Chapter 7, Problem 7.20P

(a)

Interpretation Introduction

Interpretation:

The value of shear stress that is exerted on the fluid under the given conditions is to be calculated.

Concept Introduction:

Newton’s law of viscosity is defined as:

  ${\tau }_{yx}=\mu \frac{d{v}_x}{dy}$  ........(1)

Here, ${\tau }_{yx}$ is shear stress in y-x direction, $\mu$ is the viscosity of the fluid, and $\frac{d{v}_x}{dy}$ is the shear strain.

(b)

Interpretation Introduction

Interpretation:

The value of force applied on the upper plate on the fluid is to be determined.

Concept Introduction:

The relationship between the average shear stress $\left(\tau \right)$ , the force applied on the fluid $\left(F\right)$ , and the cross sectional area $\left(A\right)$ to which the perpendicular force is applied is:

  $F=\tau A$  ........(2)