look at this experiment: Why roll the balls after the collision back to each other? Are they magnetic?
Look at the sky reflection, right when they collide.Danger said:I can't really see the spin.
The density distribution seems symmetrical, given how uniformly they roll.zoki85 said:Is it certain that balls/spheres are made homogeneous ?
Okay, I've got it now. When I first looked at it, that arrow thingie just didn't quite register in my brain. It took half a dozen more viewings before it did. (I saw it; I just couldn't figure out what it was doing.) Maybe temporal dyslexia affects visual things as well as spoken ones.A.T. said:Look at the sky reflection, right when they collide.
Maybe there's sidespin as well, so they weren't in a visible spot earlier. Originally, once I realized that they were arrows, I suspected that they might have been digitally added to indicate spin, but that doesn't seem to be the case.RonL said:I'm not sure why I only saw the arrows appear one time ?
Because they cross the upper bright part only one time. But you see them also at 0:17 on the left ball, in the lower right part.RonL said:I'm not sure why I only saw the arrows appear one time ?
Thanks, yes:)A.T. said:Because they cross the upper bright part only one time. But you see them also at 0:17 on the left ball, in the lower right part.
I just read the OP's "are they magnetic?", watched once, then read your spoiler, then watched again and it all made sense.DaveC426913 said:Did no one read my spoiler? It describes the arrows.
I read it, and once I actually realized that they were physically present as opposed to CGI it made sense.DaveC426913 said:Did no one read my spoiler? It describes the arrows.
I didn't get it at first either, just click and drag the mouse like you are selecting text to copy or quote.RonL said:I can't understand what highlight to read, is supposed to do ?
Thanks, I finally figured it out :) I'm pretty simple minded when it comes to finding text that's not visible. :Djerromyjon said:I didn't get it at first either, just click and drag the mouse like you are selecting text to copy or quote.
DaveC426913 said:Spoiler! Highliight to read:
The balls are quite dense. They are running on rails, which means they are rotating much faster than their movement would indicate. There's a lot of angular momentum stored.
That angular momentum is not lost when they collide and bounce off each other. In effect, as they move apart, they are "skidding" - they've lost traction, but are still rotating. Eventually the rotation gains traction on the rails and the spheres accelerate toward each other again.
Reviewing the video again, I can see confirmation that I am right. The balls are not perfect; there is an arrow marked on each of them which shows how they are rotating. You can see the arrows in the closeup (as a matter of fact, you can juuuust catch them at the start of the closeup - at 0:19 juuuuust as they disappear into the black reflection at the bottom.) They are rotating the same direction both before and after the collision.