
#1
Dec2312, 11:01 PM

P: 77

I'd read that friction is independent of the surface area of the bodies in contact. But somewhere in the internet I found that this explanation was just a good approximation and that friction actually depends on area. Can anyone explain a bit more on this?




#2
Dec2412, 12:51 AM

P: 746

Just look at the equations for the force of friction..nowhere is the surface area of the object included




#3
Dec2412, 06:10 AM

P: 77

You can look @ http://zebu.uoregon.edu/1999/ph161/friction.html
and there you will find written friction is nearly or mostly independent of surface area. That must mean there is something more to it than just normal force and a constant. 



#4
Dec2412, 09:06 AM

Engineering
Sci Advisor
HW Helper
Thanks
P: 6,386

How friction depends on surface area...Some students seem to get the wrong idea that Coulomb's "law" of friction is the same sort of law as Newton's "law" of gravity or the ideal gas "laws". It isn't. More complicated models of friction include the flexibility of the objects that are in contact, and possibly the atomic structure of the materials as well, but the only practical way to use those models is in a computer simulation, not setting up and solving problems by hand. 



#5
Dec2412, 09:42 PM

P: 77

Just asking, would it be possible to derive the simple : friction = μN expression from Coulomb's law for electric charges?



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