Civil Engineering PE Hydraulics and Open-Channel Flow 3

Question 1

A spillway has discharge coefficient Cd = 0.85, head H = 1.5 m, and length L = 10 m. The discharge over the spillway is most nearly:

Accepted Answer

66 m³/s

Answer

83 m³/s

Answer

99 m³/s

Answer

116 m³/s

Question 2

In gradually varied flow (GVF), an M2 profile occurs when:

Accepted Answer

Flow is subcritical and depth decreases toward critical depth downstream

Answer

Flow is supercritical and depth increases downstream

Answer

Flow is subcritical and depth increases toward normal depth downstream

Answer

Flow is supercritical and depth decreases toward normal depth upstream

Question 3

The energy loss in a hydraulic jump in a rectangular channel is given by:

Accepted Answer

ΔE = (y₂ − y₁)³ / (4y₁y₂)

Answer

ΔE = (y₂ − y₁)²

Answer

ΔE = (y₂ − y₁)³ / (2y₁y₂)

Answer

ΔE = V₁²/(2g) − V₂²/(2g)

Question 4

A pipe transitions from 300 mm diameter to 600 mm diameter. If velocity in the smaller pipe is 3 m/s, the velocity in the larger pipe is:

Accepted Answer

0.75 m/s

Answer

0.25 m/s

Answer

1.50 m/s

Answer

6.00 m/s

Question 5

For a trapezoidal channel, the most hydraulically efficient section has which property?

Accepted Answer

Hydraulic radius equals half the water depth

Answer

Bottom width equals water depth

Answer

Side slopes are vertical (z = 0)

Answer

Top width equals twice the bottom width

Question 6

A suppressed rectangular weir (no end contractions) has L = 3 m, H = 0.5 m, and Cd = 0.61. Discharge is most nearly:

Accepted Answer

1.91 m³/s

Answer

0.96 m³/s

Answer

1.22 m³/s

Answer

1.55 m³/s

Question 7

Specific energy in an open channel is measured relative to the:

Accepted Answer

Channel invert (bottom)

Answer

Datum at mean sea level

Answer

Water surface elevation

Answer

Energy grade line