In the CGS (centimetre–gram–second) system, the standard unit of kinematic viscosity ν is:

Introduction / Context:
Fluid property tables report viscosity in either dynamic (μ) or kinematic (ν) forms and in various unit systems. Engineers must convert correctly between SI and CGS to avoid large numerical errors in design and simulation.

Given Data / Assumptions:

• Kinematic viscosity ν = μ/ρ.
• CGS unit system is used.
• We distinguish dynamic (poise) from kinematic (stoke) viscosity units.

Concept / Approach:

In CGS, dynamic viscosity has unit poise (P) = g/(cm·s). Kinematic viscosity has unit stoke (St) = cm^2/s. Commonly, centistokes (cSt) are used in lubrication (1 cSt = 0.01 St).

Step-by-Step Solution:

Verification / Alternative check:

Water at 20°C: μ ≈ 1 cP, ρ ≈ 1 g/cm^3 ⇒ ν ≈ 1 cSt = 0.01 St, matching common reference data.

Why Other Options Are Wrong:

Poise (b) is dynamic viscosity unit. Newton and Pascal-second are SI force and SI dynamic viscosity units, respectively. “None” is unnecessary because stoke is the correct CGS kinematic viscosity unit.

Common Pitfalls:

Mixing up cSt with St; a factor of 100 error is frequent in oil selection and Reynolds number calculations.

Final Answer:

Stoke