Fluid Mechanics — Quiz 6

Questions in this quiz (10)

1. A barometer contains oil with a density of $$850\ \text{kg/m}^3$$. Atmospheric conditions are $$92\ \text{kPa}$$ and $$25^\circ\text{C}$$. The vapor pressure of the oil is $$0.002\ \text{kPa}$$. The column of oil will rise to a height of most nearly:

   • 8.5 m
   • 10.8 m
   • 11.0 m
   • 12.3 m

2. A pitot tube is used to measure the flow of an incompressible fluid with a density of $$920\ \text{kg/m}^3$$. The velocity is measured as $$3\ \text{m/s}$$, and the stagnation pressure is $$18.5\ \text{kPa}$$. The static pressure of the fluid where the measurement is taken is most nearly:

   • 14.4 kPa
   • 15.1 kPa
   • 16.2 kPa
   • 17.0 kPa

3. A $$1\!:\!1$$ model of a submarine is tested in a wind tunnel according to Reynolds number similarity. At the testing temperature, the kinematic viscosity of air is $$1.50\times10^{-5}\ \text{m}^2/\text{s}$$, and the kinematic viscosity of water is $$1.20\times10^{-6}\ \text{m}^2/\text{s}$$. If the velocity of the submarine in water is $$6\ \text{m/s}$$, the air velocity in the wind tunnel should be most nearly:

   • 50 m/s
   • 60 m/s
   • 75 m/s
   • 90 m/s

4. A $$2.5\ \text{m}$$ tall tank with $$0.6\ \text{m}$$ inside diameter is filled with water. A $$12\ \text{mm}$$ hole is opened $$1.0\ \text{m}$$ from the bottom of the tank. Ignoring orifice losses, the velocity of exiting water is most nearly:

   • 5.0 m/s
   • 5.4 m/s
   • 5.9 m/s
   • 6.3 m/s

5. A centrifugal pump operates at $$1800\ rpm$$ and delivers $$0.12\ m^3/s$$ against a head of $$30\ m$$ while consuming $$40\ kW$$. If the pump speed is increased to $$2400\ rpm$$, determine the new power requirement using pump affinity laws.

   • 63.2 kW
   • 71.1 kW
   • 75.8 kW
   • 94.8 kW

6. A semicircular gate with a radius of $$1.2\ m$$ and width of $$2.5\ m$$ is submerged with its flat side horizontal and curved surface facing upward. Water fills the region above the curved surface. Assuming $$\rho=1000\ kg/m^3$$ and $$g=9.81\ m/s^2$$, determine the vertical component of the hydrostatic force on the curved surface.

   • 52.6 kN
   • 68.4 kN
   • 73.2 kN
   • 91.5 kN

7. Water flows at $$15\ m^3/s$$ in a rectangular open channel that is $$5\ m$$ wide. Assuming $$g=9.81\ m/s^2$$, determine the critical depth.

   • 0.92 m
   • 1.08 m
   • 1.22 m
   • 1.35 m

8. A hydraulic turbine operates under a net head of $$60\ m$$ with a flow rate of $$4\ m^3/s$$. The turbine produces a shaft power of $$1800\ kW$$. Assuming $$\rho=1000\ kg/m^3$$ and $$g=9.81\ m/s^2$$, determine the efficiency of the turbine.

   • 76%
   • 82%
   • 89%
   • 94%

9. A water jet with a velocity of $$20\ m/s$$ and cross-sectional area of $$0.0025\ m^2$$ strikes a flat plate moving at $$8\ m/s$$ in the same direction as the jet. Assuming $$\rho=1000\ kg/m^3$$, determine the force exerted on the plate.

   • 0.96 kN
   • 1.20 kN
   • 1.44 kN
   • 1.88 kN

10. Water flows through a horizontal Venturi meter with an inlet diameter of $$250\ mm$$ and throat diameter of $$125\ mm$$. The inlet pressure is $$180\ kPa$$ and inlet velocity is $$2.5\ m/s$$. Assuming $$\rho=1000\ kg/m^3$$, determine the pressure at the throat.

    • 120 kPa
    • 135 kPa
    • 150 kPa
    • 165 kPa