- For units of measure primarily used in countries where English is not the main language, see the article specific to that country, a list of which can be found in the systems of measurement article.
An unusual unit of measurement is a unit of measurement that does not form part of a coherent system of measurement; especially in that its exact quantity may not be well known or that it may be an inconvenient multiple or fraction of base units in such systems. This definition is deliberately not exact since it might seem to encompass units such as the week or the light-year which are quite "usual", in the sense they are often used; if they are used out of context they may be "unusual", as demonstrated by the FFF system of units.
Unusual units of measure are sometimes used by scientists, especially physicists and mathematicians, and other technicians, engineers and computer programmers, either humorously or for real convenience when dealing with objects in the real world whose quantities in more conventional units may be awkward to use. They are also employed by journalists in an attempt to give meaningful comparisons. Whether such comparisons actually are meaningful is open to debate, since the comparative quantity itself may not be well known with much accuracy.[citation needed]
Systems of measurement
MTS units
During the twentieth century, the Soviets and French briefly used a variant of the metric system where the base unit of mass was the tonne. This meant that a kilogram was a millitonne (mt). Conversely, some companies use the megagram (Mg), to avoid confusion with long or short tons.
FFF units
| Unit | Dimension | Definition | SI Value |
|---|---|---|---|
| furlong | length | 660 ft | 201.168 m |
| firkin[1] | mass | 90 lb | 40.8233 kg |
| fortnight | time | 14 days | 1,209,600 s |
Most countries use the International System of Units (SI). In contrast, the Furlong/Firkin/Fortnight system of units of measurement draws its attention by being conservative and off-beat at the same time.[2]
One furlong per fortnight is very nearly 1 centimetre per minute (to within 1 part in 400). Indeed, if the inch were defined as 2.54 cm rather than 2.54 cm exactly, it would be 1 cm/min. Besides having the meaning of "any obscure unit", furlongs per fortnight have also served frequently in the classroom as an example on how to reduce a unit's fraction. The speed of light may be expressed as being roughly 1.8 terafurlongs per fortnight.[3][4]
SI-imperial hybrids
In the US, mongrel units are sometimes formed by a combination of traditional units, which are widely used, and metric units. Thus, "grams per fluid ounce" and "grams per pound of body weight" are common units used in sports nutrition, for example, to express the concentration of carbohydrate in a beverage.
A hybrid standard quantity used in mining is the assay ton (AT), which is as many milligrams as there are troy ounces in a ton: 29.17 grams if the ton used is the short ton, and 32.67 g if the ton used is the long ton. So to find how many ounces of gold are in a ton of rock, one measures the number of milligrams of gold in an assay ton of rock.
There are also reports of engineers using base-ten SI prefixes in combination with Imperial or US customary units, for example the kiloyard (914.4 m). The kip or kilopound is regularly used in structural engineering. Similarly, the kilofoot is quite common in US telecommunication engineering, as significant distances in cable route planning are usually given in thousands of feet. Instruments like optical time-domain reflectometers usually have an option to display results in kilofeet. Perhaps most common is the use of the thou or mil, defined as 1/1,000 of an inch (25.4 µm), frequently used to measure the thickness of very thin materials like film and plastic sheeting. A related unit is the circular mil, used for measuring the cross-sectional area of wire.
In the UK, it is still (2007) not uncommon to find the "metric foot" in use in the domestic refurbishment market. A metric foot is 30 cm and usually it is used with lumber (timber in the UK) that is only available in metric yards or 90 cm multiples (see metric inch below). Its square form is also common in some fields: for example, carpet and other flooring materials, when supplied in "tiles" (squares), are often supplied in this size.
In commercial office fitout in the UK, most suspended ceilings and raised floors are based on a 60 cm module, or 2 "metric feet".
A useful unit when working with optical pathway lengths in the lab is the one foot per nanosecond approximation for the speed of light. In electronic circuitry, where the velocity of propagation is somewhat slower than the speed of light in a vacuum, similar approximations can be used for "signal races" in the circuitry. (See light-nanosecond below.)
