The poiseuille (symbol Pl ) has been proposed as a derived SI unit of dynamic viscosity , named after the French physicist Jean Léonard Marie Poiseuille (1797–1869).
35-559: In practice the unit has never been widely accepted and most international standards bodies do not include the poiseuille in their list of units. The third edition of the IUPAC Green Book , for example, lists Pa⋅s ( pascal - second ) as the SI-unit for dynamic viscosity, and does not mention the poiseuille. The equivalent CGS unit, the poise , symbol P, is most widely used when reporting viscosity measurements. Liquid water has
70-432: A ⋅ m 3 m o l K × K 1 {\displaystyle \mathrm {Pa{\cdot }m^{3}} ={\frac {\cancel {\mathrm {mol} }}{1}}\times {\frac {\mathrm {Pa{\cdot }m^{3}} }{{\cancel {\mathrm {mol} }}\ {\cancel {\mathrm {K} }}}}\times {\frac {\cancel {\mathrm {K} }}{1}}} As can be seen, when the dimensional units appearing in
105-458: A 5 °C change is the same as a 9 °F change. Thus, to convert from units of Fahrenheit to units of Celsius, one subtracts 32 °F (the offset from the point of reference), divides by 9 °F and multiplies by 5 °C (scales by the ratio of units), and adds 0 °C (the offset from the point of reference). Reversing this yields the formula for obtaining a quantity in units of Celsius from units of Fahrenheit; one could have started with
140-472: A viscosity of 0.000 890 Pl at 25 °C (77 °F) at a pressure of 1 atm ( 0.000 890 Pl = 0.008 90 P = 0.890 cP = 0.890 mPa⋅s ). This standards - or measurement -related article is a stub . You can help Misplaced Pages by expanding it . IUPAC Green Book Quantities, Units and Symbols in Physical Chemistry , also known as
175-811: Is based on published, citeable sources. Information in the Green Book is synthesized from recommendations made by IUPAC, the International Union of Pure and Applied Physics (IUPAP) and the International Organization for Standardization (ISO), including recommendations listed in the IUPAP Red Book Symbols, Units, Nomenclature and Fundamental Constants in Physics and in the ISO 31 standards. The third edition of
210-457: Is chosen based on the relationship between one of the original units and one of the desired units (or some intermediary unit), before being rearranged to create a factor that cancels out the original unit. For example, as "mile" is the numerator in the original fraction and 1 m i = 1609.344 m {\displaystyle \mathrm {1~mi} =\mathrm {1609.344~m} } , "mile" will need to be
245-478: Is especially useful for programming and/or making a worksheet , where input quantities are taking multiple different values; For example, with the factor calculated above, it is very easy to see that the healing length of Yb with chemical potential 20.3 nK is There are many conversion tools. They are found in the function libraries of applications such as spreadsheets databases, in calculators, and in macro packages and plugins for many other applications such as
280-689: Is important to point out that such 'mathematical manipulation' is neither without prior precedent, nor without considerable scientific significance. Indeed, the Planck constant , a fundamental physical constant, was 'discovered' as a purely mathematical abstraction or representation that built on the Rayleigh–Jeans law for preventing the ultraviolet catastrophe . It was assigned and ascended to its quantum physical significance either in tandem or post mathematical dimensional adjustment – not earlier. The factor–label method can convert only unit quantities for which
315-536: Is incorrect. The typographical rules are extensive, including even such detail as whether "20°C" or "20 °C" is the correct form. Section 3.8 introduces atomic units and gives a table of atomic units of various physical quantities and the conversion factor to the SI units . Section 7.3(v) gives a concise but clear tutorial on practical use of atomic units, in particular how to understand equations "written in atomic units". Factor-label method Conversion of units
350-453: Is just mathematically the same thing, multiply Z by unity, the product is still Z : For example, you have an expression for a physical value Z involving the unit feet per second ( [ Z ] i {\displaystyle [Z]_{i}} ) and you want it in terms of the unit miles per hour ( [ Z ] j {\displaystyle [Z]_{j}} ): Or as an example using
385-423: Is neither a constant difference nor a constant ratio. There is, however, an affine transform ( x ↦ a x + b {\displaystyle x\mapsto ax+b} , rather than a linear transform x ↦ a x {\displaystyle x\mapsto ax} ) between them. For example, the freezing point of water is 0 °C and 32 °F, and
SECTION 10
#1732772499143420-684: Is our factor. Now, make use of the fact that ξ ∝ 1 m μ {\displaystyle \xi \propto {\frac {1}{\sqrt {m\mu }}}} . With m = 23 Da , μ = 128 k B ⋅ nK {\displaystyle m=23\,{\text{Da}},\mu =128\,k_{\text{B}}\cdot {\text{nK}}} , ξ = 15.574 23 ⋅ 128 μm = 0.287 μm {\displaystyle \xi ={\frac {15.574}{\sqrt {23\cdot 128}}}\,{\text{μm}}=0.287\,{\text{μm}}} . This method
