Units – identify the CGS unit of dynamic viscosity Poise is used as the unit of viscosity in the centimetre–gram–second (CGS) system. Do you agree?

Introduction:Engineering uses both SI and legacy CGS units for viscosity. The question asks whether “poise” belongs to the CGS system and what type of viscosity it measures.

Given Data / Assumptions:

• Two viscosity types: dynamic (mu) and kinematic (nu).
• CGS base units: centimetre, gram, second.
• Common submultiples: centipoise (cP) and centistokes (cSt).

Concept / Approach:

In CGS, the unit of dynamic viscosity is poise (P), where 1 P = 1 g/(cm·s). In SI, dynamic viscosity is in Pa·s (N·s/m^2). Kinematic viscosity's CGS unit is stokes (St), 1 St = 1 cm^2/s. Therefore, it is correct to say “poise is the unit of viscosity in CGS,” with the understanding it refers to dynamic viscosity. Water at 20°C has mu ≈ 1 cP (0.01 P) and nu ≈ 1 cSt.

Step-by-Step Solution:

Verification / Alternative check:

Unit conversions: 1 P = 0.1 Pa·s; 1 cP = 1 mPa·s. These standard conversions confirm P is a CGS unit, not SI.

Why Other Options Are Wrong:

Kinematic-only or SI-only claims misidentify which viscosity and which system uses poise.Gas-only qualifier is unnecessary; units apply to any fluid.

Common Pitfalls:

Mixing up poise (dynamic) with stokes (kinematic) or reporting SI values with CGS unit names.

Final Answer:

Agree