Generated callable unit vars — see commensura.units.gen. Use via :as u.
Generated callable unit vars — see commensura.units.gen. Use via :as u.
ratio of the sound pressure of 1 dyn/cm^2 to a source of strength 1 cm^3/s
ratio of the sound pressure of 1 dyn/cm^2 to a source of strength 1 cm^3/s
NIST Handbook 44 has a typographical error (forgetting to underline feet in one place on middle of page C-16 in 2003 edition) with respect to this, but it's clear from corroborating different figures in that document and NIST Special Publication 811, Sec. B.6, that the survey foot is the proper definition. Have filed errata with NIST and requested confirmation. 2003-08-27 Received confirmation (years later) that all of my reported errors were indeed errors and would be fixed. Note that it was apparently not fixed until the 2007 edition. 2010 edition of NIST Handbook 44 is apparently correct. (see section C-2.) http://ts.nist.gov/WeightsAndMeasures/pubs.cfm
NIST Handbook 44 has a typographical error (forgetting to underline feet in one place on middle of page C-16 in 2003 edition) with respect to this, but it's clear from corroborating different figures in that document and NIST Special Publication 811, Sec. B.6, that the survey foot is the proper definition. Have filed errata with NIST and requested confirmation. 2003-08-27 Received confirmation (years later) that all of my reported errors were indeed errors and would be fixed. Note that it was apparently not fixed until the 2007 edition. 2010 edition of NIST Handbook 44 is apparently correct. (see section C-2.) http://ts.nist.gov/WeightsAndMeasures/pubs.cfm
1/16 of the weighted average mass of the 3 naturally occurring neutral isotopes of oxygen
1/16 of the weighted average mass of the 3 naturally occurring neutral isotopes of oxygen
1/16 of the mass of a neutral oxygen 16 atom
1/16 of the mass of a neutral oxygen 16 atom
Convenient for describing molecular sizes
Convenient for describing molecular sizes
The time between successive perihelion passages of the earth.
The time between successive perihelion passages of the earth.
The arpent is 100 square perches, but the perche seems to vary a lot and can be 18 feet, 20 feet, or 22 feet. This measure was described as being in common use in Canada in 1934 (Websters 2nd). The value given here is the Paris standard arpent.
The arpent is 100 square perches, but the perche seems to vary a lot and can be 18 feet, 20 feet, or 22 feet. This measure was described as being in common use in Canada in 1934 (Websters 2nd). The value given here is the Paris standard arpent.
Standard atmospheric pressure (exact) See https://physics.nist.gov/cgi-bin/cuu/Value?stdatm
Standard atmospheric pressure (exact) See https://physics.nist.gov/cgi-bin/cuu/Value?stdatm
atomic mass unit error is +/- 52 in last 2 digits (defined to be 1/12 of the mass of carbon 12)
atomic mass unit error is +/- 52 in last 2 digits (defined to be 1/12 of the mass of carbon 12)
astronomical unit, approximately the average radius of earth's orbit around the sun.
astronomical unit, approximately the average radius of earth's orbit around the sun.
The "point" is used to measure rainfall in Australia
The "point" is used to measure rainfall in Australia
Number of items in a mole Defined exactly by the SI rules that go into effect May 20, 2019 https://physics.nist.gov/cgi-bin/cuu/Value?na
Number of items in a mole Defined exactly by the SI rules that go into effect May 20, 2019 https://physics.nist.gov/cgi-bin/cuu/Value?na
Given in Realm of Measure as the difference between successive shoe sizes
Given in Realm of Measure as the difference between successive shoe sizes
Used to measure cross section for particle physics collision, said to have originated in the phrase "big as a barn".
Used to measure cross section for particle physics collision, said to have originated in the phrase "big as a barn".
Bell would be sounded every 30 minutes.
Bell would be sounded every 30 minutes.
H. Berthold tried to create a metric version of the didot point in 1878.
H. Berthold tried to create a metric version of the didot point in 1878.
For whole blood. For blood components, a blood unit is the quanity of the component found in a blood unit of whole blood. The human body contains about 12 blood units of whole blood.
For whole blood. For blood components, a blood unit is the quanity of the component found in a blood unit of whole blood. The human body contains about 12 blood units of whole blood.
Bohr radius This can also be calculated as alpha / (4 pi Rinfinity) 2022 CODATA value, 5.29177210544e-11 m There is some discrepancy between calculating this in terms of other constants and the CODATA value. uncertainty is +/- 82 in last 2 digits. https://physics.nist.gov/cgi-bin/cuu/Value?bohrrada0
Bohr radius This can also be calculated as alpha / (4 pi Rinfinity) 2022 CODATA value, 5.29177210544e-11 m There is some discrepancy between calculating this in terms of other constants and the CODATA value. uncertainty is +/- 82 in last 2 digits. https://physics.nist.gov/cgi-bin/cuu/Value?bohrrada0
Boltzmann's constant. Defined exactly by the SI rules that go into effect May 20, 2019
Boltzmann's constant. Defined exactly by the SI rules that go into effect May 20, 2019
Sometimes the term "baud" is incorrectly used to refer to bits per second. Baud refers to symbols per second. Modern modems transmit several bits per symbol.
Sometimes the term "baud" is incorrectly used to refer to bits per second. Baud refers to symbols per second. Modern modems transmit several bits per symbol.
Binary radian--used to fit angular measurements into a byte. Questionable but what the hell.
Binary radian--used to fit angular measurements into a byte. Questionable but what the hell.
measure and then sweeping the top.
measure and then sweeping the top.
and then sweep the top. Sifted means
and then sweep the top. Sifted means
sifting the flour directly into a
sifting the flour directly into a
Volume of 8 inch high cylinder with 18.5
Volume of 8 inch high cylinder with 18.5
The line was used in 19th century USA to measure width of buttons.
The line was used in 19th century USA to measure width of buttons.
Not all machines had 8 bit bytes, but these days most of them do. But beware: for transmission over modems, a few extra bits are used so there are actually 10 bits per byte.
Not all machines had 8 bit bytes, but these days most of them do. But beware: for transmission over modems, a few extra bits are used so there are actually 10 bits per byte.
speed of light in vacuum (exact) The speed of light is the same to all observers in all local frames. The relation between the meter and the second is thus fixed by this definition. This is good.
speed of light in vacuum (exact) The speed of light is the same to all observers in all local frames. The relation between the meter and the second is thus fixed by this definition. This is good.
dip and sweep" refers to dipping a
dip and sweep" refers to dipping a
The density of flour depends on the
The density of flour depends on the
measuring method. "Scooped", or
measuring method. "Scooped", or
Energy to go from 14.5 to 15.5 degC
Energy to go from 14.5 to 15.5 degC
International Table calorie, 4.1868 J
International Table calorie, 4.1868 J
1/100 energy to go from 0 to 100 degC
1/100 energy to go from 0 to 100 degC
kcal/mol is used as a unit of energy by physical chemists.
kcal/mol is used as a unit of energy by physical chemists.
