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Re: [Phys-l] (no subject)



Friction is WAY more complicated than first year physics would have us believe.
The rule of thumb equation says that the friction force depends on the normal force times the 'coefriction of fiction' or some such term. ;-)
This would imply that if the weight of the object is the same - the area of contact doesn't matter.
Small area => large pressure but same force as a large area.

People who race for glory or for a living know well that first year physics doesn't work here.
They generally don't have much use for folks who QUOTE physics formulas either.

A better phenomenological view of friction is that it depends on how many 'atoms' of tire-onium can be mashed against the 'atoms' of street-onium.
It's these atoms grabbing hold of each other that lets the car push itself forward.


On Sep 26, 2008, at Sep 26(Fri) 2:56 , Connie Tyree wrote:

I have searched the archives and was unable to find an answer that is
satisfying. It is a drag racing inquiry...the back tires on drag cars
are very wide, soft and without tread. I understand that the width
allows for heat dissipation and the softness allows for better traction
with the track surface. What confuses me is the relationship between
friction and forward motion. Drag racing is all about acceleration. Is
the only reason that the tire is wide is for heat dissipation due to the
soft material? For argument sake, say a soft tire could be narrow and
dissipate heat equally well. Then, would a narrow tire propel the car
forward with the same force as a narrow tire?


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