1. ENT 257: MULTIPLE CHOICE QUESTIONS

2. MULTIPLE CHOICE QUESTIONS(Contd)
1. The absolute viscosity μ of a fluid is primarily a function of:
(a) Density (b) temperature (c) pressure (d) velocity
2. An oil has a kinematic viscosity of 1.25E-4 m2/s and a specific gravity of What is the dynamic viscosity in N-s/m2 units?
(a) 0.08 N-s/m2 (b) 0.10 N-s/m2 (c) N-s/m2 (d) 1.0 N-s/m2
3. On a sea-level standard day, a pressure gauge moored below the surface of the ocean (SG = 1.025), reads an absolute pressure of 1.4 MPa. How deep is this instrument?
4 m (b) 129 m (c) 133 m (d) 140 m
4. The absolute pressure at point B of this manometer is 1 atm. What is the absolute pressure at point A?
(a) 5.6 kPa (b) 10.9 kPa (c) 107 kPa (d) 112 kPa

3. MULTIPLE CHOICE QUESTIONS(Contd)
5. A tank of water (SG = 1.0) has a 5-m-high and 3-m-wide gate in its wall. The top edge of this gate is 2 m below the water surface. What is the hydrostatic force acting on this gate?
(a) 147 kN (b) 367 kN (c) 490 kN (d) 661 kN
6. A 6-m-wide by 4-m-high flat rectangular gate serves to hold back water as shown here. What is the depth of the center of pressure of this gate?
4.20 m (b) 4.41 m (c) 4.63 m (d) 4.72 m
7. If a uniform solid body weighs 50 N in air and 30 N in water, its specific gravity is:
(a) (b) (c) (d) 3.00
8. A floating body is stable when its:
(a) metacenter is above its center of gravity (b) center of gravity is above its center of buoyancy
(c) center of buoyancy is below its water line (d) center of buoyancy is above its metacenter
9. A 5-m-diameter balloon containing helium at 125 kPa absolute and 15 0C is moored in standard sea-level air. If the gas constant of helium is 2077 m2/(s2-K) and the balloon material weight is neglected, what is the net lifting force of the balloon?
(a) 67 N (b) 134 N (c) 653 N (d) 787 N

4. MULTIPLE CHOICE QUESTIONS(Contd)
10. Water at 20 0C (ρ = 998 kg/m3, μ = 1E-3 N-s/m2) flows at 3 m3/h through a 3-cm-diameter orifice in a 6-cm-diameter pipe. Estimate the expected pressure drop across this flow meter.
(a) 440 Pa (b) 680 Pa (c) 875 Pa (d) 1750 Pa
11. A fireboat pump delivers water to a 4-cm-diameter nozzle through a 12-cm-diameter pipe as shown here. If friction is neglected, and the gauge pressure at section (1) is 51 kPa, what is the water flow rate?
(a) 187 gal/min (b) 199 gal/min (c) 214 gal/min (d) 359 gal/min
12. This 4-cm-diameter jet is supplied water from a 7-cm-diameter pipe at a rate of 160 gal/min. When the atmospheric pressure is 101 kPa, what is the average velocity in the water supply line?
0.81 m/s (b) 1.62 m/s (c) 2.62 m/s (d) 23 m/s

5. MULTIPLE CHOICE QUESTIONS(Contd)
13. This 3-cm-diameter water jet produces a force of 23 N on this plate when it strikes the plate. What is the average velocity of the water in the jet?
2.85 m/s (b) 5.7 m/s (c) 8.1 m/s (d) 23 m/s
14. Given the parameters V,L,g,ρ, and μ which affect a certain liquid flow problem, the ratio V2/Lg is usually known as the:
Velocity head (b) Bernoulli head (c) Froude number (d) Impact energy
15. Consider a liquid with density ρ, viscosity μ, and velocity V flowing over a very small dam spillway of length L, such that the surface tension coefficient σ is very important. The quantity ρV2L/σ in this case is important and is called the:
Weber number (b) Froude number (c) Prandtl number (d) Bond number
16. For the flow of water at a Reynolds number of 1.03E6 through a 5-cm-diameter pipe of roughness height 0.5 mm, the approximate Darcy friction factor is:
(a) (b) (c) (d) 0.049

