Eomer said:
Now, I dropped out of engineering after my first year, but I still remember my statics and dynamics pretty well. To me, if two materials are bonded together, using a friction equation is pointless. There is no normal force, there is no friction, the two things are bonded together. At that point it"s the strength of the materials that matters. Friction is irrelevant. At that point you"d be looking at torsion and sheer and all that happy crappy.
Aye, you"re right. Thus my initial statement that mu is always less than or equal to one, but it
couldbe looked at like Frawdo points out.
Like I said, I can"t think of an instance where it would be beneficial, but if some physicist pointed it out, somewhere out there on the web, for Frawdo to bring it here then I would assume that there is some sort of situation where it"s beneficial to use that perspective.
/shrug
Physics is all about mental backflips and different perspectives. At this point, I wouldn"t say that I"m enough of an expert to dismiss any perspective at all as completely useless. I"d say that it will be a long time before I can do that.
GraysonCarlyle said:
How does it come out as infinite on a bonded object? u = Ff/N
Actually:
F = ufcos(T), where T is the angle between the surface and the force, f, in question, u is mu (too lazy to copy/paste it), and F is force of friction.
Of course, this is where the normal force, N, is:
N = fcos(T)
Thus, we have:
u = fcos(T)/F
Thus, if u is inifite, to me that would imply that f is infinite. Therefore, for two bonded objects to have an infinite friction coeff, the one object they make has to be perfectly resistant to distortion; at least relative to the forces involved.
So far as where this *might* be useful, from what I understand (and I know squat about differential geometry yet), it"s useful to know what shape an object is homeomorphic to (what type of shape you can distort it into).
For example, a coffee cup is homeomorphic toward a taurus (if it"s made of clay, then the most basic shape the clay could be molded into from the coffee cup shape without tearing it is a taurus). A taurus is just a donut shape.
I suppose that if an object is not homeomorphic toward any shape at all, then it might be useful to express u as equal to infinity. That gets into some really high end shit that"s still a year ahead of me at the least, though, so I can"t really answer any more questions toward that end.
When I say high end, I mean the surfaces of neutron stars, string theory type high end. Nobody in the world completely understands that stuff yet, as the high end theoretics are the frontier of physics.
If I waited until I could come back here with a good, justified example of when it actually is beneficial to use an infinite friction coefficient, then y"all would probably be waiting about two decades minimum.
Oh, and the library here doesn"t have a scanner ><. If anyone actually wants the diagrams, PM me, and when I finally manage to find a way to scan "em in, I"ll just send ya back links.
