Magnetic braking of magnets sliding along a sloped aluminum surface

[TinselKoala]

obviously... 
the point is, if you 'play' with magnets, even a little, you stumble upon this (not new) phenom...
if you didn't, well, you're not very creative, imaginative or deductive.

Hmmm--an incorrect assumption, and we all know what happens when you "assume" something. I have shown this phenomenon to several people who have demonstrated their creativity, imagination and logical ability over and over again, and they are amazed by it. So at least some creative imaginatory clear thinkers, who have played with magnets a lot haven't noticed it before.
Therefore, as so often seems to happen, you are wrong, again.

If it's such an ordinary thing, why is it capturing the imagination of those who have them?

And if you've known about it all along, surely you've documented your prior knowledge with a video, a post on a forum somewhere, even a lab notebook page. Somewhere. Surely.

[TinselKoala]

Thanks for the info.

One more quick question:

Do you think there´s a chance the seperation force could somehow be seperated from the lenz braking force, say with lamination techniques etc? I suppose a better way of asking is: do you think the (braking/seperation) ratio could be varied with the aim of minimising braking and possibly making the seperation force the strongest?

Well, as I see it the repulsion is a consequence of the whole Lenz/eddy thing. I mean, moving magnet induces circular currents in the conductor, orthogonal to the motion of the magnet. The current curls orthogonally to the field of the magnet.  Barring relativistic effects, the motion of the magnet should not lead or lag the current circles--disk really, I suppose. The circulating current is accompanied by its own orthogonal magnetic field which is in opposition to the field of the magnet. It is the resistance to the current in the current disk in the slide material that produces the drag force, and it is the repulsion of that current's mag field to the magnet's field that lifts the magnet (or conversely the conductor).
All that seems well understood, I think. And it would seem that the only way to separate the forces of drag and lift would be, well, to get rid of the electrical resistance in the disk. I wonder how we could do that...No, wait, I know...

But what I do not know is why the effect we are talking about in this thread is asymmetric WRT polarity of the magnet. Is that in Wilby's or Abba's posts? Because if it is, I don't see it.
http://www.youtube.com/watch?v=JRby1Wilv-Q

[0c]

Is there anybody out there with some simulation software that might show this effect?

[0c]

It is the resistance to the current in the current disk in the slide material that produces the drag force,

Actually, I think the drag increases with less resistance. The more electrically conductive the material, the greater the current flow, the greater the effect.

[TinselKoala]

Actually, I think the drag increases with less resistance. The more electrically conductive the material, the greater the current flow, the greater the effect.

I don't believe I said anything about the nature of the relationship. The drag is caused by and related to the resistance; it represents the energy lost in Joule heating of the slide. But sure, the more current flow, the more Joule heating--even in the same resistance. Move faster, you get more voltage. Same resistance, the slide's the same material still. So you get more current, hence more drag. The drag force goes up with relative velocity even when the resistance remains the same. But in thicker material there is more conductor cutting flux; less bulk resistance overall, but way more current--hence more drag. The relationship isn't as simple as you make it out to be.
But it really isn't current flowing around in a ring like a circle around the location of the magnet, though, I don't think. Isn't it more like a disk, centered on the magnet's position, of tiny tight vortices, where the conduction electrons are whirling around the field force lines? So why don't their accompanying fields just cancel the original field by pushing it out, thus killing the whole effect, thus allowing the effect to begin, thus...
Uh, oh. Better go freshen the beverage.

But anyway I don't think the bulk resistance is effective against eddys in the same way that resistance to a current in a wire is, for example.

http://www.magnet.fsu.edu/education/tutorials/java/foucaultdisk/index.html