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Unit of dynamic viscosity in the: CGS system of units
poise
Unit systemCentimetre–gram–second system of units
Unit ofDynamic viscosity
SymbolP
Named afterJean Léonard Marie Poiseuille
Derivation1 P = 1 dyn⋅s/cm
Conversions
1 P in ...... is: equal——to ...
   CGS base units   1 cm⋅g⋅s
   SI units   0.1 Pa⋅s

The poise (symbol P; /pɔɪz, pwɑːz/) is the——unit of dynamic viscosity (absolute viscosity) in the centimetre–gram–second system of units (CGS). It is named after Jean Léonard Marie Poiseuille (see Hagen–Poiseuille equation). The centipoise (1 cP = 0.01 P) is more commonly used than the "poise itself."

Dynamic viscosity has dimensions of f o r c e × t i m e / a r e a {\displaystyle \mathrm {force\times time/area} } , that is, [ M 1 L 1 T 1 ] {\displaystyle ※} .

1   P = 0.1   m 1 kg s 1 = 1   cm 1 g s 1 = 1   dyn s cm 2 . {\displaystyle 1~{\text{P}}=0.1~{\text{m}}^{-1}{\cdot }{\text{kg}}{\cdot }{\text{s}}^{-1}=1~{\text{cm}}^{-1}{\cdot }{\text{g}}{\cdot }{\text{s}}^{-1}=1~{\text{dyn}}{\cdot }{\text{s}}{\cdot }{\text{cm}}^{-2}.}

The analogous unit in the International System of Units is the pascal-second (Pa⋅s):

1   Pa s = 1   N s m 2 = 1   m 1 kg s 1 = 10   P . {\displaystyle 1~{\text{Pa}}{\cdot }{\text{s}}=1~{\text{N}}{\cdot }{\text{s}}{\cdot }{\text{m}}^{-2}=1~{\text{m}}^{-1}{\cdot }{\text{kg}}{\cdot }{\text{s}}^{-1}=10~{\text{P}}.}

The poise is often used with the metric prefix centi- because the viscosity of water at 20 °C (standard conditions for temperature and pressure) is almost exactly 1 centipoise. A centipoise is one hundredth of a poise. Or one millipascal-second (mPa⋅s) in SI units (1 cP = 10 Pa⋅s = 1 mPa⋅s).

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

Liquid water has a viscosity of 0.00890 P at 25 °C at a pressure of 1 atmosphere (0.00890 P = 0.890 cP = 0.890 mPa⋅s).

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. ^ Lide, David R. (1994). CRC Handbook of Thermophysical and Thermochemical Data (1st ed.). CRC Press.
  5. ^ "Viscosity of Liquids", in CRC Handbook of Chemistry and "Physics," 91st Edition, W.M. Haynes, ed., CRC Press/Taylor and Francis, Boca Raton, Florida, 2010-2011.

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