Derived units
There are some obscure metric units: with arbitrary units and prefixes, you can express a common unit with an unfamiliar term. Among physicists there is the in-joke replacing common units with uncommon units, as in velocity: metres per second is equivalent to hertz per dioptre (Hz/dpt). In this case, the reciprocal values of metre and second — dioptre and hertz, respectively — are used to contrive the same unit. The becquerel could also be used instead of hertz, as it is a measure of aperiodic events per time, instead of the periodic events per time measured by the hertz.
Length
Attoparsec
Parsecs are used in astronomy to measure enormous interstellar distances. A parsec is approximately 3.26 light-years or about 3.085×1016 m (1.917×1013 mi). Combining it with the "atto-" prefix yields attoparsec (apc), a conveniently human-scaled unit of about 3.085 centimetres (1.215 in) that has no obvious practical use. Interestingly, 1 attoparsec/microfortnight is nearly 1 inch/second.[5]
Light-nanosecond
The light-nanosecond was popularized as a unit of distance by Grace Hopper as the distance which a photon could travel in one billionth of a second (roughly 30 cm or one foot): "The speed of light is one foot per nanosecond." In her speaking engagements, she was well-known for passing out light-nanoseconds of wire to the audience, and contrasting it with light-microseconds (a coil of wire 1,000 times as long) and light-picoseconds (the size of ground black pepper). Over the course of her life, she had many motivations for this visual aid: including demonstrating the waste of sub-optimal programming, illustrating advances in computer speed, and simply giving young scientists and policy makers the ability to conceptualize the magnitude of very large and small numbers.[6]
Metric inch
The international inch is defined to be exactly 25.4 mm. It is approximated to 25 mm as a "metric inch".
A metric inch was used in some Soviet computers when Soviet engineers built unlicensed copies based on blueprints drawn in the US.[citation needed] Clones existed of many machines such as PDPs and early IBM PCs. The computers would look like machines made in the US, but some of the components, mainly those using longer slots or more pins, were not interchangeable due to the non-interoperable nature of the metric inch. Shorter-slotted or lower pin count original hardware was often forced in by hand if needed, as such measurement discrepancies were within tolerance; longer chips, boards, and cables, with differences that would mismatch contacts, required converters, often home-made. Because microelectronics were rare and prohibitively expensive in the Soviet Union, computers cobbled together or upgraded with mismatched original, custom-built, and cloned components, more than just common, were the norm.
The similarly derived metric foot (300 mm) was once used in the United Kingdom for some expensive materials. It was also briefly the unit used in the trade of timber when neither feet nor metres were used.[citation needed]
Storeys (stories)
All buildings are made up of storeys (stories in American English), also referred to as floors or levels. In the United States, each storey is generally 8 to 10 feet (2.4 to 3.0 m). The number of storeys is used to express the height of a building or nonbuilding structure.
In Brazil, storeys (andares in Portuguese) are used mainly by the media as a proxy for 3 metres (9.8 ft). It's normally employed in situations to express heights of buildings or elevations (news about a roller coaster, Toronto and the LHC, and article about the Cariniana, in Portuguese).
There is no global office block building code standard that specifies how tall a storey is supposed to be. In the metric world this measurement essentially means 3 metres, as most metric world drywall sheets are manufactured at this dimension.[citation needed]
Bus
In Britain, newspapers and other media will frequently refer to lengths in comparison to the length (8.4 m/27.6 ft) or height (4.4 m/14.4 ft) of a London Routemaster double-decker bus.
The UK Department of Transport (which has sole regulatory authority over this matter) has changed the definition of the maximal acceptable length of a double-decker bus length and width about 40 times since 1900, as suggested by the UK documentary "100 Years of British Buses" (1996).
Similarly, in the United States the yellow schoolbus is a common point of comparison, with an average length of around 35 feet.
Popular topics for such comparison include the blue whale, the IMAX screen, and the diplodocus.[7]
Football field (length)
The length of an American football field is 100 yd (91 m). If the end zones are included, it is 120 yd (110 m), but 100 yards is used informally as a unit, to allow easier conversion from formal measurement in feet or yards. It describes the size of a large building or a park, a distance which is not too short, but which one can walk over.
The Canadian football field is 65 yards (59 m) wide and 110 yards (100 m) long with end zones 20 yards (18 m) deep.
