Alma record. (Alma, Mich.) 1878-1928, 1894-04-20
Kinetic Reaction

DEAR MODERATOR: / am glad that Mr.. G.
III. Chase of Ithaca as so much Interested H.
the subject of kinetics. Our appreciation OF
the same grand theme should make us
friends. Though we may not agree IN all
points, each one desires the truth IN the SIM
lest and most practical form.
An accident caused change IN the order
of my articles in the Moderator, and this mas
put my work at some disadvantage. A
summary" is naturally at the close of a dis
cussion, instead of appearing in the middle
After reading my Failing Bodles-ll, ana
Power of Motion-l and III" the terms
stick" and "octo. twin" and "ulta, would
no longer appear novel and strange. but de-
cidedly helpful in treating a subject which,
ut best, is somewhat abstract, and needs Just
such handles to take hold of and to nix II III
the mind.
The same reason exists for using our
special quantities as for dyne, erg, poundal.
and foot-poundal. The troublesome factor OF
acceleratlon Is eliminated Just rs enectually,
while the results are more easily obtained
and are in far better shape. Besides, the
French attenuations, dyne and erg, are alto
gether too ine to be appreciated by the plow-
boy type of manhood OF which our great
practical men are made. When we remem-
Der that to express the weight one ordinary
five-cent- piece in dynes requires four figures
for il is nearly five thousand-and that the
work of lifting the same from the floor to a
table forty inches high would require an
expenditure of half million ergs add the use
of SIX figures TO express 1T, the reader Will
appreciate the convenience of the employ
ment of such terms when applied TO the force
and work of gunpowder, horses, and men,
Savants of the laboratory will use them,
while American engineers IN practical work
will stick TO common measures and foot
pounds.
Mr.. Chase seems quite bewidered over my
use of terms, and thinks school boy could
not understand them. Let Us see. Would 1t be
difficult for boy to understand the meaning
of the word stick" or Quarter-second! IL So
hold a watch to his ear. Drop a marble, and
tell him that it will fall one foot in just that
time, and that he can always find how far a
body will fall in any number OF ticks by
squaring the number, and that the rule can
be reversed. Ii he desires to know how long
il will take a body to fall any given number
of feet, tell him 10 extract the square root OF
that number. and he has the time IN ticks.
If he inquiries about speed. tell him that a
marble in falling foot acquires a speed of
eight feet per second, which for convenience
we call an "octo." In falling it gains one octo
of speed every tick of the watch. At the end
of ten ticks the speed will be ten octos or
eighty feet per second.
Would the differential and integral calculus,
lucdly introduced by Mr.. Chase, suit the boy
better?
Our friend objects 70 my gun problem on
the ground of variable acceleration. / have a
chart that takes up that very subject, but we
did not see fit to make use of it in our first
shot. Mr.. Chase says: "Supposing the
powder TO burn instantaneously, ETC." Does
he not know that instantaneous powder would
certainly burst the gun? And then, where
would be his acceleration? Good cunning
judgment selects a grain of powder that in
burning approXimates q uniform accelera-
ton. For large guns the grains are some
times "a large as hickory nuts, measured aud
weighed, and even perforated through the
centre like a girls beads, 10 favor the proper
combustion for the ideal of uniform accelera-
ton. Besides, / am not writing volumes
like Todhunter and others on these super
critical subjects. If our friend desires to do
so he has the privilege.
That subject which "Mr. Slater seemingly
entirely ignored" about the "moments," is
certainly very important one. Will Mr..
Chase tell US exactly what he means by mo
mentsp' Il il work or force, or simply
name given TO certain abstract products
often found in formulas, and not always the
same! As understand it, force Is only apull
or push which may be measured in units of
weight, while work Is force exerted through
space OF which the foot-pound Is our COM
mon unit. Neither momentum nor Wis viva
are either of these. Then will our friend of
the calculus please tell us just what they are?
never use any such terms, and have not for
ten years.
| can tell Mr.. Chase precisely what the vim
and ulta of my Kinetic Chart mean, and
fear that he has not yet found out. The vim
is the kinetc force in pounds which is exerted
on each pound of the moving mass. | say
"kinetic force" to exclude that part of any
driving force that may be employed in over
coming friction, etc. The vim might be
called the acceerating force in pounds per
pound of mass. To save using so long a
name, especially unwieldy in chart, we
have resorted to the common expedent of
christening it, and for short say "vim." /
never once thought of its tangling up any
body Until saw Mr.. Chase's letter. Ulta has
a similar meaning, only it is applied to the
kinetic work in foot pounds that is wrought
upon a single pound of matter in producing
or destroying motion. f. A. SLATER.
Eo,ko. Na.,ool Ion 10 1904