Identify the correct SI unit — the unit of kinematic viscosity (ν) is:

Introduction / Context:
Kinematic viscosity ν characterizes momentum diffusion in a fluid independent of density. It is widely used in the Reynolds number and laminar-turbulent transition criteria for internal and external flows.

Given Data / Assumptions:

• Kinematic viscosity ν = μ / ρ, where μ is dynamic viscosity and ρ is density.
• SI base units: metre (m), kilogram (kg), second (s).

Concept / Approach:

Dynamic viscosity has SI units Pa·s (equivalently N·s/m²). Dividing by density (kg/m³) yields units of m²/s. Therefore, ν must be expressed in square metres per second in SI. In CGS, the unit is stokes (cm²/s).

Step-by-Step Solution:

Verification / Alternative check (if short method exists):

Use dimensional analysis: L²/T as required to make Reynolds number Re = v * L / ν dimensionless.

Why Other Options Are Wrong:

N·s/m² and Pa·s are units of dynamic viscosity μ; N·s/m³ and kg·s/m² are dimensionally incorrect for ν.

Common Pitfalls (misconceptions, mistakes):

Confusing dynamic and kinematic viscosity; mixing SI with CGS units (stoke vs m²/s).

Final Answer:

m²/sec