NON-DELIVERY of: Re: Rolling, Static, and Kinetic Friction

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  From:     phys-l@atlantis.cc.uwf.edu at internet@CCMNRC
  Date:     07-14-96 07:28:00 PM
  Subject:  Re: Rolling, Static, and Kinetic Friction



> Assume an object resting on a plane of inclination alpha.Let alpha
> start being zero and increase gradually. At some critical angle,
> the 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!
>      Regards     Emilio
A neat demonstration is to place a toy train engine on a track as you
state in the above paragraph.  When the angle is positioned just at the
point where the engine will slide down the incline, try to move the
electrical engine up the incline and you will find the engine will begin
to slide down the incline as soon as the wheels begin to turn.  It is a
bit difficult to get the engine right at this point.  The track needs to
be very clean and parallel to the supporting incline.

Lowell Herr