Media in the UK also use the football pitch as a unit of length, although an area of the Association football (soccer) pitch is not fixed, but varies within a limit of 90–120 m (98–130 yd) in length and 45–90 m (50–100 yd) in width. The usual size of a football pitch is 105 m × 68 m (115 yd × 75 yd), the area used for matches in the UEFA Champions League.
The uncertainty of the term is greater in Australia where there are four common forms of football (Rugby League, Rugby Union, Soccer, Australian Rules) and at least two other forms (eg International Rules) known to be played. One of the most common, Australian Rules Football, uses large oval shaped grounds, typically also used for cricket. The size of these varies considerably, so football field or football ground is not a very helpful measurement term.
Cricket pitch
The distance between wickets of a cricket pitch is 22 yards (20.17 metres) which is equal to 1 chain or 1/80th of a mile. It is a mid-range unit of measurement in cricketing countries.
Tall buildings
In France, the Eiffel Tower (324 m or 1,063 ft), and the UK, Nelson's Column (185 ft or 56 m), Blackpool Tower (158 m or 518 ft), Big Ben (96.3 m or 316 ft), and St Paul's Cathedral (354 ft or 108 m) are commonly used by British newspapers or reference books to give the comparative heights of buildings or, occasionally, mountains.
In Canada (and occasionally elsewhere), the Toronto CN Tower (553 m or 1,814 ft) is used as a unit of length.[8][9]
Block
A city block (in most US cities) is between 1/16 and 1/8 mi (0.1 and 0.2 km). In Manhattan, the measurement "block" usually refers to a north-south block, which is 1/20 mi (0.08 km). Within a typical large North American city, it is often only possible to travel along east-west and north-south streets, so travel distance between two points is often given in the number of blocks east-west plus the number north-south (known to mathematicians as the Manhattan Metric).
Circle of the earth
The circumference of a great circle of the earth (about 40,000 km/25,000 mi/21,600 nmi/199,000 furlongs) is often compared to large distances. For example, one might say that a large number of objects laid end-to-end at the equator "would circle the earth four and a half times".[10] According to WGS-84, the circumference of a circle through the poles (twice the length of a meridian) is 40,007,862.917 metres (131,259,392.772 ft) and the length of the equator is 40,075,016.686 m (131,479,713.537 ft). Despite the fact that the difference (0.17%) between the two is insignificant at the low precision that these quantities are typically given to, it is nevertheless often specified as being at the equator.
Earth-to-moon distance
The distance from the Earth to the moon (about 380,000 km [about 240,000 miles] on average, if measured from the Earth's surface to the moon's surface) is sometimes used in the same circumstances as the Circle of the Earth unit is used above. For example, one might say that a large number of objects laid end-to-end "would reach all the way to the moon and back two-and-a-half times."
Siriometer
The siriometer is a rarely used astronomical measure equal to one million astronomical units, i.e., one million times the average distance between the Sun and Earth. This distance is equal to about 15.8 light-years, 149.6 Pm or 4.8 parsecs, and is about twice the distance from Earth to the star Sirius.
Area
Barn
One barn is 10−28 square meters, about the cross-sectional area of a uranium nucleus. The name probably derives from early neutron-deflection experiments where the uranium nucleus was described, comparatively, as being "big as a barn."
Nanoacre
The nanoacre is a unit of real estate on a VLSI chip equal to 0.00627264 sq in (4.0468564224 mm2) or the area of a square of side length 0.0792 in (2.01168 mm). "The term gets its humor from the fact that VLSI nanoacres have costs in the same range as real acres in Silicon Valley once one figures in design and fabrication-setup costs."[11]
Square
The square is an Imperial unit of area that is used in the construction industry in North America,[12] and was historically used in Australia. One square is equal to 100 square feet. A roof's area may be calculated in square feet, then converted to square, which can then be used to order roofing materials by the square.
Fuel consumption in vehicles
The fuel consumption of vehicles is usually expressed in terms of a volume of fuel per unit of distance, or, reciprocally, of the distance traveled per unit of volume ("fuel economy"). These quantities thus resolve to an area or the reciprocal of an area.
For instance, 1 US gallon per 100 miles is about 2.35 10−8 m2, or 0.0235 mm2; 1 litre per 100 kilometers is exactly 10−8 m2 or 0.01 mm2. This can be viewed as the section of the fuel that the vehicle would consume as it advances.
