James McLean wrote
If two different masses were sliding down an inclined
plane with the same frictional force, the heavier onewould
win. (Note that this is *not* the same as with the same
friction *coefficient*.)
The point James makes is interesting but isn't it quite an
artificial situation. I can't think of a real situation
where the frictional forces would be equal.
In his reply to Martha Takats, John Mallinckrodt referred to
take paper he and Harvey Leff wrote in AJP in 92. This is a
paper that all of us who teach introductory mechanics should
have to hand and read again each time we re-embark on our
class work.