Unbelievable Spinning Disk
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42 
2. banzemanga 2 years ago
Someone got to explain that to me. 
At first i thought the disk's spinning increased because the disk and the magnets were magnets with the same polarity. But at the end, it showed that the disk stop spinning touching the surface meaning that they are not magnets of the same polarity. Therefore, my hypothesis is incorrect.
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4. Comment rated too low. Show this comment Jahoo 2 years ago
Rotating magnet in the plate, same concept that you use in chemistry when you need to keep a mixture in motion.
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5. BreakIsBetter 2 years ago
There's no magnetism at work here. It's just a finely machined metal disc on a slightly concave mirror. Nothing but gravity and the momentum imparted initially to the disc. There are no (or very little) imperfections between the edge of the disc and the surface that would normally act as an energy sink, so you get a nice, long spin with an amazing increase in frequency towards the end.
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I would have liked to see some markings on the disk to see its circular motion around its center.
P.S. #5 is correct
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As #5 said, no magnetism. Every coin does this, only it stops sooner. The rotation is not speeding up. At the end, the actual rotation speed is almost zero. Only the wobble frequency is increasing because when the angle decreases, the axis of rotation and the axis of wobble (precession) are almost parallel and fast opposite rotations about these two axes cancel out into slow actual rotation of the disk.
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13. schlafanzyk 2 years ago
It's the same thing that happens when you spin a coin on a glass/mirror surface, just slower due to the larger mass and size of the disk.
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I love how at the end it stops so cleanly and definitely. The end also reminds me of the film Cube (1997) for some reason.
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Unless the surface upon which the disk is spinning is concave, due to the disk's gravitation to the center, magnets are certainly involved.
(138 votes)
+7
1. Matteo 2 years ago
zero friction