Re: Rolling, Static, and Kinetic Friction

[David Dockstader <DRDOCK00@UKCC.UKY.EDU>]

On Sun, 14 Jul 96 17:22:19 EDT Emilio O. Roxin said:
> ... friction at rest cannot overcome the tendency to slide, hence it starts
> sliding. But the very moment it slides, the friction coefficient
> increases and stops the motion. This poor object doesn't know what
> to do: it is neither allowed to rest nor to move!

Exactly!  This is what keeps race car drivers alive.  If when the tires
started to slide mu suddenly dropped, the car would slide into the wall.
Lucky for the driver, mu actually increases up to a point and so a skillful
driver        can push somewhat beyond  the point where the tires start to
slip.

We're used to the case where you tilt the incline until the block starts to
slide, then decrease the angle to maintain a constant velocity.  The race car
driver tilts the incline until his car starts to slide and then further
increases the incline to maintain a constant velocity.  I think to get this to
work in the lab we need very soft rubber and a very rough surface.  The cast
iron on teflon sounds interesting.  I wonder were I can get some scrap teflon.