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Fluids Final (All multiple choice!)

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10:
Consider a rectangular channel 3 m wide laid on a 1° slope. If the water depth is 2 m, the hydraulic radius is:
(a) 0.43 m, (b) 0.6 m, (c) 0.86 m, (d) 1.0 m, (e) 1.2 m
C
For the channel of Prob. FE10.1, the most efficient water depth (best flow for a given slope and resistance) is
(a) 1 m, (b) 1.5 m, (c) 2 m, (d) 2.5 m, (e) 3 m

Consider a rectangular channel 3 m wide laid on a 1° slope. If the water depth is 2 m, the hydraulic radius is 0.86 m.
B
If the channel of Prob. FE10.1 is built of rubble cement (Manning's n ≈ 0.020), what is the uniform flow rate when the water depth is 2 m?
(a) 6 m3/s, (b) 18 m3/s, (c) 36 m3/s, (d) 40 m3/s, (e) 53 m3/s

Consider a rectangular channel 3 m wide laid on a 1° slope. If the water depth is 2 m, the hydraulic radius is 0.86 m.
C
For the channel of Prob. FE10.1, if the water depth is 2 m and the uniform flow rate is 24 m3/s, what is the approximate value of Manning's roughness factor n?
(a) 0.015, (b) 0.020, (c) 0.025, (d) 0.030, (e) 0.035

Consider a rectangular channel 3 m wide laid on a 1° slope. If the water depth is 2 m, the hydraulic radius is 0.86 m.
D
For the channel of Prob. FE10.1, if Manning's roughness factor n ≈ 0.020 and Q ≈ 29 m3/s, what is the normal depth yn?
(a) 1 m, (b) 1.5 m, (c) 2 m, (d) 2.5 m, (e) 3 m

Consider a rectangular channel 3 m wide laid on a 1° slope. If the water depth is 2 m, the hydraulic radius is 0.86 m.
B
For the channel of Prob. FE10.1, if Q ≈ 24 m3/s, what is the critical depth yc?
(a) 1.0 m, (b) 1.26 m, (c) 1.5 m, (d) 1.87 m, (e) 2.0 m

Consider a rectangular channel 3 m wide laid on a 1° slope. If the water depth is 2 m, the hydraulic radius is 0.86 m.
D
For the channel of Prob. FE10.1, if Q ≈ 24 m3/s and the depth is 2 m, what is the Froude number of the flow?
(a) 0.50, (b) 0.77, (c) 0.90, (d) 1.00, (e) 1.11

Consider a rectangular channel 3 m wide laid on a 1° slope. If the water depth is 2 m, the hydraulic radius is 0.86 m.
C
Chapter 1:
The absolute viscosity µ of a fluid is primarily a function of
a. Density
b. Temperature
c. Pressure
d. Velocity
e. Surface tension
B
Chapter 1:
Carbon dioxide, at 20°C and 1 atm, is compressed isentropically to 4 atm. Assume CO2 is an ideal gas. The final temperature would be
a. 130°C
b. 162°C
c. 171°C
d. 237°C
e. 313°C
a
Chapter 1:

Helium has a molecular weight of 4.003. What is the weight of 2 m3 of helium at 1 atm and 20°C?
a. 3.3 N
b. 6.5 N
c. 11.8 N
d. 23.5 N
e. 94.2 N
a
Chapter 1:
An oil has a kinematic viscosity of 1.25 E-4 m2/s and a specific gravity of 0.80. What is its dynamic (absolute) viscosity in kg/(m ∙ s)?
a. 0.08
b. 0.10
c. 0.125
d. 1.0
e. 1.25
b
Chapter 1:
Consider a soap bubble of diameter 3 mm. If the surface tension coefficient is 0.072 N/m and external pressure is 0 Pa gage, what is the bubble's internal gage pressure?
a. −24 Pa
b. +48 Pa
c. +96 Pa
d. +192 Pa
e. −192 Pa
d
Chapter 1:
The only possible dimensionless group that combines velocity V, body size L, fluid density ρ, and surface tension coefficient σ is
a. Lρσ/V
b. ρVL2/σ
c. ρσV2/L
d. σLV2/ρ
e. ρLV2/σ
e
Chapter 1:
Two parallel plates, one moving at 4 m/s and the other fixed, are separated by a 5-mm-thick layer of oil of specific gravity 0.80 and kinematic viscosity 1.25 E-4 m2/s. What is the average shear stress in the oil?
a. 80 Pa
b. 100 Pa
c. 125 Pa
d. 160 Pa
e. 200 Pa
a
Chapter 1:
Carbon dioxide has a specific heat ratio of 1.30 and a gas constant of 189 J/(kg ∙ °C). If its temperature rises from 20 to 45°C, what is its internal energy rise?
a. 12.6 kJ/kg
b. 15.8 kJ/kg
c. 17.6 kJ/kg
d. 20.5 kJ/kg
e. 25.1 kJ/kg
b
Chapter 1:
A certain water flow at 20°C has a critical cavitation number, where bubbles form, Ca ≈ 0.25, where Ca = 2(pa− pvap)/ρV2. If pa = 1 atm and the vapor pressure is 0.34 pounds per square inch absolute (psia), for what water velocity will bubbles form?
a. 12 mi/h
b. 28 mi/h
c. 36 mi/h
d. 55 mi/h
e. 63 mi/h
e
Chapter 1:
Example 1.10 gave an analysis that predicted that the viscous moment on a rotating disk M = π µΩR4/(2h). If the uncertainty of each of the four variables (µ, Ω, R, h) is 1.0 percent, what is the estimated overall uncertainty of the moment M?
4.0 percent
4.4 percent
5.0 percent
6.0 percent
7.0 percent

