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I've read a bit about the "normal force" modeling of friction here. I gather that it isn't a full picture, but a decent approximation, if it fits the needs of what you are trying to model.

It mentions that there's a static friction and a kinetic friction where the static friction is the amount of force that needs to be overcome before an object will begin moving, and then the kinetic friction specifies how much force you need to apply to keep the object moving.

For the case of a ball rolling or a wheel spinning, I know that a little bit of force will cause it to roll, while applying a lot of force will cause it to "slip" and lose contact / friction with the ground and start spinning.

In this case, is it the static friction that determines how much force you can apply to a wheel or a ball before it starts to slip, and then it's the kinetic friction that determines how it acts when it is slipping?

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  • \$\begingroup\$ Rolling resistance determines how much force is needed to keep it rolling at the same speed. \$\endgroup\$ – ratchet freak Jan 11 '17 at 9:16
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TL;DR: Static friction.


The amount of force needed to make the ball "slip" is determined by static friction.

Actually it's not too hard to understand: When the ball is not "slipping", in each infinitesimal moment of time the point of it which touches the surface doesn't move relative to it.

If the ball is "slipping", the dynamic friction determines how quickly it's angular velocity is being converted to linear velocity.

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