Just to add a couple over "experimental" considerations to the ideas
on friction. Principally, the "traction" is a more appropriate term in the
case of "dynamic friction," ie race cars etc.
Think about the case of a motor bike (in my case a ZZR1100). They would
not go round a corner if static friction was the only thing holding
them on the road. I believe that the others are right. One important
aspect is the removal of very small pieces of rubber, or layers. What
really helps a motorbike is that the contact area is being continously
replaced by a fresh area. That is what keeps it on the road far beyond the
point that static friction alone would be able to achieve.
I guess the short message here is the vital importants of the dynamics
of the tractional processes and the fact that the contact areas are being
replaced all the time.
Sandy
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Sandy Yates / Area de Mecanica de Fluidos / Centro Politecnico Superior
Maria de Luna, 3 / 50015 ZARAGOZA. SPAIN
Phone: Spain (76) 761000 ext 5045. Fax: Spain (76) 761882
Email: sandy@ideafix.cps.unizar.es