Magnetic braking of magnets sliding along a sloped aluminum surface

[foxpup]

We've had a few postings about sliding neo magnets on various aluminum surfaces.  I set up this topic to give that discussion a home.  It really does need its own thread.  Here are 3 youtube videos that are related to the subject

X00000013
May 19, 2009
http://www.youtube.com/watch?v=IqL3Byy9mDA

k4zep
May 19, 2009
http://www.youtube.com/watch?v=bElldY0TKJI

foxxpup
May 19, 2009
http://www.youtube.com/watch?v=edl5PsSyjG0

The idea is that when small neo magnets are caused to slide downhill on aluminum surfaces, they sometimes tumble off if started with one pole up and slide along slowly braking when the other pole is up.  X00000013 and foxxpup's videos demonstrate this effect k4zep's does not.

Please add your comments. :-)

[foxpup]

I was able to verify X00000013's demonstration.  Its a genuine phenomenon.

Personally, I think this phenomenon is a result of non-symetry in the magnetic properties of the neo magnets.   If the magnetic lines in the magnet on one pole were more concentrated than that of the other, the concentrated end might not be able to produce eddy currents in the aluminum as well (or better).   When the aluminum is at a shallow slope like what k4zep did, both ends would produce sliding and braking but as one progressively tries steeper slopes, one end will eventually demonstrate tumbling.  At steeper slopes the other end probably will too.  We need to do more tests.

[0c]

CLaNZeR
http://www.youtube.com/watch?v=XzmPAetbB08

Lumen0
http://www.youtube.com/watch?v=a0YCTwWvykw

TinselKoala
http://www.youtube.com/watch?v=iRtJsYVSswo

[TinselKoala]

It's remarkable.
Now I have observed that it is actually the LOWER or leading edge that appears to lift off first and the magnet begins to tumble backwards at least when it first comes off.

The orientation that doesn't come off will lift off at the leading edge too but not as much so it's more stable.

I think this actually indicates that the pole that comes off, is stronger because it gives more levitation from the eddys.

We may be inventing the mag-lev train, or something like that.

[TinselKoala]

@CLaNZeR:

ROTFL there at first when the one just wouldn't go...that was great, I feel a lot better now.

I think it's got to be the protective coating--or, is that perhaps genuine Al-clad, with that protection? The thin layer of pure Al over the alloyed sheet might make a diff.

Regardless, once you get the effect, please look on sideways, and see if you see what I see: the magnets lift off the plate from the lower, leading edge, first.