Jump to content

Poise (unit): Difference between revisions

From Wikipedia, the free encyclopedia
Content deleted Content added
added dyne equation
added standard SI units of Newtons conversion
Line 6: Line 6:
The analogous unit in the [[SI|International System of Units]] is the [[pascal-second]] (Pa·s):<ref>{{cite book|last1=Reid|first1=Robert C.|title=The Properties of Gases and Liquids.|date=1987|publisher=McGraw-Hill|edition=4th}}</ref>
The analogous unit in the [[SI|International System of Units]] is the [[pascal-second]] (Pa·s):<ref>{{cite book|last1=Reid|first1=Robert C.|title=The Properties of Gases and Liquids.|date=1987|publisher=McGraw-Hill|edition=4th}}</ref>


:<math>1~\text{Pa} \cdot \text{s} = 1~\text{kg} \cdot \text{m}^{-1} \cdot \text{s}^{-1} = 10~\text{P}.</math>
:<math>1~\text{Pa} \cdot \text{s} = 1~\text{N} \cdot \text{s} \cdot \text{m}^{-2} = 1~\text{kg} \cdot \text{m}^{-1} \cdot \text{s}^{-1} = 10~\text{P}.</math>


The poise is often used with the [[metric prefix]]<!--NB: not an SI prefix here--> ''centi-'' because the viscosity of water at 20&nbsp;°C is almost exactly 1 centipoise.<ref>{{cite book|last1=Parker|first1=Sybil P.|title=Fluid Mechanics Source Book.|date=1988|publisher=McGraw-Hill|edition=1st}}</ref> A '''centipoise''' is one hundredth of a poise, equal to one millipascal-second (mPa·s) in SI units (1 cP = 10<sup>−3</sup> Pa·s = 1 mPa·s).
The poise is often used with the [[metric prefix]]<!--NB: not an SI prefix here--> ''centi-'' because the viscosity of water at 20&nbsp;°C is almost exactly 1 centipoise.<ref>{{cite book|last1=Parker|first1=Sybil P.|title=Fluid Mechanics Source Book.|date=1988|publisher=McGraw-Hill|edition=1st}}</ref> A '''centipoise''' is one hundredth of a poise, equal to one millipascal-second (mPa·s) in SI units (1 cP = 10<sup>−3</sup> Pa·s = 1 mPa·s).

Revision as of 21:42, 7 August 2017

The poise (symbol P; English: /ˈpɔɪzˌˈpwɑːz/) is the unit of dynamic viscosity (absolute viscosity) in the centimetre–gram–second system of units.[1] It is named after Jean Léonard Marie Poiseuille.

The analogous unit in the International System of Units is the pascal-second (Pa·s):[2]

The poise is often used with the metric prefix centi- because the viscosity of water at 20 °C is almost exactly 1 centipoise.[3] A centipoise is one hundredth of a poise, equal to one millipascal-second (mPa·s) in SI units (1 cP = 10−3 Pa·s = 1 mPa·s).

The CGS symbol for the centipoise is cP. The abbreviations cps, cp, and cPs are sometimes seen.

Water has a viscosity of 0.00899 poises at 25 °C and a pressure of 1 atmosphere (0.00899 P = 0.899cP = 0.899 mPa·s).[4]

See also

References

  1. ^ Gooch, Jan W. (2010). Encyclopedia dictionary of polymers (2nd ed.). Berlin: Springer. ISBN 978-1-4419-6246-1.
  2. ^ Reid, Robert C. (1987). The Properties of Gases and Liquids (4th ed.). McGraw-Hill.
  3. ^ Parker, Sybil P. (1988). Fluid Mechanics Source Book (1st ed.). McGraw-Hill.
  4. ^ "Viscosity of Liquids", in CRC Handbook of Chemistry and Physics, 89th Edition (Internet Version 2009), David R. Lide, ed., CRC Press/Taylor and Francis, Boca Raton, FL.