Viscous shear in fluids: When two adjacent fluid layers separated by dy have a relative velocity dv, the resulting shear stress τ = μ * (dv/dy). The symbol μ is commonly called what?

Introduction / Context:

Newton’s law of viscosity defines the proportionality between shear stress and velocity gradient in a Newtonian fluid. Different textbooks use synonymous terms for μ, which can confuse learners during exams and practice.

Given Data / Assumptions:

• Newtonian fluid behavior: τ = μ * (dv/dy).
• Small deformations and steady shear.

Concept / Approach:

The parameter μ has SI units Pa·s (N·s/m^2). It is referred to by several equivalent names: dynamic viscosity, absolute viscosity, coefficient of viscosity, or simply viscosity. The term “kinematic viscosity” (ν = μ/ρ) is different and has units m^2/s.

Step-by-Step Solution:

Verification / Alternative check:

Standards (e.g., SI) give μ in Pa·s; handbooks equate “absolute” and “dynamic” to avoid confusion with kinematic viscosity.

Why Other Options Are Wrong:

• Individually, each of A–D is acceptable; the comprehensive correct choice is “All of the above”.

Common Pitfalls:

• Confusing dynamic viscosity μ with kinematic viscosity ν.

Final Answer:

All of the above