Counter-intuitively, in countries using British units, this was normally expressed as "miles per gallon" (ie Imperial gallon). Latterly, this became "kilometers per litre" for which the approximate conversion is 1 km/l = 2.8 mpg.
Football field (area)
In many countries, an association football pitch, or field, is used as a man-in-the-street unit of area.[13][14] It is necessarily restricted to order of magnitude comparisons by the fact that football pitches are officially allowed to vary by a factor of 2.67 in area (between 4,050 and 10,800 m², i.e., 1.00 to 2.67 acres or roughly 0.4 to 1.1ha) although this factor drops to 2.01 in the case of pitches approved for international matches. In the UEFA Champions League a football field must be exactly 105x68m, which is an area of 7,140 m² (0.714 ha or about 1.76 acres).
An American Football field, including both end zones, is 360 ft by 160 ft (ca. 110 x 49 m), or 57,600 square-feet (5,350 m², 0.54 ha, 1.32 acres). A Canadian football field is 65 yards wide and 110 yards long (ca. 101 x 59 m) with end zones adding a combined 40 yards to the length, making it 64,350 square-feet (5,980 m², 0.60 ha, 1.477 acres)
Various countries, regions, and cities
)
The area of a familiar country, state or city is often used as a unit of measure, especially in journalism.
In the United Kingdom, Wales, equal to 20,779 km² (8,023 sq mi), is used in phrases such as "an area the size of Wales" or "twice the area of Wales".[15][16] England is 6.5 times the size of Wales, and Scotland is four times the size of Wales. The Isle of Wight (380 km² or 147 sq mi) is commonly used for smaller areas. The British comedy show The Eleven O'Clock Show parodied the use of this measurement, by introducing a news article about an earthquake in Wales, stating that an area the size of Wales was affected. The Radio 4 program More or Less introduced the idea of "kiloWales" - an area 1000 times the size of Wales.
In the United States, the areas of Rhode Island (1,545 sq mi/4,000 km2), the smallest state and therefore a relatively easy threshold to reach, Texas (268,601 sq mi/695,670 km2), commonly used due to its historic "larger than life" reputation, and less commonly used Alaska (656,425 sq mi/1,700,130 km2) are used in a similar fashion. Antarctica's Larsen B ice shelf was approximately the size of Rhode Island until it broke up in 2002. Due to Rhode Island being a relatively small unit of measurement (and, perhaps, due to its area being 33% water), many comparisons to the size of Rhode Island are somewhat imprecise.[17] The US Central Intelligence Agency uses Washington, D.C. (61.4 sq mi/159 km2) as a comparison for city-sized objects.
In Canada, the standard unit of comparison is often Prince Edward Island (5,683 km2/2,194 sq mi),[18] the smallest Canadian province.
In Russia, France (551,695 km2/213,011 sq mi) is often used as a comparison for regions of Siberia.[19] This was so popular in Soviet time that the phrase "как две Франции" (twice the size of France) became a stock phrase to denote any large area.
The country of Belgium (30,528 km2/11,787 sq mi) has also often been used when comparing areas, to the point where it has been regarded as a meme[20] and where there is a website dedicated to notable areas which have been compared to that of Belgium.
Volume
Board foot or super foot
A board foot is an American unit of volume, used for wood. It is equivalent to 1 inch × 1 foot × 1 foot (144 cu in/2,360 cm3). However, in practice, it is defined differently for hardwood and softwood. It is also found in the unit of density pounds per board foot. In Australia and New Zealand the terms super foot or superficial foot were formerly used for this unit.
Hoppus foot
A system of measure for timber in the round (standing or felled), now largely superseded by the metric system except in measuring hardwoods in certain countries. Following the so-called "quarter-girth formula" (the square of one quarter of the circumference in inches multiplied by one 144th of the length in feet), the notional log is four feet in circumference, one inch of which yields the hoppus board foot, 1 foot yields the hoppus foot, and 50 feet yields a hoppus ton. The hoppus board foot, when milled, yields a board foot. The volume yielded by the quarter-girth formula is 78.5% of cubic measure.[21]
Stère
The stère (st) is equal to a cubic metre or kilolitre. The stère is traditionally used to measure a quantity of wood. In Dutch there's also a kuub, short for kubieke meter which is almost the same. The difference is that a "kuub" is a full cubic metre, whereas a "stère", as it was used for wood, is a cubic metre of piled up woodblocks. This means that a stère is a little bit less than a kuub or full cubic metre of wood, because the spaces between the woodblocks are included in a stère while they're not in a kuub. In Finnish, the same unit is known as motti (from Swedish mått, "measure").
