<p>From Dr. Math, about the question can mu be greater than 1 (you normally learn that it’s not, but sometimes it actually can be).
(Source: <a href=“Classroom Resources - National Council of Teachers of Mathematics”>Classroom Resources - National Council of Teachers of Mathematics)</p>
<p>Aluminum on Aluminum 1.3
Copper on Copper 1.3
Iron on Iron 1.0
Rubber on Steel 1.6</p>
<p>The first three can perhaps be explained in terms of something other
than “friction” (e.g., “galling,” which is the phenomenon that
requires the frame and slide of a pistol to be made from different
materials), but that’s not the case for the fourth.</p>
<p>However 1.6 has been found to be approximately a natural limit on the coefficient of friction.</p>
<p>Also, I said that the friction on the wheel was mu*N, not the airframe; I took a proportionality there as given (I ignored these things that don’t matter, as n->infinity and consider only the complexity).</p>
<p>“All of my analysis that I did in explaining this riddle was done assuming normal and reasonable frictions.”
Right. I think you understand my point of view now. Before I thought you were saying that even in the infinitely powerful treadmill case, it wouldn’t work. In my opinion, the purpose of riddles can often be to consider absurd situations. In some sense, the gedanken experiments are in this category.</p>
<p>But I’ve had enough of your nonsense… I’m done with you … you have not shown a single shred of intelligence and insight in this thread that makes you worth my time to debate this with you any longer.
I do think that you show intelligence, and I’ll even give you the benefit of the doubt that if I met you in real life you would be more classy.</p>