Question

Poise is the unit of:
A. Pressure
B. Friction
C. Surface tension
D. Viscosity

Answer 1

Poise is a unit of centimetre-gram-second (CGS) system of units. It is commonly used in the ASTM standards as centipoise. This metric prefix centi- is used with the poise for some calculation because of the reason that the value of viscosity of the water is 1centipoise at $20^\circ C$ that is at normal temperature and pressure.

Complete step by step answer:
From the above hint we see that the centipoise is used to measure the viscosity. So obviously the poise will also be used for the measurement of the viscosity.
Hence poise is the unit of viscosity and it is a CGS (centimetre-gram-second) unit.
Also, we can find out the solution as follows,
As we all know that the viscous force for any liquid,
$F = \mu \dfrac{{dv}}{{dy}}$
Where $\mu$= coefficient of viscosity.
So, from the above equation the unit of the coefficient of viscosity will be $Pa.s$(pascal second)
And it is also termed as Decapoise. Where 1 Decapoise = 10 poise.
And we know that the coefficient of viscosity is the measure of the viscosity.
So, poise is the unit of the viscosity.

So, the correct answer is “Option D”.

Note: As we all know that the viscosity is defined as the resistance to flow of any liquid. We have discussed that the poise is a “CGS'' unit of the viscosity but the application will be limited until we don’t have a SI unit for a particular quantity. So, we should also know the SI unit of the viscosity. So the SI unit of the viscosity is pascal-second which is abbreviated as $Pa.s$ and also can be written as $kg.{m^{ - 1}}.{s^{ - 1}}$.