Flywheel -- Why does it reverse direction after spinning to a stop?

[CWatters]

I find it difficult to believe that a correctly designed heavy flywheel bearing would have enough friction recoil to make it rotate back much.

Edit: Can we see a video?

 

[sophiecentaur]

You could do some experiments, putting the wheel at various angles and letting it go to see where it goes.
Also, no one has suggested the possibility that this is an optical illusion. It could that there is no real reverse motion at all and that your brain is misinterpreting what you are seeing. There are many websites that show such illusions of motion. You can have an enjoyable Google session, finding them and seeing the effects.

This is a direct parallel with linear motion. Apart from a 'bounce' due to resilience in the system, you would hardly expect a mass that is brought to a halt, to move backwards after it comes to rest.

 

[jerromyjon]

I was going to make a video of my big old heavy door with really old hinges but as it tries to come to a stop it bounces back and forth a few times like a diminishing sine wave.

 

[jerromyjon]

I remember in younger days trying to "check" the balance factor of a bicycle wheel which did the same thing, I was able to make it not happen by loosening the bearings a bit.

 

[CWatters]

I've seen it with a door and a bike wheel but not a purpose designed flywheel.

 

[sophiecentaur]

It's just a matter of 'to bounce or not to bounce', surely. The general implication of the OP is wrong.

 

[Muti]

every rotating equipment need two things for smooth operation: balancing (simply mean, its mass must be homogeneous and alignment (simply mean, the two end which keep the fly wheel in proper place must be in a line) or else as DaveC told there would be wibbly-wobble (Vibrations). I think this set up is about function of fly wheel. Initially the work is done by string and weight due to gravity force, but when the string reach its end no further work can be done but fly wheel has stored energy due to its inertia... Ideally flywheel will give its energy in the form of torque in the same direction, but perhaps some one else give reason how it change its direction (may be due to third law of motion...)[PLAIN]https://www.physicsforums.com/members/davec426913.15808/[/PLAIN]