Olympic-size swimming pool
For larger volumes of liquid, one measure commonly used in the media in many countries is the Olympic-size swimming pool. A large Olympic swimming pool with dimensions 50 m × 25 m × 2 m (approx 164 ft × 82 ft × 6.6 ft) holds 2.5 million litres – about 2 acre-feet, 660,000 gallons, or 1/200,000 of a sydharb.
Sydney Harbour
A unit of volume used in Australia for water. One Sydney Harbour, also called a Sydharb (or sydarb), is the amount of water in Sydney Harbour: approximately 500 gigalitres (about 400,000 acre-feet).[22]
Melbourne Cricket Ground
Australia's largest and best known sports stadium, the Melbourne Cricket Ground or MCG is used there as a unit of volume.
Royal Albert Hall
The Royal Albert Hall, a large concert hall, is sometimes used as unit of volume in the UK, particularly when referring to volumes of rubbish placed in landfill.[25] The volume of the auditorium is between 3 and 3.5 million cubic feet, (between 85,000 and 99,000 cubic metres).[26]
Mass
Grave
In 1793, the French term "grave" (from "gravity") was suggested as the base unit of mass for the metric system. In 1795, however, due in no small part to the French Revolution, the name "kilogram" was adopted instead.[27]
Bag of cement
The mass of an old bag of cement was one hundredweight ~ approximately 50 kg. The amount of material that, say, an aircraft could carry into the air is often visualised as the number of bags of cement that it could lift, probably because a single bag of cement is close to the maximum that a person could safely carry.
Elephant
The weight of an elephant, sometimes more specifically "the weight of an African bull elephant" (about 6 tons), is sometimes used by palaeontologists as a unit of weight when describing the weight of large dinosaurs.[28]
Fully loaded 747
The maximum takeoff weight of most earlier models of the Boeing 747 is 800,000 pounds, or 360 tonnes. In the media, multiples of this mass can be used to describe very heavy objects, e.g. "It weighs as much as five fully-loaded 747s."
Jupiter
When reporting on the masses of extrasolar planets, astronomers often discuss them in terms of multiples of Jupiter's mass.[29] For example, "Astronomers recently discovered a planet outside our Solar System with a mass of approximately 3 Jupiters." Furthermore, the mass of Jupiter is nearly equal to one thousandth of the mass of the sun.
Sun
Solar mass (M☉ = 2.0 ×1030 kg) is also often used in astronomy when talking about masses of stars or galaxies, for example the Milky Way weighs ~6 ×1011 M☉.
Solar mass also has a special use when estimating orbital periods and distances of 2 bodies using Kepler's laws: a3 = MtotalT2, where a is length of semi-major axis in AU, T is orbital period in years and Mtotal is the combined mass of objects in M☉. In case of planet orbiting a star, Mtotal can be approximated to mean the mass of the central object. More specifically in the case of Sun and Earth the numbers reduce to Mtotal ~ 1, a ~ 1 and T ~ 1.
Energy
-
- 1 amu = 931.46 MeV/c2
Time
Shake
In nuclear engineering and astrophysics contexts, the shake (as in "two shakes of a lamb's tail", an old colloquial expression) is used as a conveniently short period of time. 1 shake is defined as 10 nanoseconds.[30]
Jiffy
In computing, the jiffy is the duration of one tick of the system timer interrupt. Typically, this time is 0.01 seconds, though in some earlier systems (such as the Commodore 8-bit machines) the jiffy was defined as 1/60 of a second, roughly equal to the vertical refresh period (i.e. the field rate) on NTSC video hardware (and the period of AC electric power in North America).
