Euler’s Disk! Incredible Physics or Black Magic?

[robtowen]

You know it's a little disturbing to find an auto mechanic that takes pleasure in a toy that mimics the sound of a vehicles motor seizing up due to a lack of motor oil.

[aesouris]

This is one of those demonstrations of physics that just makes me smile. No practicality as-is, just fun.

[garyhead]

The incredibly low friction of the toy will be offset by the increased friction between you and your wife if you play with that thing too often.

[TyrantJD]

Objects in motion tend to stay in motion unless acted on by a force. In this case there's little energy lost, due to lower friction. Smooth surfaces plus for most of the run it's only riding small sections of the edge of the disk. Such a fun gizmo.

[RainmanRaysRepairs]

I thought about cutting it off right before it stops, but I don’t have it in me to be cruel.

[strawmangaming]

When I worked in a parts warehouse, we used to do this with fly wheels and the bigger brake discs if they were junked. Worth a try next time you're in the shop.

[Justice-Seeker]

I suspect the camera and subsequent compression messed with the visual effect that you'd get if watching in person. Apparently the disk will appear to float.

[fredproctor]

Sounds like one of those toys that you buy your niece or nephew so they can drive their parents up the wall while you sit back and laugh your a$$ off.

[ticdelarue]

It sounds like an old Hit and Miss engine without the exhaust sound

[AltoonaYourPiano]

I love how it starts out sounding like Muttley from Wacky Races before spinning mindblowingly fast. I managed to get it to spin for 2 minutes once, always fun to try to see your best time.

[stephenruhl]

When Richard Feynman was at Cornell, he observed a dinner plate fly across the cafeteria and the same spinning phenomenon .
Currious about the mathematics, he went back to Newtons equasions, solved them, brought them into quatum mechanics, created Quantum
ElectroDynamics (QED) (over simplified explaiation) and won a Nobel Prize.

[cup_and_cone]

Reminds me of the store in the mall from the 1990's called Natural Wonders...had all kinds of cool science gadgets like this.

[jimmyhorton]

Dang, now I gotta get a new haircut, because my head just exploded! Oh, by the way, saw a truck in traffic today you would have liked. Had custom letters on the tailgate that said “ Silveraydo “ on one side and “ Redneck Edition “ on the other. Tried to get a picture, but I wasn’t fast enough. Have a good weekend.

[scottminer]

I was first introduced to this as a young firefighter in his first station except they used Corning dinner plates on a polished concrete floor. The sound was amazing. The thick cast iron sewer lid was almost unbearable.

[MN_Kevin_Hill_]

Pretty cool toy for sure. Now to harness the power into an engine of some sort.

[martinaudet]

I've putted on some greens like that. Like putting on chrome.

[simonilett]

The same effect can be seen by spinning a coin on it's edge on a flat shiney suface, but the coin won't spin for nearly as long as this device until it eventually falls flat and stops.
Both outcomes are directly related to the mass of the spinning object and the coefficiency of friction.
However, this may also be a simple con, with a spinning magnetic field generated below the mirror in this device to keep the disc spinning longer.
Once the magnetic field can no longer overcome the force of gravity pulling downward and the ever increasing friction on the spinning disc, the disc eventually falls flat and stops spinning.
There are never any free meals with physics.🤣👍🇦🇺

[daddykozak]

i am forever keeping this in a separate playlist away from everything called "serotonin"

[rhadden]

I wish I had one of these, all I have is my Fitbit to play with.

[joeythedime]

Gravitational energy is transferred to kinetic energy of the falling object.