Did you know that, at a certain point on a moving wheel... there's no motion? Did you know that, at a certain point on a moving wheel... there's no motion? I mean, kinda... it's all relative, right?

Shown below is an animation of the motion of A and B as seen by a stationary observer. The paths of A and B are straight, as expected, with the speed of B increasing in time. View of B as seen by an ...

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The mechanics of friction may seem the stuff of high-school physics, but only now are some aspects of the problem being understood. A spinning coin is the subject of a new exploration of frictional ...