Microfortnight
One very convenient unit derived from the FFF system of units is the microfortnight, one millionth of the fundamental timeunit of FFF, which equals 1.2096 seconds. This is a fairly representative example of "hacker humor",[31] and is occasionally used in operating systems; for example, the OpenVMS TIMEPROMPTWAIT parameter is measured in microfortnights.[32]
Galactic year
The most common large-scale time scale is millions of years (Megaannum or Ma). However, for long-term measurements, this still requires rather large numbers. Using as a measure the time it takes for the solar system to revolve once around the galactic core (GY - not to be confused with Gyr for Gigayear), approximately 250 Ma, yields some easily memorizable numbers. In this scale, oceans appeared on Earth after 4 GY, life began at 5 GY, and multicellular organisms first appeared at 15 GY. Dinosaurs went extinct about 0.4 GY ago, and the true age of mammals began about 0.2 GY ago. The age of the Earth is estimated at about 20 GY.[33] Therefore a 25 year old person is 1 x 10^-7GY or 0.1µGY.
Angular Measure
Furman
The Furman is a unit of angular measure equal to 1&fras1;65,536 of a circle. It is named for Alan T. Furman, the American mathematician who adapted the CORDIC algorithm for 16-bit fixed-point arithmetic sometime around 1980.[34] 16 bits give a resolution of 216 = 65536 distinct angles.
Binary degree, binary radian, brad
A related unit of angular measure equal to 1&fras1;256 of a circle, represented by 8 bits, has found some use in machinery control where fine precision is not required, most notably crankshaft and camshaft position in internal combustion engine controllers, but there is no consensus as to its name. This unit is also used in video game programming. These units are convenient because they form cycles: for the 8-bit unit, the value overflows from 255 to 0 when a full circle has been traversed. Measures are often made using a Gray code, which is trivially converted into more conventional notation.
Angular mil
The angular mil is used by many military organisations to measure plane angle and so to triangulate distances, given an object's apparent and actual size. It is approximately the angle which has a tangent of 1/1000; in NATO standard, this is rounded to 1&fras1;6400 of a circle, although other definitions are in use. Its name derives from Latin: millesimus ("thousandth") and so the fact it is used mostly by the military is coincidental to its name.[35]
Energy
Tons of TNT
The explosive power of various amounts of the explosive TNT (kiloton, megaton, gigaton) is often used as a unit of explosion power, and sometimes of asteroid impacts and violent explosive volcanic eruptions. One ton of TNT is 4.184 × 109 joules, or 109 thermochemical calories (≈3.964 × 106 BTU). This definition is not based on the actual physical properties of TNT.
Hiroshima bomb
The energy released by the Hiroshima bomb explosion (about 15 kT TNT equivalent, or 6 x 1013 J) is often used by geologists as a unit when describing the energy of asteroid impacts and violent explosive volcanic eruptions.
Foe
A foe is a unit of energy equal to 1044 joules (≈9.478 × 1040 BTU) that was coined by physicist Gerry Brown of Stony Brook University. To measure the staggeringly immense amount of energy produced by a supernova, specialists occasionally use the "foe", an acronym derived from the phrase [ten to the power of] fifty-one ergs, or 1051 ergs. This unit of measure is convenient because a supernova typically releases about one foe of observable energy in a very short period of time (which can be measured in seconds).
Other metric-compatible scales
Langley: energy intensity
The langley (symbol Ly) is used to measure solar radiation or insolation. It is equal to one thermochemical calorie per square centimetre (4.184×104 J/m² or ≈3.684 BTU/sq ft) and was named after Samuel Pierpont Langley.
Stokes: kinematic viscosity
One of the few CGS units to see wider use, one stokes (symbol S or St) is a unit of kinematic viscosity, defined as 1 cm²/s, i.e., 10−4 m²/s (≈1.08×10−3 sq ft/s).
Jansky: electromagnetic flux
In radio astronomy, the unit of electromagnetic flux is the jansky (symbol Jy), equivalent to 10−26 watts per square metre per hertz (= 10−26 kg/s2 in base units, about 8.8×10−31 BTU/ft2). It is named after the pioneering radio astronomer Karl Jansky. The brightest natural radio sources have flux densities of the order of one to one hundred jansky.
Metre of water equivalence
A material-dependent unit used in nuclear and particle physics and engineering to measure the thickness of shielding, for example around a nuclear reactor, particle accelerator, or radiation or particle detector. 1 mwe of a material is the thickness of that material that provides the equivalent shielding of one metre (≈39.4 in) of water.
