Years ago I tracked down a constriction ("resistance") in my house's
water system with a bucket and stopwatch to measure flow ("current") and
a fuel pump pressure gauge to measure watter pressure ("voltage") and a
schematic of the "circuit". I kind of chuckled thinking of all the
simplified explanations of electricity using water -- I found it much
easier to convert in the other direction.

As for "pounds", I was always off by the acceleration of gravity squared
in the only two one-semester courses I took which weren't metric,
Statics and Dynamics. I never could remember which of those units --
pounds mass, pounds force, poundals, slugs, aargh, had the acceleration
already built in and which didn't. I finally managed by first converting
each problem to metric, solving it, then converting the result back to
that God-awful system of units.

Roy Lewallen, W7EL

J. Mc Laughlin wrote:
My EE students, noting that the characteristic equations are the same,
regularly convert mechanical problems (of the mass-spring-damper type) into
electrical problems, solve, and then convert back to mechanical answers.
Some ME students catch on and some just do not get it. Of course, it helps
if one is using SI units all round. I continue to be in awe of MEs who
always seem to know whether the "pounds" they are talking of are
sort-of-like mass, or sort-of-like force, or money. I have even had it
suggested that energy and power are sort-of the same thing.


I am keen on Roy being the collector of titles. I have quite enough for
a lifetime. 73 Mac N8TT etc.