A certain water flow at 20°C has a critical cavitation number, where bubbles form, Ca ≈ 0.25, where Ca = 2(pa− pvap)/ρV2. If pa = 1 atm and the vapor pressure is 0.34 pounds per square inch absolute (psia). The velocity in which bubbles will form is 63 mi/hr.
b
Chapter 2:
A gage attached to a pressurized nitrogen tank reads a gage pressure of 28 in of mercury. If atmospheric pressure is 14.4 psia, what is the absolute pressure in the tank?
a. 95 kPa
b. 99 kPa
c. 101 kPa
d. 194 kPa
e. 203 kPa
d
Chapter 2:
On a sea-level standard day, a pressure gage, moored below the surface of the ocean (SG = 1.025), reads an absolute pressure of 1.4 MPa. How deep is the instrument?
a. 4 m
b. 129 m
c. 133 m
d. 140 m
e. 2080 m
b
Chapter 2:
In Fig. FE2.3, if the oil in region B has SG = 0.8 and the absolute pressure at point A is 1 atm, what is the absolute pressure at point B?

a. 5.6 kPa

b. 10.9 kPa

c 107 kPa

d. 112 kPa

e. 157 kPa
c
Chapter 2:
In Fig. FE2.3, if the oil in region B has SG = 0.8 and the absolute pressure at point B is 14 psia, what is the absolute pressure at point A?

a. 11 kPa

b. 41 kPa

c. 86 kPa

d. 91 kPa

e. 101 kPa
d
Chapter 2:
A tank of water (SG = 1.0) has a gate in its vertical wall 5 m high and 3 m wide. The top edge of the gate is 2 m below the surface. What is the hydrostatic force on the gate?

a. 147 kN

b. 367 kN

c. 490 kN

d. 661 kN, (e) 1028 kN
d
Chapter 2:
In Prob. FE2.5, how far below the surface is the center of pressure of the hydrostatic force?

a. 4.50 m

b. 5.46 m

c. 6.35 m

d. 5.33 m

e. 4.96 m


A tank of water (SG = 1.0) has a gate in its vertical wall 5 m high and 3 m wide. The top edge of the gate is 2 m below the surface.
e
Chapter 2:
A solid 1-m-diameter sphere floats at the interface between water (SG = 1.0) and mercury (SG = 13.56) such that 40 percent is in the water. What is the specific gravity of the sphere?

a. 6.02

b. 7.28

c. 7.78

d. 8.54

e. 12.56
d
Chapter 2:
A 5-m-diameter balloon contains helium at 125 kPa absolute and 15°C, moored in sea-level standard air. If the gas constant of helium is 2077 m2/(s2 ·K) and balloon material weight is neglected, what is the net lifting force of the balloon?

a. 67 N

b. 134 N

c. 522 N

d. 653 N

e. 787 N
d
Chapter 2:
A square wooden (SG = 0.6) rod, 5 cm by 5 cm by 10 m long, floats vertically in water at 20°C when 6 kg of steel (SG = 7.84) are attached to one end. How high above the water surface does the wooden end of the rod protrude?

a. 0.6 m

b. 1.6 m

c. 1.9 m

d. 2.4 m

e. 4.0 m
c
Chapter 2:
A floating body will be stable when its

a. center of gravity is above its center of buoyancy

b. center of buoyancy is below the waterline

c. center of buoyancy is above its metacenter

d. metacenter is above its center of buoyancy

e. metacenter is above its center of gravity.
e