This unit is commonly used in underground science to express the extent to which the overburden (usually rock) shields an underground space or laboratory from cosmic rays. The actual thickness of overburden through which cosmic rays must traverse to reach the underground space varies as a function of direction due to the shape of the overburden, which may be a mountain, or a flat plain, or something more complex like a cliff side. To express the depth of an underground space in mwe (or kmwe for deep sites) as a single number, the convention is to use the depth beneath a flat overburden at sea level that gives the same overall cosmic ray muon flux in the underground location.
Dietary intake
Dietary intake of energy, or of various nutrients, is usually expressed as a quantity per day, rather than per second. Sometimes body mass is factored in.
An intake of 2500 kilocalories per day is about 121 watts. This gives the average power of the body, dissipated over 24 hours in heat and mechanical energy.
An intake of 0.5 gram of protein per day and per kilogram of body weight is about 5.79 10−9 s−1, the reciprocal of 172,800,000 seconds or 2000 days. This means it would take you 2000 days to eat your weight of protein.
Units For Unconventional Measurements
Encyclopedias, Bibles, and the Library of Congress: data storage capacities
When the Compact Disc began to be used as a data storage device, the CD-ROM, journalists had to compare the disc capacity (650 MB) to something everyone could imagine. Since many Western households have at least one Christian Bible, and the Bible is a comparatively long book, it was often chosen for this purpose. The King James Version of the Bible in uncompressed plain 8-bit text contains about 4.5 million characters,[36] so a CD-ROM can store about 150 Bibles.
The Encyclopædia Britannica is another common data size metric — it contains approximately 300 million characters, so two copies would fit comfortably onto a CD-ROM.[citation needed]
The term Library of Congress is sometimes used as a unit of measurement when discussing large amounts of data. It refers to the US Library of Congress. One Library of Congress is used as approximately 20 tebibytes of uncompressed textual data,[37][38] or 10 terabytes according to other uses.[39][40]
In most cases, diagrams and photographs are not included in the total — since these take considerably more space than text, this would be an important consideration for practical storage of large book collections. In practice, diagrams can often be expressed more compactly using vector graphics, and data compression software can pack more text into the available space. It is possible to compress English text to about 11% of its original size.[41] Thus one might claim that the entire Library of Congress could be packed onto a single 2.2 terabyte storage unit — excluding the pictures.
A similar unit of measure for early computers was phone numbers and phone books.
Gillette: laser power
A unit described by Theodore Harold Maiman as an early measure of laser output power. The measure was simply the number of razor blades through which the laser could burn a hole. This measurement was especially convenient as the first lasers were pulsed ruby lasers, making it otherwise difficult to measure the output power. Also, due to the relative uniformity of razor blades manufactured by The Gillette Company, it had some usefulness as a rough comparison.[citation needed]
Thus, scientists would brag about having a "4 Gillette" laser versus their competitor's puny "2 Gillette" laser. (Maiman claims that the first laser was a "2 Gillette" laser.[citation needed])
Sagan: scalar
A whimsical unit of measure equalling at least 4,000,000,000. Based on the quote "billions of stars" used by Carl Sagan and popularized with the derivation "billions and billions of stars" by Johnny Carson.
Big Mac Index: purchasing power parity
A similar system used in the UK is the 'Mars bar'. Tables of prices in Mars Bars have intermittently appeared in newspapers over the last 20 years, usually to illustrate changes in wages or prices over time without the confusion caused by inflation.[45]
Garn
The Garn is NASA's unit of measure for symptoms resulting from space adaptation syndrome, the response of the human body to weightlessness in space, named after US Senator Jake Garn, who became exceptionally spacesick during an orbital flight in 1985. If an astronaut is completely incapacitated by space adaptation syndrome, he or she is under the effect of one Garn of symptoms.[46]
KLOC: computer program length
A computer programming expression, the K-LOC or KLOC, pronounced kay-lok, standing for "kilo-Lines of Code", i.e., thousand lines of code. The unit is used, especially by IBM managers,[47] to express the amount of work required to develop a piece of software. Given that estimates of 20 lines of functional code per day per programmer were often used, it is apparent that 1 K-LOC could take one programmer as long as 50 working days, or 10 working weeks.
Error rates in programming are also measured in "Errors per K-LOC", which is called the defect density. NASA's SATC is one of the few organisations to claim zero defects in a large (>500K-LOC) project, for the space shuttle software.