6. MULTIPLE CHOICE QUESTIONS(Contd)
17. Sea-level standard air (ρ = 1.22 kg/m3) blows over an 18-m by 20-cm-diameter flag pole at 75 km/h. The drag coefficient, based on the frontal area is Estimate the wind-induced bending moment at the base of the pole.
9.7 kN-m (b) 15.2 kN-m (c) 22.5 kN-m (d) kN-m
18. The only possible dimensionless group that combines velocity V, body size L, fluid density ρ, and surface tension coefficient σ is:
Lρσ/V (b) ρVL2/σ (c) σLV2/ρ (d) ρLV2/σ
19. Two parallel plates, one moving at 4 m/s and the other stationary, are separated by a 5-mm-thick layer of oil with specific gravity 0.8 and kinematic viscosity 1.25E-4 m2/s. What is the average shear stress in the oil?
80 Pa (b) 100 Pa (c) 125 Pa (d) 160 Pa
20. For the flow of oil (SG = 0.9, μ = 0.1 kg/m-s) through a long, straight , smooth 5-cm-diameter pipe at 14 m3/h, the pressure drop per meter is approximately:
2200 kPa (b) 2500 kPa (c) 2800 kPa (d) 10 MPa

7. MULTIPLE CHOICE QUESTIONS(Contd)
21. A fireboat pump delivers water to a 4-cm-diameter nozzle through a 12-cm-diameter pipe as shown here. If friction is neglected, and the flow rate is 500 gal/min, how high will this water jet rise?
(a) 2.0 m (b) 9.8 m (c) 32 m (d) 64 m
22. A smooth 12-cm-diameter sphere is immersed in a stream of 20 0C water (ρ = 998 kg/m3, μ = 1E-3 N-s/m2) moving at 6 m/s. The appropriate Reynolds number of this sphere is approximately:
2.5E5 (b) 7.2E5 (c) 2.5E6 (d) 7.2E6
23. A smooth 8-cm-diameter pipe 200 m long connects two reservoirs containing water at 20 0C. One of the reservoirs has a surface elevation of 700 m and the other a surface elevation of 560 m. If minor losses are neglected, the expected flow rate through the pipe is:
(a) m3/s (b) 2.87 m3/s (c) 134 m3/s (d) 172 m3/s

8. MULTIPLE CHOICE QUESTIONS(Contd)
24. For flow of sea-level standard (ν = 1.5E-5 m2/s) at 4 m/s, estimate the boundary layer thickness at x = 60 cm from the leading edge of a flat plate.
1.0 mm (b) 2.6 mm (c) 5.3 mm (d) 7.5 mm
25. A ship 150-m-long, designed to cruise at 18 kn, is to be tested in a tow tank with a model 3-m-long. The appropriate tow velocity is:
0.19 m/s (b m/s (c) 1.31 m/s (d) 2.55 m/s
26. A square wooden (SG = 0.6) rod, 5 cm by 5 cm by 10-m-long, floats vertically in water at 20 0C when 6 kg of steel (SG = 7.84) are attached to one end. How far above the water surface does the end of this rod protrude?
1.91 m (b) 2.34 m (c) 2.93 m (d) 3.62 m
27. Oil (μ = 0.1 kg/m-s, SG = 0.9) flows through a 5-m-long, straight, smooth 8-cm-diameter pipe. The maximum pressure drop for which laminar flow is expected is:
30 kPa (b) 40 kPa (c) 50 kPa (d) 60 kPa
28. Standard atmospheric air (ρ = 1.22 kg/m3) blows past a chimney 30-m-high and 80-cm-diameter. If the chimney may fracture at a base bending moment of 486 kN-m and the frontal area drag coefficient is 0.5, what is the maximum allowable wind velocity to avoid failure?
(a) 75 mi/h (b) 100 mi/h (c) 125 mi/h (d) 150 mi/h

9. MULTIPLE CHOICE QUESTIONS(Contd)
29. Water at 20 0C flows through a pipe at 300 gal/min ( L/s) with a friction head loss of 45 ft (13.76 m). What is the power required to drive this flow?
0.16 kW (b) 1.88 kW (c) 2.54 kW (d) 3.41 kW
30. Water is supplied to this 4-cm-diameter jet by a 7-cm-diameter pipe. The fluid in the manometer has a specific gravity of 1.6 and h = 66 cm. If the atmospheric pressure is 101 kPa, what is the average velocity in the jet? You may neglect friction.
2.4 m/s (b) 2.95 m/s (c) 4.55 m/s (d) 5.55 m/s