Q: A tank contains gasoline (specific gravity = 0.7) above water. If the vertical distance from the gasoline-water interface to the open top is 17 ft and the water layer is 3 ft deep, what is the pressure at the interface in psi? (Assume atmospheric pressure at the open top is 0 gauge.)

$$P = (0.7 \times 62.4 \text{ lb/ft}^3 \times 17 \text{ ft} + 62.4 \text{ lb/ft}^3 \times 3 \text{ ft}) / 144$$

Q: A U-tube manometer is connected to a tank containing compressed air. Mercury is used as the gage fluid. If the mercury column difference is $$h = 6$$ inches, what is the pressure difference in psi? (Specific gravity of mercury = 13.6, $$\gamma_{water} = 62.4 lb/ft$^3)$$

$$\Delta P = 13.6 \times 62.4 \text{ lb/ft}^3 \times 0.5 \text{ ft} / 144$$

Q: A rectangular concrete block (0.4 m x 0.4 m x 3 m, density = 300 kg/m$$^3) is $$fully immersed in seawater (density = 1025 kg/m$$^3). $$What is the tension in the cable holding the block underwater?

$$T = W_{block} - F_{buoyancy}$$, where $$W_{block} = 0.4 \times 0.4 \times 3 \times 300 \times 9.81$$ and $$F_{buoyancy} = 0.4 \times 0.4 \times 3 \times 1025 \times 9.81$$

Q: A slanted tube manometer is installed between two pipes. If the gage fluid has a specific gravity of 2.6 and the angle of inclination is $$30^ ext{o}$$, which equation gives the pressure difference between the pipes?

$$\Delta P = \$$gamma_2$$ l \sin \theta + \$$gamma_3$$ h_y - \$$gamma_1$$ h_y$$

Question 1

Which of the following best describes the difference between fluid statics and fluid dynamics?

Accepted Answer

Fluid statics deals with fluids in an equilibrium state of no shear stress, while fluid dynamics deals with portions of the fluid in motion.

Question 2

A tank contains gasoline (specific gravity = 0.7) above water. If the vertical distance from the gasoline-water interface to the open top is 17 ft and the water layer is 3 ft deep, what is the pressure at the interface in psi? (Assume atmospheric pressure at the open top is 0 gauge.)

Accepted Answer

$$P = (0.7 	imes 62.4 	ext{ lb/ft}^3 	imes 17 	ext{ ft} + 62.4 	ext{ lb/ft}^3 	imes 3 	ext{ ft}) / 144$$

Question 3

Which equation correctly expresses the pressure difference between two points in a column of incompressible fluid?

Accepted Answer

$$P_1$$ - $$P_2$$ = \gamma h$$

Question 4

A U-tube manometer is connected to a tank containing compressed air. Mercury is used as the gage fluid. If the mercury column difference is $$h = 6$$ inches, what is the pressure difference in psi? (Specific gravity of mercury = 13.6, $$\gamma_{water} = 62.4 lb/ft$^3)$$

Accepted Answer

$$\Delta P = 13.6 	imes 62.4 	ext{ lb/ft}^3 	imes 0.5 	ext{ ft} / 144$$

Question 5

Which of the following statements about the pressure at a point in a homogenous, incompressible fluid at rest is correct?

Accepted Answer

The pressure depends only on the depth below the fluid surface and the fluid's density.

Question 6

For a compressible fluid, which equation relates the pressure ratio between two points at different elevations?

Accepted Answer

$$\ln \frac{P_2$}{P_1$} = -\frac{gR}{T_o}(z_2$ - z_1$)$$

Question 7

A rectangular concrete block (0.4 m x 0.4 m x 3 m, density = 300 kg/m$$^3) is $$fully immersed in seawater (density = 1025 kg/m$$^3). $$What is the tension in the cable holding the block underwater?

Accepted Answer

$$T = W_{block} - F_{buoyancy}$$, where $$W_{block} = 0.4 	imes 0.4 	imes 3 	imes 300 	imes 9.81$$ and $$F_{buoyancy} = 0.4 	imes 0.4 	imes 3 	imes 1025 	imes 9.81$$

Question 8

Which property is used to compare the density of a fluid to that of water at a specified temperature?

Accepted Answer

Specific gravity

Question 9

In a differential U-tube manometer, which equation gives the pressure difference between two connected containers with different fluids?

Accepted Answer

$$\Delta P = \$$gamma_2$$ h_2$ + \$$gamma_3$$ h_3$ - \$$gamma_1$$ h_1$

Question 10

A body weighs 200 lb in air and 150 lb when submerged in water. What is its specific gravity?

Accepted Answer

$$SG = \frac{200}{200 - 150}$$

Question 11

Which of the following is true for an incompressible fluid?

Accepted Answer

Density is constant regardless of changes in pressure.

Question 12

What is the correct formula for the force exerted by a mass $$m$$ under gravity in the English system?

Accepted Answer

$$F = m \frac{g}{g_c}$$

Question 13

Which manometer type is best suited for measuring small gas pressure differences with high sensitivity?

Accepted Answer

Inclined tube manometer

Question 14

A slanted tube manometer is installed between two pipes. If the gage fluid has a specific gravity of 2.6 and the angle of inclination is $$30^	ext{o}$$, which equation gives the pressure difference between the pipes?

Accepted Answer

$$\Delta P = \$$gamma_2$$ l \sin 	heta + \$$gamma_3$$ h_y - \$$gamma_1$$ h_y$$

Question 15

Which principle explains why a floating object displaces a volume of fluid equal to its own weight?

Accepted Answer

Archimedes' Principle

Question 16

In the context of fluid mechanics, what does the term 'momentum transfer' refer to?

Accepted Answer

The change of velocity multiplied by mass flow rate

Question 17

Which of the following is NOT a property of fluids?

Accepted Answer

Elasticity

Question 18

If the pressure at the base of a skyscraper is $$P_1$$ and at the top is $$P_2$$, and air is treated as incompressible with density $$\rho$$, which equation gives the pressure ratio for a height difference $$h$$?

Accepted Answer

$$P_2$$ = $$P_1$$ - \rho g h$$

Question 19

Which of the following is a correct statement about the pressure at a point in a fluid?

Accepted Answer

Pressure at a point in a fluid is independent of direction.

Principles of Fluid Mechanics: Momentum Transfer Study Notes

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