455-512: Is referred to as the "Livro Verde". A concise four-page summary of the most important material in the Green Book was published in the July–August 2011 issue of Chemistry International , the IUPAC news magazine. The second edition of the Green Book ( ISBN 0-632-03583-8 ) was first published in 1993. It was reprinted in 1995, 1996, and 1998. The Green Book is a direct successor of
490-400: Is the conversion of the unit of measurement in which a quantity is expressed, typically through a multiplicative conversion factor that changes the unit without changing the quantity. This is also often loosely taken to include replacement of a quantity with a corresponding quantity that describes the same physical property. Unit conversion is often easier within a metric system such as
525-554: Is usually given in daltons , instead of kilograms , and chemical potential μ is often given in the Boltzmann constant times nanokelvin . The condensate's healing length is given by: ξ = ℏ 2 m μ . {\displaystyle \xi ={\frac {\hbar }{\sqrt {2m\mu }}}\,.} For a Na condensate with chemical potential of (the Boltzmann constant times) 128 nK,
560-496: The Green Book , is a compilation of terms and symbols widely used in the field of physical chemistry . It also includes a table of physical constants , tables listing the properties of elementary particles , chemical elements , and nuclides , and information about conversion factors that are commonly used in physical chemistry. The Green Book is published by the International Union of Pure and Applied Chemistry (IUPAC) and
595-443: The Green Book ( ISBN 978-4-06-154359-1 ) was published in 2009. A French translation of the third edition of the Green Book ( ISBN 978-2-8041-7207-7 ) was published in 2012. A Portuguese translation (Brazilian Portuguese and European Portuguese) of the third edition of the Green Book ( ISBN 978-85-64099-19-7 ) was published in 2018, with updated values of the physical constants and atomic weights; it
630-399: The Green Book ( ISBN 978-0-85404-433-7 ) was first published by IUPAC in 2007. A second printing of the third edition was released in 2008; this printing made several minor revisions to the 2007 text. A third printing of the third edition was released in 2011. The text of the third printing is identical to that of the second printing. A Japanese translation of the third edition of
665-555: The Manual of Symbols and Terminology for Physicochemical Quantities and Units , originally prepared for publication on behalf of IUPAC's Physical Chemistry Division by M. L. McGlashen in 1969. A full history of the Green Book's various editions is provided in the historical introduction to the third edition. The second edition and the third edition (second printing) of the Green Book have both been made available online as PDF files;
700-534: The SI than in others, due to the system's coherence and its metric prefixes that act as power-of-10 multipliers. The definition and choice of units in which to express a quantity may depend on the specific situation and the intended purpose. This may be governed by regulation, contract , technical specifications or other published standards . Engineering judgment may include such factors as: For some purposes, conversions from one system of units to another are needed to be exact, without increasing or decreasing
735-494: The PDF version of the third edition is fully searchable. The four-page concise summary is also available online as a PDF file. External Links (below) . In addition to the obvious data on quantities, units and symbols, the compilation contains some less obvious but very useful information on related topics. Unit conversion is a notorious source of errors. Many people apply individual rules, e.g. "to obtain length in centimeters multiply
SECTION 20
#1732772499143770-532: The calculation of healing length (in micrometres) can be done in two steps: Assume that m = 1 Da , μ = k B ⋅ 1 nK {\displaystyle m=1\,{\text{Da}},\mu =k_{\text{B}}\cdot 1\,{\text{nK}}} , this gives ξ = ℏ 2 m μ = 15.574 μ m , {\displaystyle \xi ={\frac {\hbar }{\sqrt {2m\mu }}}=15.574\,\mathrm {\mu m} \,,} which
805-414: The denominator in the conversion factor. Dividing both sides of the equation by 1 mile yields 1 m i 1 m i = 1609.344 m 1 m i {\displaystyle {\frac {\mathrm {1~mi} }{\mathrm {1~mi} }}={\frac {\mathrm {1609.344~m} }{\mathrm {1~mi} }}} , which when simplified results in
840-550: The desired unit [ Z ] j {\displaystyle [Z]_{j}} , e.g. if [ Z ] i = c i j × [ Z ] j {\displaystyle [Z]_{i}=c_{ij}\times [Z]_{j}} , then: Now n i {\displaystyle n_{i}} and c i j {\displaystyle c_{ij}} are both numerical values, so just calculate their product. Or, which
