Viscosity – property governing resistance to flow The property of a liquid that controls its resistance to deformation and thus its rate of flow is called viscosity. True or false?

Introduction:
Viscosity quantifies internal friction in fluids. It influences velocity profiles, pressure drops, and energy losses in pipelines and open channels.

Given Data / Assumptions:

• Continuum fluid behavior; temperature affects viscosity but definition remains.
• Flow may be laminar or turbulent; viscosity is relevant in both regimes (e.g., laminar friction factor depends solely on Re).
• Newtonian behavior assumed for simple constitutive relation tau = mu * (du/dy).

Concept / Approach:
Dynamic viscosity mu links shear stress tau to velocity gradient. Higher mu means greater resistance to shear, slowing the rate at which layers slide past each other and thus controlling how readily the liquid flows under a given driving head.

Step-by-Step Solution:
1) Recognize that for laminar pipe flow, Δp ∝ mu * L * Q / (R^4), showing direct proportionality to mu.2) For a given pressure drop, increasing mu reduces Q (rate of flow).3) Therefore viscosity governs the ease/difficulty of flow.

Verification / Alternative check:
Compare water (low mu) with glycerin or oils (high mu): under the same head, water flows much more readily, consistent with the definition.

Why Other Options Are Wrong:

• False or restricted cases: viscosity remains the controlling property, though non-Newtonian liquids need generalized relations.
• Density primarily affects inertia and hydrostatics, not shear resistance at a given gradient.

Common Pitfalls:
Confusing dynamic (mu) with kinematic viscosity (nu = mu / rho); overlooking strong temperature dependence.

Final Answer:
True