hydrology exam 2

Which of the following is/are considered a fluid?

A. Solid

B. Liquid

C. Gas

B. Liquid and C. Gas

The unite pressure in SI is what?

Pascal (Pa)

In a static liquid, pressure at the same depth is . . .

Equal in all directions

The pressure at the bottom of two tanks with equal depth but different shapes is . . .

Equal in both tanks

The total pressure in a fluid is the sum of what?

Atmospheric pressure and gauge pressure

What is the approximate atmospheric pressure at sea level?

101.3 kPa

Gauge pressure is defined as:

Absolute pressure - atmospheric pressure

A U-tube manometer is used to measure

Pressure

Viscosity is defined as the ration of . . .

Shear stress to velocity gradient

What decreases with increasing temperature?

Viscosity of water

The Bernoulli equation is based on what?

Conservation of energy

In Bernoulli’s principle, slower-moving fluids create what kind of pressure?

Greater pressure

In the fire hose example, why is the nozzle velocity higher than at the base?

Cross-sectional area is smaller

• the area the water is traveling gets smaller at the nozzle

For laminar flow, Reynolds number (Re) is:

< 2000

For turbulent flow, Reynolds number (Re) is:

>4000

In fluid mechanics, “head loss” refers to:

Loss of energy due to friction

Head loss in pipe flow is directly proportionate to . . .

• Flow velocity squared

• Pipe length

• Friction factor

Specific gravity

Ratio of density of a substance to density of water

Specific weight

Weight per unit volume of a material

What is the amount of pressure exerted by water at a depth of 1m?

(1.0 × 10³ kg/m³)(9.8 m/s²)

What is the conversion of kPa to PA?

1 kPa =1,000 Pa

How many psi does atmospheric pressure equal?

101.3 kPa =14.7 psi

What is the meaning of this equation μ=d • τ / υ plate

Viscosity = distance • shear stress / velocity of plate

Absolute pressure

= gauge pressure + atmospheric pressure

What is atmospheric pressure?

101.3 kPa

What is gauge pressure at the waters surface?

Zero

Body forces

Forces that do not require direct contact

• Gravity

• Electromagnetic force

Surface forces

Caused by direct contact between two fluid particles or between fluid and solid

What is the definition of the hydrostatic equation?

Variation of pressure with depth in a fluid at rest

What is the viscosity of water at 20 º?

1.0 × 10-³ Pa•s

What is the density of water?

1000 kg m -³

What are the two types of stress?

Normal stress → pressure

Tangential stress → shear stress