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Re: When Physical Intuition Fails



Bob Sciamanda wrote:

I need to re-cast that last post. It should read:

It must be noted that the frictional force (f=mu*N) which effects the
linear acceleration should not be assumed to be the same as the frictional
force (F=MU*N) which effects dissipation. It is by VIOLATING this dictum
that one reaches Mike's conclusion (which I would re-word as: the energy
dissipated cannot quantitatively be accounted for as the line integral of
a CONSTANT frictional force).

Thanks for the clarification.

I'm a little mystified by the notion of MU*N as "the"
force which affects dissipation. The usual model of
dissipation involves ultra-high-speed fluctuations in
the force. So the actual force cannot be described by
MU*N... even though its time-average can be described
by mu*N. The time-average suffices for accounting for
the momentum tranfer, but the detailed, unaveraged
force is required to explain the dissipation.

Or have I completely missed the point?

It seems to me that this skidding-wheel problem bears
many similarities to the rail-car coupling problem and
to the ballistic-pendulum problem ... and can be (and
should be) attacked in the same way.
http://lists.nau.edu/cgi-bin/wa?A2=ind9911&L=phys-l&P=R37089

This posting is the position of the writer, not that of Gregory Peccary
or Olivia de Javelina.

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.