Originally Posted by
v1c10us
Okay, if this doesn't shut you guys Up i'll have to get really technical.
"Occasionally it is maintained that µ is always < 1. While in most relevant applications this is true, having a µ > 1 merely implies that the force required to slide an object along the surface is greater than the normal force of the surface on the object. For example, silicone rubber or acrylic rubber coated surfaces have a coefficient of friction that can be substantially larger than 1."
This includes tires, which means if tires were made of wood what you are saying is correct, but since they are not, it is incorrect because µ is greater than 1 not less than 1
Also you have to take into account that the normal force is being varied by the brakes, its not constant because the brakes are not an ON OFF machine;
Since the friction force is a product of the kinetic friction and the normal force. Since the FULL normal force is being applied when the brakes are locked up the frictional force is greater than when the normal force is not being fully applied in order to keep the tires rolling, this reduction reduces the elements in the equation and results in a lower product, or in this case a lower frictional force.
edit: it would be different if the brakes were always fully applied, you would have equal forces at work, but due to the increased force and the decreased sliding friction it equates to the sliding friction of the tire being slightly greater than the rolling friction.
You also have to take into account the maximum static friction the 2 materials can attain, but thats not really relevent because its not very much.
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