For intro students (and others), it is important to
note that quantities that are "dimensionless" for the
purposes of mathematical convenience still do have
very real dimensions for the purpose of conceptual
understanding. Take coeff of friction - this is
"dimensionless" when a problem is to be worked, but it
truly has units of frictional force/normal force. The
fact that the N's cancel doesn't change the conceptual
point that the quantities divided to produce our mu
are quite different, even though they have the same
unit of measure. The same could be said for radians: a
meter of arc length is physically very different from
a meter of radial length. One's curved, the other
isn't. John Barrere Apex HS Apex, NC
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