What term measures a fluid's resistance to shear and deformation, i.e., its resistance to flowing?

What term measures a fluid's resistance to shear and deformation, i.e., its resistance to flowing?

• A. Viscosity
• B. Density
• C. Pressure
• D. Specific Gravity

Answer: (A)

Viscosity is the fluid property that describes how much internal friction the fluid has when layers try to slide past each other. It is the measure of resistance to shear and deformation, which is exactly what governs how easily a fluid flows under a given driving force. When a fluid has high viscosity, its internal friction is large, so it resists flowing and behaves like a thick, slower-moving liquid (think honey). When viscosity is low, the fluid flows readily (like water or air). The mathematical relation in Newtonian fluids shows this resistance as shear stress being proportional to the velocity gradient, with viscosity as the proportionality constant (tau = mu * du/dy). This distinguishes viscosity from density (mass per volume), pressure (a driving force within a fluid element), and specific gravity (density relative to water).

Viscosity is the fluid property that describes how much internal friction the fluid has when layers try to slide past each other. It is the measure of resistance to shear and deformation, which is exactly what governs how easily a fluid flows under a given driving force. When a fluid has high viscosity, its internal friction is large, so it resists flowing and behaves like a thick, slower-moving liquid (think honey). When viscosity is low, the fluid flows readily (like water or air). The mathematical relation in Newtonian fluids shows this resistance as shear stress being proportional to the velocity gradient, with viscosity as the proportionality constant (tau = mu * du/dy). This distinguishes viscosity from density (mass per volume), pressure (a driving force within a fluid element), and specific gravity (density relative to water).