Civil Engineering Online Review

Theoretical velocity generated by a 3 m hydraulic head is:

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At or below critical velocity in a small pipe or at very low velocities, the loss of head due to friction

a)  varies directly as the velocity

b)  is infinitely large

c)  equals the velocity head

d)  can be ignored

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A 20cm diameter pipe of length 100m with z = 60m with f = 0.02 and loss of head due to entrance coefficient k = 0.5. What is the flow rate?

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The head loss in 50m of 12cm diameter pipe is known to be 6m when liquid specific gravity = 0.9 of viscosity 0.04 N-s/m flows at 0.06 m/s. Find the shear stress at the wall of the pipe?

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The head loss in 50m of 12cm diameter pipe is known to be 6m when liquid specific gravity = 0.9 of viscosity 0.04 N-s/m flows at 0.06 m/s. Find the shear stress at the wall of the pipe?

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What are the principal impurities found in water?

a)  nonionic and undissolved

b)  all of these

c)  gasses

d)  ionic and dissolved

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What is the measurement of the amount of oxygen required to stabilize the waste completely.

a)  chemical oxygen demand

b)  biological oxygen demand

c)  theoretical oxygen demand

d)  none of these

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Find the width in m of the channel at the back of a suppressed weir using the following data: H = 28.5cm; d = 2.485m; Q = 0.84 cu.m/sec. Consider the velocity of approach and use the Francis formula.

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Name method(s) of measuring stream flow.

a)  open channel formulas

b)  weir formulas

c)  price current meter and weir formulas

d)  all of the above

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The bottom width of a trapezoidal canal is 2.5m. and its sides are both inclined at 60° with the horizontal. Water flows at a depth of 3m. Find the discharge in cu.m/sec. if s = 0.0008 and n = 0.03. Use the Chezy formula.

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A spillway controls reservoir 4.6 hectares in area. The permanent crest is at elevation 75m. Water can be drawn from elevation 76.5m to elev.75.5m. in 42 minutes. Find the length of the spillway in m. Use the Francis formula.

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The bottom width of a canal is 4m. and the side slopes are 2 horizontal to 1.0 vertical. Find the hydraulic radius, in m. when water flows 1.25 m. deep.

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Which method has the best control of water supplied?

a)  furrow

b)  flooding

c)  subirrigation

d)  trickle irrigation

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This formula applies to steady flow in open channels, and is in the from

Where:

V = velocity

C = an empirical coefficient

R = hydraulic radius

S = slope of the hydraulic gradient

a)  Darcy-Weisbach formula

b)  Manning formula

c)  Chezy formula

d)  Hazen-Williams formula

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Water flows in a 2m. wide rectangular flume at the rate of 2.75 cu.m./sec. with a  mean velocity of 3.5 m/s. To what depth, in cm., can the water jump? Use g = 0.91.

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What is the graph that plots the measured stream flow discharge vs. water surface elevation?

a)  infiltration curve

b)  all of these

c)  rating curve

d)  hydrograph

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A rectangular concrete flume, 4m wide, carries water at the rate 5 cu.m/sec. Determine the critical depth in m. Use g = 9.81.

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The side slope of a trapezoidal open channel are 1.0 horizontal to 1.732 vertical. The bottom width is 2.5m and the depth of flow is 3m. n = 0.015 and s = 0.0004. Find the velocity of flow in m/s using the manning formula.

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The length of the crest of a trapezoidal weir is 2m. The sides are slopping at 75°57’49” with the horizontal. Find the discharge in cu.m/sec if the head on the weir is 0.5m.

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Water can jump from a depth of 30 cm. to 75 cm. in a rectangular flume. Determine the discharge in cu.m/sec. if the flume is 2.75m. wide. Use g = 9.81.

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What is the rate of flow of water passing through a pipe with a diameter of 20 mm and speed of 0.5 m/sec?

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The discharge over a trapezoidal weir is 1.315 cu.m/sec. The crest’s length is 2m and the sides are slanting at 75°57’49” with the horizontal. Find the head on the weir in m.

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Consider an arbitrary shaped body with a submerged volume Vs and density rs, submerged in a fluid of density rf. What is the effective weight of the body in the fluid? Use g as the density of water.

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This is a measure of the relative importance of inertial forces to viscous forces. At sufficiently high values, flow become turbulent.

a)  Weber Number

b)  Froide Number

c)  Moody Number

d)  Reynolds Number

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The fundamental reference dimensions are mass, length and time. The fundamental Si units for them are kilogram (kg), meter (m), and seconds (s), respectively. The unit of force derived from these units in the Newton (N). Consequently, the unit pressure N/m² is called:

a)  Stress

b)  Pascal

c)  Gage

d)  MegaPascal

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A trapezoidal flume of most efficient proportion has a base width of 1.5m. Its full discharge is 3cu.m/sec. If the same material were used for the most efficient rectangular section, by how much would the discharge decrease in cu.m/sec.

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The relative roughness of a pipe is dependent on

a)  length

b)  absolute roughness of the interior surface and diameter

c)  diameter

d)  absolute roughness of the interior surface

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Absolute viscosity of a fluid varies with pressure and temperature and is defined as a function of:

a)  density and angular deformation rate

b)  density and shear stress

c)  shear stress and density

d)  shear stress and angular deformation rate
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A constant radius arch dam has a vertical upstream face. The radius of the arch is R and the height of the dam (also the height of the water) is H. The arch subtends an angle of 2Ø. What is the net vertical force acting on the dam face due to hydrostatic forces? Use g as the density of the water.

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What is the term for capillary water in the smaller pore surfaces on the soil?

a)  interception

b)  depression storage

c)  soil moisture

d)  basin recharge

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