Physical Unit Terminology
Except as specifically and prominently noted, all numbers represented
with Arabic numerals are base 10, with the fractional portion (if any)
separated from the integral portion by a single period, which appears
nowhere else in the number.
Time on the scale of days and larger is measured on a solar calendar,
except when an absolutely precise, well-defined, and repeatable time
interval is appropriate. A day is the time it takes for the earth to
complete one rotation about its axis. A year is the time it takes for
the earth to complete one revolution around the sun, rounded to whole
days using the Gregorian method. Each year begins on the twelfth day
counting from the day on which the winter solstice falls. Each week is seven
days in length, and each day is part of exactly one week. The year is
divided into twelve months of roughly equal length, each no less than
28 days in length nor more than 31 days, as delineated in the
Gregorian method. Each day is part of exactly one month. When law
specifies a duration of one month, it signifies a period of 30 days
and some fraction of a day, ending at midnight at the end of the day
which is the 30th day following the starting day, with the starting
day considered the 1st.
Time on scales smaller than a day, and whenever a precise,
well-defined, and repeatable time interval is appropriate, is measured
in hours, minutes, seconds, and fractions of a second. A minute is
exactly 60 seconds, and an hour is exactly 60 minutes. A second is
the duration of 9192631770 periods of the radiation corresponding to
the transition between the two hyperfine levels of the ground state of
the cesium 133 atom.
The meter is the length of the path travelled by light in vacuum with
no gravitational effects during a time interval of 1/299792458 of a
second. .0254 meter is one inch, twelve inches is one foot, three
feet is one yard, and 5280 feet is one mile.
One liter is the volume of a cube each face of which is one tenth of a
meter wide. A gallon is 3.785412 liters, four quarts is a gallon, two
pints is a quart, two cups is a pint, and eight fluid ounces is a cup.
The kelvin is the fraction 1/273.16 of the thermodynamic temperature
of the triple point (point at which solid, liquid, and gaseous forms
coexist in equilibrium, under some particular pressure) of water.
To convert from Celsius to kelvin, add 273.15 to the Celsius
temperature. To convert from Fahrenheit to kelvin, add 459.67 to the
Fahrenheit temperature, then divide that sum by 1.8.
A gram is one twelfth the mass of 6.022142E+23 chemically unbound
carbon 12 atoms at rest and in their ground state (E+23 representing
multiplication by the 23rd power of ten).
A pound of mass is equal to 453.59231 grams, an ounce of mass is one
sixteenth of a pound of mass, and a ton of mass is 2000
pounds of mass.
A degree is 1/360 of a rotational sweep through a full circle.
Variants of the foregoing units with Greek or Latin scaling prefixes
have their recognized meanings. Defined as the power of ten to which
it corresponds, they are: yotta-, 24; zetta-, 21; exa-, 18; peta-, 15;
tera-, 12; giga-, 9; mega-, 6; kilo-, 3; hecto-, 2; deca-, 1; deci-,
-1; centi-, -2; milli-, -3; micro-, -6; nano-, -9; pico-, -12; femto-,
-15; atto-, -18; zepto-, -21; yocto-, -24.
One newton is the force that accelerates one kilogram at one meter per
second per second.
A pound of force is equal to 4.448222 newtons, an ounce of force is
one sixteenth of a pound of force, and a ton of force is 2000 pounds
Any other physical unit used in law or state-enforceable contract must
be defined as some precise algebraic combination of the above units,
with fully enumerated integer constants as necessary. No further
restrictions can be imposed on units used in state-enforceable
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