Poise (unit)
Unit of dynamic viscosity in the CGS system of units
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 
![[{\mathsf {M}}^{1}{\mathsf {L}}^{-1}{\mathsf {T}}^{-1}]](https://wikimedia.org/api/rest_v1/media/math/render/svg/e4e00a7e8b4e08a7fb7e609f10ea7f577adf8feb)
The analogous unit in the International System of Units is the pascal-second (Pa⋅s):
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 = 10−3 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).
Sources and credits
This article is adapted from the Wikipedia article “Poise (unit)”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Viscometer Brookfield.jpg by Samuele Madini, CC BY-SA 4.0
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