Energy to go from 19.5 to 20.5 degC
Energy to go from 19.5 to 20.5 degC
defined in 1824 to be the volume of
defined in 1824 to be the volume of
unit of luminous intensity. The official 2019 SI definition: The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540e12 Hz, K_cd, to be 683 when expressed in the unit lm W^−1, which is equal to cd sr W^−1 , or cd sr kg^−1 m^−2 s^3, where the kilogram, metre and second are defined in terms of h, c and Δν_Cs.
unit of luminous intensity. The official 2019 SI definition: The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540e12 Hz, K_cd, to be 683 when expressed in the unit lm W^−1, which is equal to cd sr W^−1 , or cd sr kg^−1 m^−2 s^3, where the kilogram, metre and second are defined in terms of h, c and Δν_Cs.
Standard unit for luminous intensity
Standard unit for luminous intensity
water which weighed 10 pounds at 62 deg F with a pressure of 30 inHg. In 1963 it was defined to be the space occupied by 10 pounds of distilled water of density 0.998859 g/ml weighed in air of density 0.001217 g/ml against weights of density 8.136 g/ml. The value given here is given by [1] as an exact value.
water which weighed 10 pounds at 62 deg F with a pressure of 30 inHg. In 1963 it was defined to be the space occupied by 10 pounds of distilled water of density 0.998859 g/ml weighed in air of density 0.001217 g/ml against weights of density 8.136 g/ml. The value given here is given by [1] as an exact value.
Used for angular deviation of light through a prism.
Used for angular deviation of light through a prism.
The cesium frequency which defines the second: The unperturbed ground-state hyperfine transition frequency of the caesium 133 atom
The cesium frequency which defines the second: The unperturbed ground-state hyperfine transition frequency of the caesium 133 atom
http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20150713
emitted by the amount of radon that is in equilibrium with 1 gram of radium.
emitted by the amount of radon that is in equilibrium with 1 gram of radium.
area of a one-inch diameter circle
area of a one-inch diameter circle
2022 CODATA value https://physics.nist.gov/cgi-bin/cuu/Value?re uncertainty is +/- 13 in the last 2 digits
2022 CODATA value https://physics.nist.gov/cgi-bin/cuu/Value?re uncertainty is +/- 13 in the last 2 digits
Supposed to be the insulance required to keep a resting person comfortable indoors. The value given is from NIST and the CRC, but [5] gives a slightly different value of 0.875 ft^2 degF hr / Btu. Misc other measures
Supposed to be the insulance required to keep a resting person comfortable indoors. The value given is from NIST and the CRC, but [5] gives a slightly different value of 0.875 ft^2 degF hr / Btu. Misc other measures
These are for nonalkalized cocoa
These are for nonalkalized cocoa
to an even 1/72 inch by computer
to an even 1/72 inch by computer
listed as "k_e" or sometimes "k The repulsive electric force between two charged pointlike particles is: coulombconst q1 q2 / dist^2
listed as "k_e" or sometimes "k The repulsive electric force between two charged pointlike particles is: coulombconst q1 q2 / dist^2
The crith is the mass of one liter of hydrogen at standard temperature and pressure.
The crith is the mass of one liter of hydrogen at standard temperature and pressure.
used informally in UK physics labs
used informally in UK physics labs
Defined in 1910 as the radioactivity
Defined in 1910 as the radioactivity
C-value U.S. insulation conductance rating
C-value U.S. insulation conductance rating
Meant to be electromotive force of a Daniell cell, but in error by .04 V
Meant to be electromotive force of a Daniell cell, but in error by .04 V
Measures permeability to fluid flow. One darcy is the permeability of a medium that allows a flow of cc/s of a liquid of centipoise viscosity under a pressure gradient of atm/cm.
Measures permeability to fluid flow. One darcy is the permeability of a medium that allows a flow of cc/s of a liquid of centipoise viscosity under a pressure gradient of atm/cm.
Defined by U.S. Department of Defense as a unit used in radar measurements.
Defined by U.S. Department of Defense as a unit used in radar measurements.
The standard North American deal [OED]
The standard North American deal [OED]
The size of a degree in the Celsius scale. This is identical to the size of a Kelvin. WARNING: This should only be used when you're indicating the difference between two temperatures, (say, how much energy to raise the temperature of a gram of water by 5 degrees Celsius, not for absolute temperatures. (I wonder if they should go entirely to eliminate this confusion...) For calculating absolute temperatures, use the Celsius[] or C[] functions below.
The *size* of a degree in the Celsius scale. This is identical to the size of a Kelvin. WARNING: This should only be used when you're indicating the *difference* between two temperatures, (say, how much energy to raise the temperature of a gram of water by 5 degrees Celsius, *not* for absolute temperatures. (I wonder if they should go entirely to eliminate this confusion...) For calculating absolute temperatures, use the Celsius[] or C[] functions below.
WARNING: These should only be used when you're indicating the difference between two temperatures, (say, how much energy to raise the temperature of a gram of water by 5 degrees Fahrenheit, not for absolute temperatures. (I wonder if they should go entirely to eliminate this confusion...) For calculating absolute temperatures, use the Fahrenheit[] or F[] functions below.
WARNING: These should only be used when you're indicating the *difference* between two temperatures, (say, how much energy to raise the temperature of a gram of water by 5 degrees Fahrenheit, *not* for absolute temperatures. (I wonder if they should go entirely to eliminate this confusion...) For calculating absolute temperatures, use the Fahrenheit[] or F[] functions below.
The size of a degree in the Fahrenheit scale.
The *size* of a degree in the Fahrenheit scale.
The Reaumur scale was used in Europe and particularly in France. It is defined to be 0 at the freezing point of water and 80 at the boiling point. Reaumur apparently selected 80 because it is divisible by many numbers.
The Reaumur scale was used in Europe and particularly in France. It is defined to be 0 at the freezing point of water and 80 at the boiling point. Reaumur apparently selected 80 because it is divisible by many numbers.
The size of a degree in the Fahrenheit scale.
The *size* of a degree in the Fahrenheit scale.
This seems to be the dominant value
This seems to be the dominant value
measures reciprocal of lens focal length
measures reciprocal of lens focal length
Approximate volume of a longton weight of sea water used to measure ship displacement
Approximate volume of a longton weight of sea water used to measure ship displacement
The US dollar is chosen arbitrarily to be the primitive unit of money. The dollar must be defined for use in the CPISource (providing historical purchasing power of the dollar) and for CurrencySource (providing exchange rate information (and things like the price of Gold)) so you can change the fundamental unit of currency, but you have to be able to turn it into a dollar if you want to use these other sources. If you want to define your own base currency, and you want currency conversions to still work, you should (for now) define the base currency as its 3-letter ISO-4217 currency code (say, "EUR" or "JPY"). This will allow the currency converter to unambiguously figure out which currency you mean. The units "Euro", "euro", the Euro symbol €, the Japanese Yen symbol ¥, the U.K. pound symbol ţ, and "dollar" are special cases that also work.
