SSC JE Civil Engineering 23 Mar 2021 Shift 1 Paper

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 $\mathrm{N\text{-}s}/\mathrm{m}^{2}$ or $\mathrm{Pa\text{-}s}$. ● Its C.G.S unit is Poise. ● 1 Poise $=0.1 \mathrm{Pa\text{-}s}=0.1 \mathrm{Ns}/\mathrm{m}^{2}$ Kinematic Viscosity: The ratio of dynamic viscosity to density appears frequently and this ratio is given by the name kinematic viscosity. Kinematic Viscosity $(\gamma)=\frac{\text{Dynamic viscosity}(\mu)}{\text{density}(\rho)}$ ● Its SI unit $=\mathrm{m}^{2}/\mathrm{s}$. ● Its C.G.S unit $=$ Stoke or $\mathrm{cm}^{2}/\mathrm{s}$. ● 1 Stoke $=10^{-4} \mathrm{m}^{2}/\mathrm{s}$.