Mechanics of Fluids, 5th Edition Chapter 5: The Differential Forms of the

Fundamental Laws

14

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Sections 5.1 and 5.2

1. Which of the following conditions is never a boundary condition in fluid mechanics?

(A) The velocity is zero at a boundary

(B) The normal component of velocity is zero in an inviscid flow at a boundary

(C) The tangential component of velocity is zero in an inviscid flow at a boundary

(D) The pressure is zero at a boundary

2. What four equations provide for the four unknowns u, v, w, p that are most often of interest in

fluid mechanics?

(A) Continuity, momentum

(B) Continuity, momentum, energy

(C) Continuity, momentum, energy, equation of state

(D) Continuity, momentum, energy, enthalpy relation

3. If the x-component of velocity u depends only on y in a plane incompressible flow, the

y-component of velocity v is:

(A) ( )f y

(B) const

(C) ( )f x

(D) 0

4. Three measurements are made of the x-component velocity in the diffuser of an

incompressible plane flow to be 32 m/s, 28 m/s and 20 m/s. The measurement points are

along the centerline of the symmetrical diffuser and are 4 cm apart. The y-component of the

velocity 2 cm above the centerline is approximated to be:

(A) 2 m/s

(B) 3 m/s

(C) 4 m/s

(D) 5 m/s

Mechanics of Fluids, 5th Edition Chapter 5: The Differential Forms of the

Fundamental Laws

15

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Section 5.3

1. If the stress component

σxx is given by 2 /xx p u x

σ

μ= − + ∂ ∂ , the incompressible fluid is:

(A) Linear and isotropic

(B) Isotropic and homogeneous

(C) Linear and homogeneous

(D) Linear, isotropic, and homogeneous

2. Euler’s equation integrated along a streamline results in Bernoulli’s equation provided the

flow is:

(A) Incompressible, inviscid, steady, in an inertial reference frame

(B) Constant density, steady, along a streamline, in an inertial reference frame

(C) Incompressible, steady, along a streamline, in an inertial reference frame

(D) Constant density, steady, along a streamline, inviscid, in an inertial reference frame

3. Air is flowing straight toward a building. What expression would provide ∂p/∂x if x is

measured perpendicular to the building? Neglect viscous and gravity effects and assume

steady flow.

(A) / ( / / )p x u u x v v y

ρ∂ ∂ = − ∂ ∂ − ∂ ∂

(B) / /p x u u x

ρ∂ ∂ = − ∂ ∂

(C) / /p x v u x

ρ∂ ∂ = − ∂ ∂

(D) / ( / / )p x u u x v u y

ρ∂ ∂ = − ∂ ∂ − ∂ ∂

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