The US dollar is chosen arbitrarily to be the primitive unit of money. The dollar must be defined for use in the CPISource (providing historical purchasing power of the dollar) and for CurrencySource (providing exchange rate information (and things like the price of Gold)) so you can change the fundamental unit of currency, but you have to be able to turn it into a dollar if you want to use these other sources. If you want to define your own base currency, and you want currency conversions to still work, you should (for now) define the base currency as its 3-letter ISO-4217 currency code (say, "EUR" or "JPY"). This will allow the currency converter to unambiguously figure out which currency you mean. The units "Euro", "euro", the Euro symbol €, the Japanese Yen symbol ¥, the U.K. pound symbol ţ, and "dollar" are special cases that also work.
Length of the diagonal of a square with
Length of the diagonal of a square with
This is the time required to travel from the ascending node to the next ascending node.
This is the time required to travel from the ascending node to the next ascending node.
The drop was an old "unit" that was replaced by the minim. But I was told by a pharmacist that in his profession, the conversion of 20 drops per ml is actually used.
The drop was an old "unit" that was replaced by the minim. But I was told by a pharmacist that in his profession, the conversion of 20 drops per ml is actually used.
These are for Dutch processed cocoa
These are for Dutch processed cocoa
Frankish coin called the "denier minted in the late 700's. There were 240 deniers to the pound.
Frankish coin called the "denier minted in the late 700's. There were 240 deniers to the pound.
Base of natural logarithm 'e' was previously used to be the charge of the electron, but changed to this. Mathematicians and particle physicists may battle this out.
Base of natural logarithm 'e' was previously used to be the charge of the electron, but changed to this. Mathematicians and particle physicists may battle this out.
Synonym used at https://physics.nist.gov/cgi-bin/cuu/Value?hr
Synonym used at https://physics.nist.gov/cgi-bin/cuu/Value?hr
when it is accelerated through 1 V
when it is accelerated through 1 V
Defined exactly by the SI rules that take effect on May 20, 2019 https://physics.nist.gov/cgi-bin/cuu/Value?e also called "e but that's reserved for the base of the natural logarithm.
Defined exactly by the SI rules that take effect on May 20, 2019 https://physics.nist.gov/cgi-bin/cuu/Value?e also called "e but that's reserved for the base of the natural logarithm.
supposed to be measure from elbow to fingertips
supposed to be measure from elbow to fingertips
Originally intended to be 4 grain but this value ended up being used in the London diamond market
Originally intended to be 4 grain but this value ended up being used in the London diamond market
Change in gravitational acceleration over horizontal distance
Change in gravitational acceleration over horizontal distance
permittivity of vacuum This is the 2022 CODATA value. Uncertainty is +/- 14 in the last 2 digits. https://physics.nist.gov/cgi-bin/cuu/Value?ep0
permittivity of vacuum This is the 2022 CODATA value. Uncertainty is +/- 14 in the last 2 digits. https://physics.nist.gov/cgi-bin/cuu/Value?ep0
EU standard spirits measure See http://bundesrecht.juris.de/eo_1988/anhang_c_119.html
EU standard spirits measure See http://bundesrecht.juris.de/eo_1988/anhang_c_119.html
Energy acquired by a particle with charge e
Energy acquired by a particle with charge e
Charge that must flow to deposit or
Charge that must flow to deposit or
element. (The chemical and physical values are off slightly from what is obtained by multiplying by amu_chem or amu_phys. These values are from a 1991 NIST publication.) Note that there is a Faraday constant which is equal to N_A e and hence has units of C/mol.
element. (The chemical and physical values are off slightly from what is obtained by multiplying by amu_chem or amu_phys. These values are from a 1991 NIST publication.) Note that there is a Faraday constant which is equal to N_A e and hence has units of C/mol.
liberate one gram equivalent of any
liberate one gram equivalent of any
Originally defined as the distance from fingertip to fingertip with arms fully extended.
Originally defined as the distance from fingertip to fingertip with arms fully extended.
Convenient for describing nuclear sizes Nuclear radius is from 1 to 10 fermis
Convenient for describing nuclear sizes Nuclear radius is from 1 to 10 fermis
Density of down at standard pressure. The best down has 750-800 fillpower.
Density of down at standard pressure. The best down has 750-800 fillpower.
The finger is defined as either the width
The finger is defined as either the width
Measures intensity of ultraviolet light with wavelength 296.7 nm.
Measures intensity of ultraviolet light with wavelength 296.7 nm.
Construction term referring to sidewalk.
Construction term referring to sidewalk.
means to lightly spoon into a measure
means to lightly spoon into a measure
measure into a bin, and then sweeping
measure into a bin, and then sweeping
the excess off the top. "Spooned
the excess off the top. "Spooned
Used in radio astronomy to measure the energy incident on the receiving body across a specified frequency bandwidth. [12]
Used in radio astronomy to measure the energy incident on the receiving body across a specified frequency bandwidth. [12]
Illuminance from a 1 candela source at a distance of one foot
Illuminance from a 1 candela source at a distance of one foot
First definition of the printers point made by Pierre Fournier who defined it in 1737 as 1/12 of a cicero which was 0.1648 inches.
First definition of the printers point made by Pierre Fournier who defined it in 1737 as 1/12 of a cicero which was 0.1648 inches.
Both register ton and shipping ton derive from the "tun cask" of wine.
Both register ton and shipping ton derive from the "tun cask" of wine.
pied de roi, the standard of Paris.
pied de roi, the standard of Paris.
a law passed on 10 Dec 1799 which
a law passed on 10 Dec 1799 which
Used in refrigeration engineering.
Used in refrigeration engineering.
