Question

In SI system the unit of dynamic viscosity is
1. N-s/m²
2. N-m/s²
3. Stoke
4. Poise

Answer 1

Correct Answer - Option 1 : N-s/m²

Explanation:

Viscosity: The property that represents the internal resistance of a fluid to motion (i.e. fluidity) is called viscosity. There are two types of viscosity:

Dynamic viscosity: It is the property of a fluid which offers resistance to the movement of one layer of fluid over an adjacent layer of the fluid.

• Its SI unit is N-s/m2 or Pa-s.
• Its C.G.S unit is Poise.
• 1 Poise = 0.1 Pa-s = 0.1 Ns/m2 

Kinematic Viscosity: The ratio of dynamic viscosity to density appears frequently and this ratio is given by the name kinematic viscosity.

\({\rm{Kinematic\;Viscosity\;}}\left( {\rm{\gamma }} \right) = {\rm{\;}}\frac{{{\rm{Dynamic\;viscosity\;}}\left( {\rm{\mu }} \right)}}{{{\rm{density\;}}\left( {\rm{\rho }} \right)}}\)

• Its SI unit  = m²/s.
• Its C.G.S unit = Stoke or cm²/s.
• 1 Stoke = 10-4 m2/s.