Understanding poises to pascal-seconds Conversion
The poise (P) is the CGS unit of dynamic viscosity, equal to one gram per centimeter-second. The pascal-second (Pa·s) is the coherent SI unit, equal to one newton-second per square meter, and it is the standard for scientific and engineering viscosity data. Because one poise is exactly one-tenth of a pascal-second, this conversion is fundamental when moving between older rheology literature and SI reporting.
Conversion Formula
To convert poises to pascal-seconds, multiply by this factor:
Step-by-Step Example
Convert 25 poises to pascal-seconds.
How to Convert poises to pascal-seconds
Translate a CGS poise viscosity into the coherent SI pascal-second.
- Take the poise value: Record the dynamic viscosity in poise.
- Multiply by 0.1: Ten poise equal one pascal-second.
- Report in Pa·s: The product is the SI viscosity value.
- Worked result: 25 P × 0.1 = 2.5 Pa·s.
poises to pascal-seconds conversion table
| poises (P) | pascal-seconds (Pa-s) |
|---|---|
| 0 | 0 |
| 1 | 0.1 |
| 2 | 0.2 |
| 3 | 0.3 |
| 4 | 0.4 |
| 5 | 0.5 |
| 6 | 0.6 |
| 7 | 0.7 |
| 8 | 0.8 |
| 9 | 0.9 |
| 10 | 1 |
| 15 | 1.5 |
| 20 | 2 |
| 25 | 2.5 |
| 30 | 3 |
| 40 | 4 |
| 50 | 5 |
| 60 | 6 |
| 70 | 7 |
| 80 | 8 |
| 90 | 9 |
| 100 | 10 |
| 150 | 15 |
| 200 | 20 |
| 250 | 25 |
| 300 | 30 |
| 400 | 40 |
| 500 | 50 |
| 600 | 60 |
| 700 | 70 |
| 800 | 80 |
| 900 | 90 |
| 1000 | 100 |
| 2000 | 200 |
| 3000 | 300 |
| 4000 | 400 |
| 5000 | 500 |
| 10000 | 1000 |
| 25000 | 2500 |
| 50000 | 5000 |
| 100000 | 10000 |
| 250000 | 25000 |
| 500000 | 50000 |
| 1000000 | 100000 |
What is the Poise?
The poise is the unit of dynamic viscosity in the centimetre-gram-second (CGS) system, measuring a fluid's resistance to shear flow. It remains common in fields such as chemistry, food science, and petroleum engineering.
Definition
One poise is the viscosity of a fluid in which a shear stress of one dyne per square centimetre produces a velocity gradient of one reciprocal second.
In SI terms, 1 poise = 0.1 Pa·s = 1 g·cm⁻¹·s⁻¹. The everyday subunit is the centipoise (cP), equal to 0.01 poise and to 1 millipascal-second, which is why water's viscosity is famously about 1 cP.
Origin and History
The poise is named after the French physician and physiologist Jean Léonard Marie Poiseuille (1797–1869), who studied the flow of liquids through narrow tubes, work later formalized as the Hagen–Poiseuille law. The unit was adopted within the CGS system in his honour.
Law and Notable Facts
The poise is not an SI unit, but it is accepted for continued use alongside SI in many industries. Its centipoise subunit is so entrenched that viscosity tables and specifications worldwide still quote values in cP even where the pascal-second is the formal standard.
Real-World Examples and Conversions
- Water at 20 °C: about 0.01 poise (1 centipoise).
- Air at room temperature: about 0.00018 poise.
- Glycerol at 20 °C: roughly 15 poise.
- 1 poise equals 0.1 Pa·s and 100 centipoise.
What is the Pascal-Second?
The pascal-second is the SI derived unit of dynamic (shear) viscosity, measuring a fluid's resistance to flow. It quantifies the shear stress needed to produce a unit velocity gradient in a fluid.
Definition
One pascal-second is the viscosity of a fluid in which a shear stress of one pascal produces a velocity gradient of one reciprocal second between adjacent layers.
Expressed in SI base units, 1 Pa·s = 1 kg·m⁻¹·s⁻¹ = 1 N·s/m². It is the coherent SI unit of dynamic viscosity and is exactly equal to 10 poise (the CGS unit), so 1 Pa·s = 1000 mPa·s = 1000 centipoise.
Origin and History
Viscosity was first characterized quantitatively through the work of Newton and later Poiseuille in the nineteenth century, with the CGS poise (named for Poiseuille) long serving as the standard unit. The pascal-second entered use with the adoption of the SI, tying viscosity directly to the pascal of pressure.
Law and Notable Facts
The pascal-second is the officially sanctioned SI unit of dynamic viscosity, though the millipascal-second (equal to the once-ubiquitous centipoise) remains far more common in practice because water at 20 °C has a viscosity of almost exactly 1 mPa·s.
Real-World Examples and Conversions
- Water at 20 °C: about 0.001 Pa·s (1 mPa·s).
- Air at room temperature: about 0.0000181 Pa·s.
- Olive oil at 20 °C: roughly 0.084 Pa·s.
- Honey: commonly 2 to 10 Pa·s depending on temperature and water content.
Frequently Asked Questions
How many pascal-seconds are in one poise?
One poise equals 0.1 pascal-second, so ten poise make one Pa·s.
Why is the pascal-second preferred in science?
It is the coherent SI unit of dynamic viscosity, keeping calculations consistent with newtons, meters, and seconds.
What is the viscosity of water in pascal-seconds?
Water at 20 °C is about 0.001 Pa·s, which equals 0.01 poise or 1 cP.
How do I convert 100 poises to pascal-seconds?
Multiply by 0.1: 100 P equals 10 Pa·s.
How does poise relate to centipoise and Pa·s together?
One poise is 100 cP and 0.1 Pa·s, so 1 Pa·s equals 1000 cP.
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Complete poises conversion table
| Unit | Result |
|---|---|
| pascal-seconds (Pa-s) | 0.1 Pa-s |
| millipascal-seconds (mPa-s) | 100 mPa-s |
| centipoises (cP) | 100 cP |
| pound-force-seconds per square foot (lbf-s/ft2) | 0.002088543 lbf-s/ft2 |
| pounds per foot-second (lb/(ft-s)) | 0.0671969 lb/(ft-s) |