Newtonian gravity constant From 2022 CODATA figures. There is a standard uncertainty in the last two figures of +/- 15. Unchanged since 2018. Given by https://physics.nist.gov/cgi-bin/cuu/Value?bg The gravitational force between the centers of two (spherelike) bodies is: G mass1 mass2 / dist^2
Newtonian gravity constant From 2022 CODATA figures. There is a standard uncertainty in the last two figures of +/- 15. Unchanged since 2018. Given by https://physics.nist.gov/cgi-bin/cuu/Value?bg The gravitational force between the centers of two (spherelike) bodies is: G mass1 mass2 / dist^2
for earth's gravitational field (note that "gal" is for gallon but "Gal" is the standard symbol for the gal which is evidently a shortened form of "galileo".)
for earth's gravitational field (note that "gal" is for gallon but "Gal" is the standard symbol for the gal which is evidently a shortened form of "galileo".)
molar gas constant, Now exactly defined in terms of Avogadro's constant and Boltzmann's constant. https://physics.nist.gov/cgi-bin/cuu/Value?r
molar gas constant, Now exactly defined in terms of Avogadro's constant and Boltzmann's constant. https://physics.nist.gov/cgi-bin/cuu/Value?r
So you can convert energy to gallons gasoline. This now matches the EPA definition for MPGe. This definition was changed in the Frink data from 1.4e8 J/gallon (which is about 38.88 kWh/gallon) on 2022-11-03. The previous definition may have been more accurate for very efficient combustion of gasoline, but this makes it match with EPA definitions.
So you can convert energy to gallons gasoline. This now matches the EPA definition for MPGe. This definition was changed in the Frink data from 1.4e8 J/gallon (which is about 38.88 kWh/gallon) on 2022-11-03. The previous definition may have been more accurate for very efficient combustion of gasoline, but this makes it match with EPA definitions.
The orbital period of a body in circular orbit at a distance of 1 au from the sun. Calculated from Kepler's third law.
The orbital period of a body in circular orbit at a distance of 1 au from the sun. Calculated from Kepler's third law.
distance between points where the same foot hits the ground
distance between points where the same foot hits the ground
Exact definition appears in DIN 16507, a German standards document of 1954. Adopted more broadly in 1966 by ???
Exact definition appears in DIN 16507, a German standards document of 1954. Adopted more broadly in 1966 by ???
Mass which is accelerated at 1 cm/s^2 by 1 gram force
Mass which is accelerated at 1 cm/s^2 by 1 gram force
The grain is the same in all three weight systems. It was originally defined as the weight of a barley corn taken from the middle of the ear.
The grain is the same in all three weight systems. It was originally defined as the weight of a barley corn taken from the middle of the ear.
std acceleration of gravity (exact) see https://physics.nist.gov/cgi-bin/cuu/Value?gn
std acceleration of gravity (exact) see https://physics.nist.gov/cgi-bin/cuu/Value?gn
said to be 3/5 of a 20.75 in cubit.
said to be 3/5 of a 20.75 in cubit.
Egyptian Royal cubit in [11]. It is
Egyptian Royal cubit in [11]. It is
This approximate value is obtained
This approximate value is obtained
Planck's constant, exactly defined by the SI rules that take effect on May 20, 2019. https://physics.nist.gov/cgi-bin/cuu/Value?h
Planck's constant, exactly defined by the SI rules that take effect on May 20, 2019. https://physics.nist.gov/cgi-bin/cuu/Value?h
log[10]/log[2] bits, or the entropy of a uniformly-distributed random variable over 10 symbols.
log[10]/log[2] bits, or the entropy of a uniformly-distributed random variable over 10 symbols.
Standard of linear measure used in Persian dominions of the Arabic empire 7-8th cent. Is equal to two French feet.
Standard of linear measure used in Persian dominions of the Arabic empire 7-8th cent. Is equal to two French feet.
Alternate spelling, used in many translations
Alternate spelling, used in many translations
Area of land granted by the 1862 Homestead Act of the United States Congress
Area of land granted by the 1862 Homestead Act of the United States Congress
Used to sell firewood for residences, often confusingly called a "cord
Used to sell firewood for residences, often confusingly called a "cord
WMAP data, +/- 0.9 km/s/megaparsec From Sky & Telescope, July 2015 p.30
WMAP data, +/- 0.9 km/s/megaparsec From Sky & Telescope, July 2015 p.30
Also gram-force s^2/m according to [15]
Also gram-force s^2/m according to [15]
This point was created by a group directed by Fermin Didot in 1881 and is associated with the imprimerie nationale. It doesn't seem to have been used much.
This point was created by a group directed by Fermin Didot in 1881 and is associated with the imprimerie nationale. It doesn't seem to have been used much.
second deposits .001118 gram of silver from an aqueous solution of silver nitrate.
second deposits .001118 gram of silver from an aqueous solution of silver nitrate.
Defined as the current which in one
Defined as the current which in one
Defined as the resistance of a uniform column of mercury containing 14.4521 gram in a column 1.063 m long and maintained at 0 degC.
Defined as the resistance of a uniform column of mercury containing 14.4521 gram in a column 1.063 m long and maintained at 0 degC.
began counting on July 16, AD 622 when Muhammad emigrated to Medina (the year of the Hegira). They need 11 leap days in 30 years to stay in sync with the lunar year which is a bit longer than the 29.5 days of the average month.
began counting on July 16, AD 622 when Muhammad emigrated to Medina (the year of the Hegira). They need 11 leap days in 30 years to stay in sync with the lunar year which is a bit longer than the 29.5 days of the average month.
They have 29 day and 30 day months.
They have 29 day and 30 day months.
Suggested by Richard Terrett You can of course write kJ_mol.
Suggested by Richard Terrett You can of course write kJ_mol.
K. G. Jansky identified radio waves coming
K. G. Jansky identified radio waves coming
(http://www.jargon.org) as being the duration of a clock tick for measuring wall-clock time. Supposedly the value used to be 1/60 sec or 1/50 sec depending on the frequency of AC power, but then 1/100 sec became more common. On linux systems, this term is used and for the Intel based chips, it does have the value of .01 sec. The Jargon File also lists two other definitions: millisecond, and the time taken for light to travel one foot.
(http://www.jargon.org) as being the duration of a clock tick for measuring wall-clock time. Supposedly the value used to be 1/60 sec or 1/50 sec depending on the frequency of AC power, but then 1/100 sec became more common. On linux systems, this term is used and for the Intel based chips, it does have the value of .01 sec. The Jargon File also lists two other definitions: millisecond, and the time taken for light to travel one foot.
The kelvin is the unit of temperature.
The kelvin is the unit of temperature.
