Correct Answer - Option 2 : Dynamic viscosity is independent of pressure
Explanation:
Viscosity: The property that represents the internal resistance of a fluid to motion (i.e. fluidity) is called viscosity. There are two ways to write viscosities:
(1) Dynamic viscosity: This is also termed as absolute viscosity. A common unit of dynamic viscosity is poise.
1 poise = 0.1 Pa.s = 0.1 N.s/m2
Dynamic viscosity is a function of temperature only.
(2) Kinematic Viscosity: The ratio of dynamic viscosity to density appears frequently and this ratio is given by the name kinematic viscosity. Its unit is m2/s.
Kinematic Viscosity is a function of temperature and pressure.
∴ C.G.S unit of kinematic viscosity is cm2/s or, Stoke. (1 stoke = 0.0001 m2/s)
Variation of viscosity with temperature:
(i) Increase in temperature causes a decrease in the viscosity of a liquid, whereas the viscosity of gases increases with temperature growth.
(ii) The reason for the above phenomenon is that; in liquids; viscosity is primarily due to molecular cohesion which decreases with increases in volume due to temperature increment, while in gases, viscosity is due to molecular momentum transfer which increases with increases in number of collision between gas and molecule.
