Stokes (unit)

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Physical unit
Unit name	Stokes
Unit symbol	${\displaystyle \mathrm {St} }$
Physical quantity (s)	kinematic viscosity
Formula symbol	${\displaystyle \nu }$
dimension	${\displaystyle {\mathsf {L^{2}\;T^{-1}}}}$
system	CGS system of units
In SI units	${\displaystyle \mathrm {1\,St=10^{-4}\;{\frac {m^{2}}{s}}} }$
In CGS units	${\displaystyle \mathrm {1\,St=1\;{\frac {cm^{2}}{s}}} }$
Named after	George Gabriel Stokes
Derived from	Centimeter , second

Stokes ( St ) is the name of the unit cm² / s of the kinematic viscosity in the CGS system of units ; it is named after the Irish mathematician and physicist George Gabriel Stokes . Between 1920 and 1940 the unit was also known as the Lentor .

In business transactions in Germany, the SI unit m² / s has been mandatory since 1978 . In practice, the specification in cSt (centistokes) is common.

Conversion:

${\displaystyle \mathrm {1\,St=1\,{\frac {cm^{2}}{s}}=10^{-4}\,{\frac {m^{2}}{s}}} }$

${\displaystyle \mathrm {1\,cSt=1\,{\frac {mm^{2}}{s}}=10^{-6}\,{\frac {m^{2}}{s}}} }$

The Stokes was declared a legal measure in Austria under the name Stok by federal law of July 5, 1950; In 1973 the name was changed to Stokes; since 1988 it is no longer a legal entity.

The unit name Stok was also recommended in the German standard DIN 1342 "Toughness" from August 1936.

Individual evidence

1. ^ François Cardarelli: Scientific Unit Conversion. A Practical Guide to Metrication , Springer Verlag, London 1997, p. 231.
2. ↑ Federal Law Gazette No. 174 (1973)
3. ↑ Federal Law Gazette No. 742 (1988)