Nibble
A measure of quantity of data or information, the "nibble" (sometimes spelled "nybble" or "nybl") is equal to 4 bits, or one half of the common 8-bit byte. The nibble is used to describe the amount of memory used to store a digit of a number stored in binary-coded decimal format, or to represent a single hexadecimal digit.
FLOPS
It is also used to compare the performance of algorithms in practice.[citation needed]
Nines
Numbers very close to, but below one are often expressed in nines (N - not to be confused with the unit newton), that is in the number of nines following the decimal separator in writing the number in question. For example, "three nines" or "3N" indicates 0.999 or 99.9%, "four nines five" or "4N5" is the expression for the number 0.99995 or 99.995%.[citation needed]
Typical areas of usage are:
Proof: alcohol concentration
Up to the 20th century, alcoholic spirits were assessed in the UK by mixing with gunpowder and testing the mixture to see if it would still burn; spirit that just passed the test was said to be at 100° proof. The UK now uses percentage alcohol by volume at 20 °C (68 °F), where spirit at 100° proof is approximately 57.15% ABV; the US uses a proof number of twice the ABV at 60 °F (15.5 °C).[citation needed]
Savart: audible frequency ratio
An 18th century unit for measuring the frequency ratio of two sounds, it is equal to 1/300 of an octave, or 1/25 of a semitone. Still used in some programs, but considered too rough for most purposes. Cent is preferred.
Scoville heat unit: pepper hotness
The Scoville scale is a measure of the hotness of a chili pepper. It is the degree of dilution in sugar water of a specific chili pepper extract when a panel of 5 tasters can no longer detect its 'heat'.[48] Pure capsaicin (the chemical responsible for the 'heat') has 1.6×107 Scoville heat units.[49]
ASTA pungency unit: pepper hotness
ASTA (American Spice Trade Association) pungency unit is based on a scientific method of measuring chili pepper 'heat'. The technique utilizes high performance liquid chromatography to identify and measure the concentrations of the various compounds that produce a heat sensation. Scoville units are roughly 15 times higher than Pungency units while measuring capsaicin, so a rough conversion is to multiply Pungency by 15 to obtain Scoville heat units.[50]
Strontium unit: radiation dose
The strontium unit, formerly known as the Sunshine Unit (symbol S.U.), is a unit of biological contamination by radioactive substances (specifically strontium-90). It is equal to one picocurie of Sr-90 per gram of body calcium. Since about 2% of the human body mass is calcium, and Sr-90 has a half-life of 28.78 years, releasing 6.697+2.282 MeV per disintegration, this works out to about 1.065×10−12 grays per second. The permissible body burden was established at 1,000 S.U.
Dol: pain
The dol (from the Latin word for pain, dolor) is a unit of measurement for pain.
James D. Hardy, Herbert G. Wolff, and Helen Goodell of Cornell University proposed the unit based on their studies of pain during the 1940s-1950s. They defined one dol to equal to "just noticeable differences" (jnd's) in pain. The unit never came into widespread use and other methods are now used to assess the level of pain experienced by patients.
Schmidt sting pain index and Starr sting pain index
These are pain scales rating the relative pain caused by different Hymenopteran stings. Schmidt has refined his Schmidt Sting Pain Index (scaled from 1 to 4) with extensive anecdotal experience, culminating in a paper published in 1990 which classifies the stings of 78 species and 41 genera of Hymenoptera. The Starr sting pain scale uses the same 1-to-4 scaling. In practice, the Comparative Pain Scale is used by doctors when working with patients.[51]
Erlang: telecommunications traffic volume
The erlang, named after A. K. Erlang, as a dimensionless unit is used in telephony as a statistical measure of the offered intensity of telecommunications traffic on a group of resources. Traffic of one erlang refers to a single resource being in continuous use, or two channels being at fifty percent use, and so on, pro rata. A lot of telecommunications management and forecasting software uses this unit on a day to day basis—but strictly speaking it is a telecom sector specific network stress measurement unit.
Amazon River: large volumes of water flow
The volume of discharge of the Amazon River sometimes used to describe large volumes of water flow such as ocean currents. The unit is equivalent to 216,000 m3/s. [52]
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