Josephson Constant Direct measurement of the volt is difficult. Until recently, laboratories kept Weston cadmium cells as a reference, but they could drift. In 1987 the CGPM officially recommended the use of the Josephson effect as a laboratory representation of the volt. The Josephson effect occurs when two superconductors are separated by a thin insulating layer. A "supercurrent" flows across the insulator with a frequency that depends on the potential applied across the superconductors. This frequency can be very accurately measured. The Josephson constant K_J, which is equal to 2 elementarycharge/h, relates the measured frequency to the potential. From 1990 to 2019, the value of the Josephson constant was specified as as exactly 4.835979ee+14 Hz/V . The new 2019 SI redefinition caused it to be changed to a slightly different (but exact rational number value) See: https://physics.nist.gov/cgi-bin/cuu/Value?kjos
Josephson Constant Direct measurement of the volt is difficult. Until recently, laboratories kept Weston cadmium cells as a reference, but they could drift. In 1987 the CGPM officially recommended the use of the Josephson effect as a laboratory representation of the volt. The Josephson effect occurs when two superconductors are separated by a thin insulating layer. A "supercurrent" flows across the insulator with a frequency that depends on the potential applied across the superconductors. This frequency can be very accurately measured. The Josephson constant K_J, which is equal to 2 elementarycharge/h, relates the measured frequency to the potential. From 1990 to 2019, the value of the Josephson constant was specified as as exactly 4.835979ee+14 Hz/V . The new 2019 SI redefinition caused it to be changed to a slightly different (but exact rational number value) See: https://physics.nist.gov/cgi-bin/cuu/Value?kjos
The kelvin was redefined in 2019 as: The kelvin, symbol K, is the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380649e−23 when expressed in the unit J K^−1, which is equal to kg m^2 s^−2 K^−1, where the kilogram, metre and second are defined in terms of h, c and Δν_Cs." (The defined frequency of the cesium-133 atom.)
The kelvin was redefined in 2019 as: The kelvin, symbol K, is the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380649e−23 when expressed in the unit J K^−1, which is equal to kg m^2 s^−2 K^−1, where the kilogram, metre and second are defined in terms of h, c and Δν_Cs." (The defined frequency of the cesium-133 atom.)
The standard unit of mass. The 2019 SI definition of the kilogram is: The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.62607015e−34 when expressed in the unit J s, which is equal to kg m^2 s^−1, where the metre and the second are defined in terms of c and Δν_Cs. (The defined frequency of the cesium-133 atom.)
The standard unit of mass. The 2019 SI definition of the kilogram is: The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.62607015e−34 when expressed in the unit J s, which is equal to kg m^2 s^−1, where the metre and the second are defined in terms of c and Δν_Cs. (The defined frequency of the cesium-133 atom.)
Diamond Crystal salt, from package Note that Morton kosher salt is much denser.
Diamond Crystal salt, from package Note that Morton kosher salt is much denser.
k-value, insulation conductance/in thick
k-value, insulation conductance/in thick
This unit and its symbol l were adopted by the CIPM in 1879. The alternative symbol for the liter, L, was adopted by the CGPM in 1979 in order to avoid the risk of confusion between the letter l and the number 1. Thus, although both l and L are internationally accepted symbols for the liter, to avoid this risk the preferred symbol for use in the United States is L.
This unit and its symbol l were adopted by the CIPM in 1879. The alternative symbol for the liter, L, was adopted by the CGPM in 1979 in order to avoid the risk of confusion between the letter l and the number 1. Thus, although both l and L are internationally accepted symbols for the liter, to avoid this risk the preferred symbol for use in the United States is L.
the temperature of its maximum density under a pressure of 1 atm. This was supposed to be 1000 cubic cm, but it was discovered that the original measurement was off. In 1964, the liter was redefined to be exactly 1000 cubic centimeters.
the temperature of its maximum density under a pressure of 1 atm. This was supposed to be 1000 cubic cm, but it was discovered that the original measurement was off. In 1964, the liter was redefined to be exactly 1000 cubic centimeters.
Chinese unit of length 100 li is considered a day's march
Chinese unit of length 100 li is considered a day's march
The Roman pound varied significantly
The Roman pound varied significantly
from 4210 grains to 5232 grains. Most of
from 4210 grains to 5232 grains. Most of
The 365.25 day year is specified in NIST publication 811
The 365.25 day year is specified in NIST publication 811
Also defined as '.1 in' or as '1e-8 Wb'
Also defined as '.1 in' or as '1e-8 Wb'
The liter was defined in 1901 as the
The liter was defined in 1901 as the
Used to measure the extent that the frequency of light is shifted by a magnetic field.
Used to measure the extent that the frequency of light is shifted by a magnetic field.
Molecules per cubic meter of an ideal gas at STP. Loschmidt did work similar to Avogadro.
Molecules per cubic meter of an ideal gas at STP. Loschmidt did work similar to Avogadro.
moves around the sun, the moon has to revolve a bit farther to get into the full moon configuration.
moves around the sun, the moon has to revolve a bit farther to get into the full moon configuration.
The Lustrum was a Roman purification ceremony that took place every five years. Classically educated Englishmen used this term.
The Lustrum was a Roman purification ceremony that took place every five years. Classically educated Englishmen used this term.
The 2019 SI definition of the meter is:
The 2019 SI definition of the meter is:
Standardized in 1979, but given as 2 qt in some references
Standardized in 1979, but given as 2 qt in some references
luminous energy per area, used to measure photographic exposure
luminous energy per area, used to measure photographic exposure
The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299_792_458 when expressed in the unit m s^−1, where the second is defined in terms of the caesium frequency Δν_Cs.
The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299_792_458 when expressed in the unit m s^−1, where the second is defined in terms of the caesium frequency Δν_Cs.
Illuminance from a 1 candela source at a distance of one meter
Illuminance from a 1 candela source at a distance of one meter
Inverse of ohm, hence ohm spelled backward
Inverse of ohm, hence ohm spelled backward
Official NIST definition. Another choice is 1ee-3 radian.
Official NIST definition. Another choice is 1ee-3 radian.
reciprocal color temperature. The name abbreviates micro reciprocal degree.
reciprocal color temperature. The name abbreviates micro reciprocal degree.
Volume occupied by one mole of an ideal gas at STP. Units m^3/mol
Volume occupied by one mole of an ideal gas at STP. Units m^3/mol
An "amount of substance". The 2019 SI definition is: The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6.02214076e23 elementary entities. This number is the fixed numerical value of the Avogadro constant, N_A, when expressed in the unit mol^−1 and is called the Avogadro number. The amount of substance, symbol n, of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, any other particle or specified group of particles.
An "amount of substance". The 2019 SI definition is: The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6.02214076e23 elementary entities. This number is the fixed numerical value of the Avogadro constant, N_A, when expressed in the unit mol^−1 and is called the Avogadro number. The amount of substance, symbol n, of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, any other particle or specified group of particles.
This is obviously an average for the limiting case... so is accurate in the long term but useless for adding an offset to a specific date.
This is obviously an average for the limiting case... so is accurate in the long term but useless for adding an offset to a specific date.
EPA definition, of miles per gallon, electric. See above.
EPA definition, of miles per gallon, electric. See above.
permeability of vacuum 2022 CODATA. Uncertainty is +/- 20 in the last 2 digits.
permeability of vacuum 2022 CODATA. Uncertainty is +/- 20 in the last 2 digits.
