"Andy Coggan" wrote in message k.net...

Conveying precise concepts requires precise use of terminology. While I
agree with you that simple "pedal speed" might be sufficient should it be
used within context, it might not be if, for example, the plot was presented
out of context. Hence, "circumferential pedal velocity", i.e, the speed and
direction that the pedal travels.

It looks like my previous critique was not quite accurate.
In order to make a graph of pedal velocity versus some other quantity,
you would actually need to make a four dimensional plot. This is
because pedal
velocity, as opposed to pedal
speed, is not roughly constant for a given value of the other
quantity, so you
must include time to make a plot. That is, you need to make a graph
with respect
to the scalars: speed, direction, time, quantity you used in your
graph.

To highlight the complication you introduce by insisting on using
pedal velocity, note that the graph of the speed of a pedal rotating
in a circle
at constant speed consists of a single point, while the graph of its
velocity
is a 3-dimensional figure, a helix (this is what I was thinking of
previously).

Once again, I use an opportunity to differentiate myself from most
scientists
by admitting when I have made a mistake.

-ilan