875-433: The dimensionless 1 = 1609.344 m 1 m i {\displaystyle 1={\frac {\mathrm {1609.344~m} }{\mathrm {1~mi} }}} . Because of the identity property of multiplication, multiplying any quantity (physical or not) by the dimensionless 1 does not change that quantity. Once this and the conversion factor for seconds per hour have been multiplied by
910-448: The equation. Having the same units on both sides of an equation does not ensure that the equation is correct, but having different units on the two sides (when expressed in terms of base units) of an equation implies that the equation is wrong. For example, check the universal gas law equation of PV = nRT , when: P a ⋅ m 3 = m o l 1 × P
945-524: The equivalence between 100 °C and 212 °F, which yields the same formula. Hence, to convert the numerical quantity value of a temperature T [F] in degrees Fahrenheit to a numerical quantity value T [C] in degrees Celsius, this formula may be used: To convert T [C] in degrees Celsius to T [F] in degrees Fahrenheit, this formula may be used: Starting with: replace the original unit [ Z ] i {\displaystyle [Z]_{i}} with its meaning in terms of
980-435: The length in inches by 2.54", but combining several such conversions is laborious and prone to mistakes. A better way is to use the factor-label method , which is closely related to dimensional analysis , and quantity calculus explained in sections 1.1 and 7.1 of this compilation. Section 1.3 explains the rules for writing scientific symbols and names, for example, where to use capital letters or italics, and where their use
1015-430: The metric system, you have a value of fuel economy in the unit litres per 100 kilometres and you want it in terms of the unit microlitres per metre : In the cases where non- SI units are used, the numerical calculation of a formula can be done by first working out the factor, and then plug in the numerical values of the given/known quantities. For example, in the study of Bose–Einstein condensate , atomic mass m
1050-858: The numerator and denominator of any of the fractions can be cancelled out until only the desired set of dimensional units is obtained. For example, 10 miles per hour can be converted to metres per second by using a sequence of conversion factors as shown below: 10 m i 1 h × 1609.344 m 1 m i × 1 h 3600 s = 4.4704 m s . {\displaystyle {\frac {\mathrm {10~{\cancel {mi}}} }{\mathrm {1~{\cancel {h}}} }}\times {\frac {\mathrm {1609.344~m} }{\mathrm {1~{\cancel {mi}}} }}\times {\frac {\mathrm {1~{\cancel {h}}} }{\mathrm {3600~s} }}=\mathrm {4.4704~{\frac {m}{s}}} .} Each conversion factor
1085-452: The numerator and denominator of the equation's right hand side are cancelled out, both sides of the equation have the same dimensional units. Dimensional analysis can be used as a tool to construct equations that relate non-associated physico-chemical properties. The equations may reveal undiscovered or overlooked properties of matter, in the form of left-over dimensions – dimensional adjusters – that can then be assigned physical significance. It
Poiseuille - Misplaced Pages Continue
1120-448: The numerators and the denominators of the fractions in the above equation, the NO x concentration of 10 ppm v converts to mass flow rate of 24.63 grams per hour. The factor–label method can also be used on any mathematical equation to check whether or not the dimensional units on the left hand side of the equation are the same as the dimensional units on the right hand side of
1155-449: The original fraction to cancel out the units mile and hour , 10 miles per hour converts to 4.4704 metres per second. As a more complex example, the concentration of nitrogen oxides ( NO x ) in the flue gas from an industrial furnace can be converted to a mass flow rate expressed in grams per hour (g/h) of NO x by using the following information as shown below: After cancelling any dimensional units that appear both in
1190-510: The precision of the expressed quantity. An adaptive conversion may not produce an exactly equivalent expression. Nominal values are sometimes allowed and used. The factor–label method , also known as the unit–factor method or the unity bracket method , is a widely used technique for unit conversions that uses the rules of algebra . The factor–label method is the sequential application of conversion factors expressed as fractions and arranged so that any dimensional unit appearing in both
1225-644: The units are in a linear relationship intersecting at 0 ( ratio scale in Stevens's typology). Most conversions fit this paradigm. An example for which it cannot be used is the conversion between the Celsius scale and the Kelvin scale (or the Fahrenheit scale ). Between degrees Celsius and kelvins, there is a constant difference rather than a constant ratio, while between degrees Celsius and degrees Fahrenheit there
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