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Deriving the amplitude of a coulomb (dry friction) damped spring

If by dry friction you mean a force that is constant with respect to velocity and points in a direction opposite to the velocity, then finding a closed form solution to your problem will be extremely ...
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Smallest possible rolling resistance

You never want the outer race or the inner race to slip against anything except for the balls. Technically you don't want it balls to slip either but if slip has to happen anywhere, you want it to be ...
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Smallest possible rolling resistance

What causes the rolling friction is the deformation of the material Figure source: electronicsteacher.com So if you need to have reduced friction you would need surfaces that are not easily ...
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Force Required to Keep Ball Rolling

Friction does work to remove energy from the system that is $W=\int F(t) |v|dt$. If you treat F(t) as a constant so it becomes W=Fd, even when it's not really constant that should give you an average ...
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Is there any material that has a higher kinetic friction than static friction?

The numbers for static and kinetic friction in aluminum-on-aluminum interactions, cited by @albseb back in 2016, are unreliable. Strangely though, they're the only published values. I'm a physics ...
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Collecting a released rope with a proper speed

This is similar to a low-tension rewinder application used for filaments and films / webs. The simplest solution would be to run a rewinder motor in constant torque mode. This could be achieved with a ...
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Collecting a released rope with a proper speed

Simplest method: torque-limiting clutch. I have one on my electric screwdriver. Less simple but even finer control: torque sensor with feedback to the motor winding speed.

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