Originally the width of the thumbnail, or 1/16 ft. This took on the general meaning of 1/16 and settled on the nail of a yard or 1/16 yards as its final value. [12]
Originally the width of the thumbnail, or 1/16 ft. This took on the general meaning of 1/16 and settled on the nail of a yard or 1/16 yards as its final value. [12]
Supposed to be one minute of latitude at the equator. That value is about 1855 m. Early estimates of the earth's circumference were a bit off. The value of 1852 m was made the international standard in 1929. The US did not accept this value until July 1, 1954. The UK switched in 1970. The value of this unit was adopted by the First International Extraordinary Hydrographic Conference, Monaco, 1929, under the name "International nautical mile.
Supposed to be one minute of latitude at the equator. That value is about 1855 m. Early estimates of the earth's circumference were a bit off. The value of 1852 m was made the international standard in 1929. The US did not accept this value until July 1, 1954. The UK switched in 1970. The value of this unit was adopted by the First International Extraordinary Hydrographic Conference, Monaco, 1929, under the name "International nautical mile.
hay and "old" hay rather than a new unit
hay and "old" hay rather than a new unit
New and old here seem to refer to "new
New and old here seem to refer to "new
Luminance: the intensity per projected
Luminance: the intensity per projected
Half of a byte. Sometimes equal to different lengths such as 3 bits.
Half of a byte. Sometimes equal to different lengths such as 3 bits.
All Earth's oceans ETOPO1 data, https://www.ngdc.noaa.gov/mgg/global/etopo1_ocean_volumes.html
All Earth's oceans ETOPO1 data, https://www.ngdc.noaa.gov/mgg/global/etopo1_ocean_volumes.html
François Ambroise Didot, one of a family of printers, changed Fournier's definition around 1770 to fit to the French units then in use.
François Ambroise Didot, one of a family of printers, changed Fournier's definition around 1770 to fit to the French units then in use.
space occupied by 1 kg of pure water at
space occupied by 1 kg of pure water at
Used in U.S. before July 1, 1954
Used in U.S. before July 1, 1954
These olympic measures were not as
These olympic measures were not as
common as the other greek measures.
common as the other greek measures.
force which accelerates an ounce at 1 ft/s^2
force which accelerates an ounce at 1 ft/s^2
distance between points where alternate feet touch the ground
distance between points where alternate feet touch the ground
The palm is a unit defined as either the width
The palm is a unit defined as either the width
Persian unit of length usually thought to be between 3 and 3.5 miles
Persian unit of length usually thought to be between 3 and 3.5 miles
from the sun to a point having heliocentric parallax of 1 arcsec (derived from parallax second). IAU Resolution B2, 2015 (link below) cites two textbooks as saying that "the parsec is defined as exactly (648000 / pi) au which is equivalent to the previous definition included here: au radian / arcsec but it does not quote any standards body. (648000 is 3600 * 180, the number of arcseconds in a semicircle. This is thus not a correct trigonometric scale, but a small-angle approximation. The rigorous trigonometric measure would be given by d = r/tan[theta] or specifically au / tan[arcsec]) Note that the parsec is defined not as the angle when the Earth is on opposite sides of the Sun, but half that angle.
from the sun to a point having heliocentric parallax of 1 arcsec (derived from parallax second). IAU Resolution B2, 2015 (link below) cites two textbooks as saying that "the parsec is defined as exactly (648000 / pi) au which is equivalent to the previous definition included here: au radian / arcsec but it does not quote any standards body. (648000 is 3600 * 180, the number of arcseconds in a semicircle. This is thus not a correct trigonometric scale, but a small-angle approximation. The rigorous trigonometric measure would be given by d = r/tan[theta] or specifically au / tan[arcsec]) Note that the parsec is defined not as the angle when the Earth is on opposite sides of the Sun, but half that angle.
Roman Land Surveyors", Dilke gives 295.7 mm.
Roman Land Surveyors", Dilke gives 295.7 mm.
Abbreviated "d" in reference to a
Abbreviated "d" in reference to a
This value appears in numerous sources. In "The
This value appears in numerous sources. In "The
or 33.35 cm, used in Gaul & Germany in 1st c BC
or 33.35 cm, used in Gaul & Germany in 1st c BC
An explosive compound, Pentaerythrite tetranitrate used in plastic explosive like Semtex
An explosive compound, Pentaerythrite tetranitrate used in plastic explosive like Semtex
Originated in Pennsylvania oil fields, from the winetierce
Originated in Pennsylvania oil fields, from the winetierce
A//17 pin is 17/16 in long in the USA.
A//17 pin is 17/16 in long in the USA.
action of one joule over one second
action of one joule over one second
+/- 0.8 km http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20150713
fixed the meter at 3 frenchfeet + 11.296 lignes.
fixed the meter at 3 frenchfeet + 11.296 lignes.
Designed to be lightweight, thin,
Designed to be lightweight, thin,
Alcohol content measured by volume at 60 degrees Fahrenheit. This is a USA measure. In Europe proof=percent.
Alcohol content measured by volume at 60 degrees Fahrenheit. This is a USA measure. In Europe proof=percent.
Used in Japanese phototypesetting Q is for quarter
Used in Japanese phototypesetting Q is for quarter
can be expressed as 1/lambda = R (1/m^2 - 1/n^2). where R is a number that various slightly from element to element. For hydrogen, R_H is the value, and for heavy elements, the value approaches Rinfinity.
can be expressed as 1/lambda = R (1/m^2 - 1/n^2). where R is a number that various slightly from element to element. For hydrogen, R_H is the value, and for heavy elements, the value approaches Rinfinity.
The angle subtended at the center of a circle by an arc equal in length to the radius of the circle. A circle thus subtends an angle of 2 pi radians.
The angle subtended at the center of a circle by an arc equal in length to the radius of the circle. A circle thus subtends an angle of 2 pi radians.
Used for internal capacity of ships
Used for internal capacity of ships
keV X-rays. Different types of radiation are weighted by the Relative Biological Effectiveness (RBE).
keV X-rays. Different types of radiation are weighted by the Relative Biological Effectiveness (RBE).
side length of 1 royal egyptian cubit. This is divided into 40 digits which are not the same size as the digits based on the royal cubit.
side length of 1 royal egyptian cubit. This is divided into 40 digits which are not the same size as the digits based on the royal cubit.
Roentgen Equivalent Physical, the amount of radiation which , absorbed in the body, would liberate the same amount of energy as 1 roentgen of X rays would, or 97 ergs.
Roentgen Equivalent Physical, the amount of radiation which , absorbed in the body, would liberate the same amount of energy as 1 roentgen of X rays would, or 97 ergs.
Ionizing radiation that produces 1 statcoulomb of charge in 1 cc of dry air at stp.
Ionizing radiation that produces 1 statcoulomb of charge in 1 cc of dry air at stp.
Old pound based on bronze coinage, the earliest money of Rome BC 338 to BC 268.
