about canonical physical, temporal, linguistic, and mathematical representations that reduce reasoning and conversion complexity. part of representational reasoning.
fahrenheit (celsius °c), rankine (kelvin × 1.8)
fluid ounce (30 ml), cup (250 ml), pint (500 ml), quart (1 l), gallon (us) (4 l), gallon (uk) (5 l), barrel (100 l)
ounce (28 g), pound (0.5 kg), stone (6 kg), ton (1 mg), slug (14.5939 kg)
inch (2.5 cm), foot (30 cm), yard (1 m), mile (1.6 km), nautical mile (2 km), astronomical unit (150 gm), light year (9 pm), parsec (31 pm), ångström (1×10⁻¹⁰ m)
minute (60 s), hour (100 s), foot per second (0.3048 m/s)
kilocalorie (0.0042 mj), calorie (4.184 j), erg (1×10⁻⁷ j), foot-pound (1.4 j), foot-pound-force (1.3558 j), btu (1 kj)
dyne (1×10⁻⁵ n), pound-force (4.448 n)
octet (8 bits), megabyte (8×10⁶ bits), terabyte (8×10¹² bits), mebibit (1,048,576 bits), kibibyte (8192 bits)
psi (7 kpa), atm (100 kpa), mmhg (133 pa), inch of mercury (3.386 kpa), torr (133.322 pa), psig (6.895 kpa gauge), bar (100 kpa), atmosphere technical (98.0665 kpa)
horsepower (750 w), btu per hour (0.293 w)
acre (4000 m²), hectare (10,000 m²)
km/h (0.278 km/ks), mph (0.45 km/ks), knot (0.5 km/ks)
minute (60 s), hour (3.6 ks), day (86.4 ks), week (604.8 ks), month (~2.592 megaseconds), year (~31.5 megaseconds)
fahrenheit delta (kelvin), gallon per mile (l/100 km), ppi (points per inch)
planck units are defined using only the speed of light, the gravitational constant, the reduced planck constant, and the boltzmann constant.
use negative years instead of specifying bce. if someone writes 1996, we assume it means the common era. if someone writes year -1996, we assume it is before an era, and by analogy to positive years, it should be understood as part of the same timeline.
negative_year = 1 - bce_year because bce counts from 1, astronomical counts from 0.1757674897 = 1 gs, 757 Ms, 674 ks, 8 hs, 97 s.prefixes = %w[p n mi m c d da h k me g t pe e z y ro qu]
units = %w[m g s a k mol cd hz n pa j w c v f ohm wb t h lm lx bq gy sv kat rad sr]
combinations = prefixes.product(units).map { |pre, unit| pre + unit }
puts combinations.join ", "see also simplified mathematical notation