physics discrepency

[kilipo4]

OK, according to my physics class a couple years ago, the force of friction is equal to the normal force between the two objects times the coefficient of friction.

So, why do wider tires give you better traction? The normal force is the same (weight of car X 9.81) and the coefficient of friction is the same because you're using the same two materials. No where in the equation does it mention the contact surface.

I know physics isn't wrong and I know more contact surface on tires = more traction. So, where is my mental discrepency?

Thanks for indulging me,Cliff

[Exar-Kun]

K is gonna ream me for trying to answer this without know for sure, but here we go:I think that the surface area(or contact area) affects the ammount of friction something can cause. Take for example a small sanding block, and a large one. put the SAME ammount of weight on each block, and push it forward. the larger area sanding block will be harder to push.

I dont remember what the equasion is for this, but Im pretty sure it involves surface area(or area of contact)...

-chetK, I know you are the one to answer this, just dont bend me over too much.

[kilipo4]

ya...i thought all that through. think about it. take that larger sanding block. say its got twice the surface area as the smaller one. so...imagine cutting it in half. you would have two of the smaller ones each with half the weight. so you end up with half the weight on the same surface area, times two. that comes out as the same force of friction.

Next.

-Cliff

[Exar-Kun]

I stand corrected. thanks K!-chet

[kilipo4]

Thanks K. I knew there was a reason, just couldn't put my finger on it.

-Cliff