Old pound based on bronze coinage, the earliest money of Rome BC 338 to BC 268.
same names as the subdivisions of the pound,
same names as the subdivisions of the pound,
from which all the other units are derived.
from which all the other units are derived.
There is some uncertainty in this definition
There is some uncertainty in this definition
The subdivisions of the Roman foot have the
The subdivisions of the Roman foot have the
Roman double pace (basic military unit)
Roman double pace (basic military unit)
but we can't have the names for different
but we can't have the names for different
the standards were obtained from the weight
the standards were obtained from the weight
Sometimes it appears spelled this way
Sometimes it appears spelled this way
The 2019 SI definition of the second is:
The 2019 SI definition of the second is:
Measure of sound absorption equal to the absorbing power of one square foot of a perfectly absorbing material. The sound absorptivity of an object is the area times a dimensionless absorptivity coefficient.
Measure of sound absorption equal to the absorbing power of one square foot of a perfectly absorbing material. The sound absorptivity of an object is the area times a dimensionless absorptivity coefficient.
(nit is from latin nitere = to shine.)
(nit is from latin nitere = to shine.)
Ice cream scoops are labeled with a number specifying how many scoops fill a quart.
Ice cream scoops are labeled with a number specifying how many scoops fill a quart.
Also used for peas, beans, rye, salt
Also used for peas, beans, rye, salt
The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency Δν_Cs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9_192_631_770 when expressed in the unit Hz, which is equal to s^−1.
The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency Δν_Cs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9_192_631_770 when expressed in the unit Hz, which is equal to s^−1.
there is uncertainty. Six large Roman measures survive with volumes ranging from 34.4 in^3 to 39.55 in^3. Three of them cluster around the size given here.
there is uncertainty. Six large Roman measures survive with volumes ranging from 34.4 in^3 to 39.55 in^3. Three of them cluster around the size given here.
Basic unit of Roman volume. As always,
Basic unit of Roman volume. As always,
Defined to be a smaller companion to the barn, but it's too small to be of much use.
Defined to be a smaller companion to the barn, but it's too small to be of much use.
Used for ship's cargo freight or timber
Used for ship's cargo freight or timber
Used to measure non-sole shoe leather
Used to measure non-sole shoe leather
Time required for the moon to orbit the earth
Time required for the moon to orbit the earth
or the time required for the earth to make one rotation relative to the stars. The more usual solar day is the time required to make a rotation relative to the sun. Because the earth moves in its orbit, it has to turn a bit extra to face the sun again, hence the solar day is slightly longer.
or the time required for the earth to make one rotation relative to the stars. The more usual solar day is the time required to make a rotation relative to the sun. Because the earth moves in its orbit, it has to turn a bit extra to face the sun again, hence the solar day is slightly longer.
The time for the earth to make one revolution around the sun relative to the stars.
The time for the earth to make one revolution around the sun relative to the stars.
of X-rays. It is defined to be 1/3029.45 of the spacing of calcite planes at 18 degC. It was intended to be exactly 1e-13 m, but was later found to be off slightly.
of X-rays. It is defined to be 1/3029.45 of the spacing of calcite planes at 18 degC. It was intended to be exactly 1e-13 m, but was later found to be off slightly.
Resistance of a meter long column of mercury with a 1 mm cross section.
Resistance of a meter long column of mercury with a 1 mm cross section.
Dose equivalent: dosage that has the
Dose equivalent: dosage that has the
Unit of gamma ray dose delivered in one hour at a distance of 1 cm from a point source of 1 mg of radium enclosed in platinum .5 mm thick.
Unit of gamma ray dose delivered in one hour at a distance of 1 cm from a point source of 1 mg of radium enclosed in platinum .5 mm thick.
at temperature T is given by sigma T^4. Exactly defined as of 2019 but since pi is transcendental, it doesn't have a finite representation. https://physics.nist.gov/cgi-bin/cuu/Value?sigma
at temperature T is given by sigma T^4. Exactly defined as of 2019 but since pi is transcendental, it doesn't have a finite representation. https://physics.nist.gov/cgi-bin/cuu/Value?sigma
Angular extent of one sign of the zodiac
Angular extent of one sign of the zodiac
The weights were derived from these two
The weights were derived from these two
80 turns of thread on a reel with a 54 in circumference (varies for other kinds of thread)
80 turns of thread on a reel with a 54 in circumference (varies for other kinds of thread)
measurements relating to dark adapted eyes.
measurements relating to dark adapted eyes.
pound-force system. Used in space applications where in/sec^2 was a natural acceleration measure.
pound-force system. Used in space applications where in/sec^2 was a natural acceleration measure.
Height of Oliver R. Smoot Jr. see: http://aether.lbl.gov/www/personnel/smoot/smoot-measure.html
Height of Oliver R. Smoot Jr. see: http://aether.lbl.gov/www/personnel/smoot/smoot-measure.html
The time for the earth to rotate on its axis relative to the sun.
The time for the earth to rotate on its axis relative to the sun.
supposed to be distance from thumb to pinky with full hand extension
supposed to be distance from thumb to pinky with full hand extension
Rarely used for astronomical measurements
Rarely used for astronomical measurements
And half again as thick is a split deal.
And half again as thick is a split deal.
Solid angle which cuts off an area of the surface of
Solid angle which cuts off an area of the surface of
This is the St Petersburg or Pittsburg standard. Apparently the term is short for "standard hundred which was meant to refer to 100 pieces of wood (deals). However, this particular standard is equal to 120 deals which are 12 ft by 11 in by 1.5 inches (not the standard deal).
This is the St Petersburg or Pittsburg standard. Apparently the term is short for "standard hundred which was meant to refer to 100 pieces of wood (deals). However, this particular standard is equal to 120 deals which are 12 ft by 11 in by 1.5 inches (not the standard deal).
Standard width between railroad track
Standard width between railroad track
standard temperature, exactly defined
standard temperature, exactly defined
The radiant emittance by a blackbody
The radiant emittance by a blackbody
the sphere equal to that of a square with sides of length equal to the radius of the sphere. A sphere thus subtends 4 pi steradians. Also a dimensionless unit (length^2/length^2) If you have radians as a fundamental unit, and want to have steradians tracked correctly, replace the first definition with sr := radian^2
the sphere equal to that of a square with sides of length equal to the radius of the sphere. A sphere thus subtends 4 pi steradians. Also a dimensionless unit (length^2/length^2) If you have radians as a fundamental unit, and want to have steradians tracked correctly, replace the first definition with sr := radian^2
area of an extended luminous source.
area of an extended luminous source.
16th century unit, sometimes defined as .5, 2, or 4 bushels depending on the location. It probably doesn't make a lot of sense to define in terms of imperial bushels. Zupko gives a value of 2 Winchester grain bushels or about 70.5 liters.
