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NOTES ON MATHEMATICS.
v = 8.02 xJ 9 X 0.25
* 0.025 X 1440
Solving the problem step by step we have
:
v = 8.02 xJ 2.25
* 36
v = 8.02 X \A).0625
7/ = 8.02 X 0.25.
v = 2.005 feet per second.
In mechanical formulas, if not otherwise specified, it
is always safe to assume the letter g to mean acceleration
due to gravity, usually taken as 32.2 feet or 9.82 meters. In
formulas relating to heat the letter / usually signifies the
mechanical equivalent of heat = 778 foot pounds of energy
;
but in formulas relating to strength of materials the letter J
usually signifies the polar moment of inertia, and the letter /
the least rectangular moment of inertia. The letter x always
expresses the unknown quantity. The following Greek letters
are also used more or less. The letter ~, called pi, is used to
signify the ratio of the circumference to the diameter of a
circle, and is usually taken as 3.1416. % called sigma, usually
signifies the sum of a number of quantities. The letter A,
called delta, usually signifies small increments of matter.
The letter 6, called theta, or the lefter <£, called phi, usually
signifies some particular angle, sometimes also the coefficient
of friction. But all these letters may be employed to express
anything, although it is usually safe, if not otherwise specified.
to expect their meaning to be as stated. It is always customary
to express known quantities by the first letters in the alphabet,
such as a, &, c, etc., and unknown quantities by such letters as
x, y, z, etc.
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