Fluid Mechanics — Quiz 4

Questions in this quiz (11)

1. Oil is flowing through a pipe at a velocity of $$8\ \text{m/s}$$. Its kinematic viscosity is $$0.00025\ \text{m}^2/\text{s}$$. For a $$25\ \text{mm}$$ diameter pipe, the oil's Reynolds number is most nearly:

   • 800
   • 1000
   • 1200
   • 1500

2. A $$10\text{-in}$$ diameter pipe carries oil at a flow rate of $$2\ \text{mgd}$$. The oil's average velocity $$\left(\text{fps}\right)$$ in the pipe is most nearly:

   • 2
   • 6
   • 8
   • 16

3. Which of the following devices are used to measure flow in closed conduits?

   • Weir, Parshall flume, manometer
   • Venturimeter, orifice meter, pitot tube
   • Broad-crested weir, flume, nozzle
   • Pressure gage, weir, pitot tube

4. A turbine operates under a head of $$12\ \text{m}$$. Water flows through a $$0.12\ \text{m}$$ diameter exit pipe at a velocity of $$4\ \text{m/s}$$. Neglecting all losses, the turbine's output $$\left(\text{hp}\right)$$ is most nearly:

   • 0.8
   • 1.5
   • 3.2
   • 7.1

5. A small flat plate of surface area $$2\times10^{-3}\ \text{m}^2$$ is separated from a large plate by a fluid of $$0.2\ \text{cm}$$ thickness. A force of $$2\times10^{-2}\ \text{N}$$ is required to slide the small plate at a velocity of $$0.015\ \text{m/s}$$ with respect to the large plate. The viscosity $$\left(\text{N-s/m}^2\right)$$ of the fluid is most nearly:

   • $$1.3×10^{-3}$$
   • $$2.0×10^{-3}$$
   • $$3.5×10^{-3}$$
   • $$5.0×10^{-4}$$

6. A small flat plate of surface area $$8\times10^{-3}\ \text{m}^2$$ is placed on a fluid of $$3\times10^{-3}\ \text{m}$$ thickness. Most nearly how much horizontal force is required to slide the plate at $$0.08\ \text{m/s}$$ if the viscosity of the fluid is $$1.2\ \text{N-s/m}^2$$?

   • 0.19 N
   • 0.26 N
   • 0.31 N
   • 0.41 N

7. The viscosity of a fluid is $$800\times10^{-6}\ \text{N-s/m}^2$$. If the density of the fluid is $$950\ \text{kg/m}^3$$, the kinematic viscosity is most nearly:

   • $$0.84×10^{-6}$$ m²/s
   • $$0.50×10^{-6}$$ m²/s
   • $$0.95×10^{-6}$$ m²/s
   • $$0.72×10^{-6}$$ m²/s

8. What is the value of $$n$$ in the equation $$\tau=K\left(\frac{dv}{dy}\right)^n$$ for a dilatant (shear-thickening) fluid?

   • n = 0
   • n = 1
   • n > 1
   • n < 1

9. Which of the following statements is not true?

   • Buoyant force equals weight of displaced fluid
   • Floating body displaces fluid equal to its own weight
   • Center of buoyancy lies at centroid of displaced volume
   • Buoyant force depends only on fluid viscosity

10. An incompressible fluid flows through a $$5\text{-inch}$$ diameter pipe with a velocity of $$18\ \text{m/s}$$. If the pipe reduces to $$3\text{-inch}$$ diameter, the increase in velocity $$\left(\text{m/s}\right)$$ is most nearly:

    • 20.0
    • 32.0
    • 16.0
    • 12.5

11. Which of the following statements is true?

    • Hydraulic grade line excludes velocity head
    • Energy grade line includes velocity head
    • Bernoulli equation relates pressure, velocity and elevation head
    • All of the above