16th century unit, sometimes defined as .5, 2, or 4 bushels depending on the location. It probably doesn't make a lot of sense to define in terms of imperial bushels. Zupko gives a value of 2 Winchester grain bushels or about 70.5 liters.
earth-sun distance at perihelion
earth-sun distance at perihelion
Plus/minus 65 km, http://www.ifa.hawaii.edu/info/press-releases/solar_radius/
Plus/minus 65 km, http://www.ifa.hawaii.edu/info/press-releases/solar_radius/
Used for measuring the sedimentation coefficient for centrifuging.
Used for measuring the sedimentation coefficient for centrifuging.
The TeX typesetting system uses
The TeX typesetting system uses
New name for thaitical, not to be confused with the Thai currency called "Thailand_baht".
New name for thaitical, not to be confused with the Thai currency called "Thailand_baht".
Heat required to raise the temperature of a tonne of water from 14.5 to 15.5 degC.
Heat required to raise the temperature of a tonne of water from 14.5 to 15.5 degC.
2022 CODATA value https://physics.nist.gov/cgi-bin/cuu/Value?sigmae The "classical" cross-section of an electron when illuminated by radiation. Uncertainty is +/- 62 in the last 2 digits.
2022 CODATA value https://physics.nist.gov/cgi-bin/cuu/Value?sigmae The "classical" cross-section of an electron when illuminated by radiation. Uncertainty is +/- 62 in the last 2 digits.
Used for measuring solid blocks of wood
Used for measuring solid blocks of wood
So you can write tons TNT, this is a defined, not measured, value
So you can write tons TNT, this is a defined, not measured, value
One ton refrigeration is the rate of heat extraction required turn one ton of water to ice in a day. Ice is defined to have a latent heat of 144 Btu/lb.
One ton refrigeration is the rate of heat extraction required turn one ton of water to ice in a day. Ice is defined to have a latent heat of 144 Btu/lb.
Torricelli, should not be confused. Acording to [15] the torr is actually atm/760 which is slightly different.
Torricelli, should not be confused. Acording to [15] the torr is actually atm/760 which is slightly different.
Exactly defined. Differs from mmHg by about 1 part in 7 million.
Exactly defined. Differs from mmHg by about 1 part in 7 million.
Accepted symbol is Torr These units, both named after Evangelista
Accepted symbol is Torr These units, both named after Evangelista
units with two identically named systems used for silver and used for trade purposes
units with two identically named systems used for silver and used for trade purposes
The mean interval between vernal equinoxes. Differs from the sidereal year by 1 part in 26000 due to precession of the earth about its rotational axis combined with precession of the perihelion of the earth's orbit.
The mean interval between vernal equinoxes. Differs from the sidereal year by 1 part in 26000 due to precession of the earth about its rotational axis combined with precession of the perihelion of the earth's orbit.
The SI defines "ua" as the international symbol for the astronomical unit, but the IAU recommends that "au" be used. See 2012 resolution B2 here: http://www.iau.org/static/resolutions/IAU2012_English.pdf
The SI defines "ua" as the international symbol for the astronomical unit, but the IAU recommends that "au" be used. See 2012 resolution B2 here: http://www.iau.org/static/resolutions/IAU2012_English.pdf
Concession to electrical engineers without adding the questionable "u as a general prefix.
Concession to electrical engineers without adding the questionable "u as a general prefix.
of particular coins. The one given here is
of particular coins. The one given here is
based on the Gold Aureus of Augustus which
based on the Gold Aureus of Augustus which
Error is 38 million years Source: ibid
Error is 38 million years Source: ibid
United States official doubletime pace
United States official doubletime pace
United States official military pace
United States official military pace
luminous intensity of 1 cm^2 of platinum at its temperature of solidification (2045 K)
luminous intensity of 1 cm^2 of platinum at its temperature of solidification (2045 K)
time a sentry stands watch or a ship's crew is on duty.
time a sentry stands watch or a ship's crew is on duty.
If it's half as thick as the standard deal it's called a "whole deal"!
If it's half as thick as the standard deal it's called a "whole deal"!
Wien's Displacement Law gives the frequency at which the the Planck spectrum has maximum intensity. The relation is lambda T = b where lambda is wavelength, T is temperature and b is the Wien displacement. This relation is used to determine the temperature of stars. This is the 2022 CODATA value. NIST claims this is exact, but they give an equation with a random unexplained, inexact, divisor, b = (h c / k) / 4.965114231... https://physics.nist.gov/cgi-bin/cuu/Value?bwien
Wien's Displacement Law gives the frequency at which the the Planck spectrum has maximum intensity. The relation is lambda T = b where lambda is wavelength, T is temperature and b is the Wien displacement. This relation is used to determine the temperature of stars. This is the 2022 CODATA value. NIST claims this is exact, but they give an equation with a random unexplained, inexact, divisor, b = (h c / k) / 4.965114231... https://physics.nist.gov/cgi-bin/cuu/Value?bwien
Sometimes called the Winchester Wine Gallon, it was legalized in 1707 by Queen Anne, and given the definition of 231 cubic inches. It had been in use for a while as 8 pounds of wine using a merchant's pound of 7200 grains or 15 troy ounces. (The old mercantile pound had been 15 tower ounces.)
Sometimes called the Winchester Wine Gallon, it was legalized in 1707 by Queen Anne, and given the definition of 231 cubic inches. It had been in use for a while as 8 pounds of wine using a merchant's pound of 7200 grains or 15 troy ounces. (The old mercantile pound had been 15 tower ounces.)
1600 yds of "number 1 yarn" weighs a pound.
1600 yds of "number 1 yarn" weighs a pound.
Less common system used in Pennsylvania for wool yarn
Less common system used in Pennsylvania for wool yarn
In 2019, defined exactly. The triple point of water is now experimentally measured. The BIPM brochure states that "The previous definition of the kelvin set the temperature of the triple point of water, T_TPW, to be exactly 273.16 K. Due to the fact that the present definition of the kelvin fixes the numerical value of k instead of T_TPW , the latter must now be determined experimentally. At the time of adopting the present definition T_TPW was equal to 273.16 K with a relative standard uncertainty of 3.7 × 10 −7 based on measurements of k made prior to the redefinition. https://www.bipm.org/en/publications/si-brochure/
In 2019, defined exactly. The triple point of water is now experimentally measured. The BIPM brochure states that "The previous definition of the kelvin set the temperature of the triple point of water, T_TPW, to be exactly 273.16 K. Due to the fact that the present definition of the kelvin fixes the numerical value of k instead of T_TPW , the latter must now be determined experimentally. At the time of adopting the present definition T_TPW was equal to 273.16 K with a relative standard uncertainty of 3.7 × 10 −7 based on measurements of k made prior to the redefinition. https://www.bipm.org/en/publications/si-brochure/
cljdoc builds & hosts documentation for Clojure/Script libraries
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