[net.nlang] RATE: a dictionary view

jlg@lanl-a.UUCP (06/03/83)

FLAME!!!!!!
I' getting tired of people who use some general dictionary for the
definition of a methematical or technical term.  Especially when they
ridicule others (who have more sense) who use the proper mathematical
definition.  "Rate" implies change!!!!  For example: speed (a rate)
is calculated as the CHANGE in position divided by the CHANGE in time.
Without "CHANGE" the calculation of speed would be impossible.  Even
for a stationary object, time still CHANGES -- thats how you calculate
a speed of zero.  If time did not change the calculation would require
dividing zero by zero -- an undefined quantity!!
Flame off

Except when talking to a hick town cop, the word "rate" without any
modifiers is usually taken to mean "the rate of change with time."  For
example: if a boat were sinking one might refer to its "sink rate",
meaning the rate at which it sinks with respect to time.  (Aircraft
pilots refer to "sink rate" all the time when discussing landing and
take-off maneuvers.)  Notice that "sink" incorporates the notion of
change within its definition.  "Rate of speed" is a difficult thing
to analyze.  As pointed out above "speed" is a rate, not a process like
"sink" or "move".  "Speed" clearly implies "change", that is "change in
position" and "change in time".  But what change is being measured by
"rate of speed"?  If "rate of speed" means "rate of change in position,"
(with respect to time by default) then the phrase means "speed" and is
merely redundant.  "Rate of speed" can't mean "rate of change of time"
(with respect to time) -- this is always one.  The only other meaning
which prevents redundancy is "rate of change of speed", this is accel-
eration.

In fact, the only people that use "rate of speed" are the hick town
cops.  Everyone else will use "speed" or "acceleration" which ever is
appropriate.

Note also that "rate" doesn't have to be with respect to time.  One can
refer to "the rate of fuel consumption with respect to speed" for example.
But if "time" is not used the you must state explicitly what is.

Sorry for the length of this note, but one of the things that rankle me
is someone who refers to authority in order to talk through his hat.

levy@princeto.UUCP (06/07/83)

Once and for all: if by "rate of speed" you mean "speed", you're being
redundant.  If you mean "acceleration", you're being unclear (at best).
So why use the expression at all?
                              Silvio Levy