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FE Civil Hydraulics & Hydrology Practice
Questions 2026–2027 | Complete Exam
Prep with Answers & Detailed
Explanations
1. A water reservoir discharges through a 150-mm-diameter pipe. The velocity
in the pipe is 3.2 m/s. What is the volumetric flow rate?
A. 0.028 m³/s
B. 0.057 m³/s
C. 0.113 m³/s
D. 0.226 m³/s
Answer: 0.057 m³/s
Rationale: The discharge is Q = AV. The pipe area is A = π(0.15²)/4 = 0.01767 m².
Therefore, Q = 0.01767(3.2) ≈ 0.0565 m³/s, or approximately 0.057 m³/s.
, 2. Water flows through a horizontal pipe that contracts from 300 mm to 150
mm in diameter. If the upstream velocity is 2.0 m/s and losses are
negligible, what is the downstream velocity?
A. 0.5 m/s
B. 1.0 m/s
C. 4.0 m/s
D. 8.0 m/s
Answer: 8.0 m/s
Rationale: Continuity requires A₁V₁ = A₂V₂. Because area varies with diameter
squared, A₁/A₂ = (0.30/0.15)² = 4. Thus V₂ = 4(2.0) = 8.0 m/s.
3. A pipe carries water at 20°C with velocity 1.5 m/s. Its diameter is 100 mm.
Using a kinematic viscosity of 1.0 × 10⁻⁶ m²/s, what is the Reynolds
number?
A. 1,500
B. 15,000
C. 150,000
D. 1,500,000
Answer: 150,000
Rationale: Reynolds number is Re = VD/ν = (1.5)(0.10)/(1.0 × 10⁻⁶) = 150,000.
The flow is therefore turbulent.
4. A pressure tap in a water pipe indicates a gauge pressure of 250 kPa. What
is the corresponding pressure head?
A. 2.55 m
B. 25.5 m
,C. 255 m
D. 2,550 m
Answer: 25.5 m
Rationale: Pressure head is p/γ. For water, γ ≈ 9.81 kN/m³. Thus hₚ = 250/9.81 ≈
25.5 m of water.
5. Water flows through a pipe at 4 m/s. If the velocity head is required, what
value should be used?
A. 0.41 m
B. 0.82 m
C. 1.63 m
D. 8.16 m
Answer: 0.82 m
Rationale: Velocity head is V²/(2g). Therefore, hᵥ = 4²/(2 × 9.81) = 0.815 m,
approximately 0.82 m.
6. A hydraulic system has an upstream pressure head of 30 m, velocity head
of 2 m, and elevation head of 15 m. At another section, the pressure head
is 18 m, velocity head is 4 m, and elevation head is 20 m. Neglecting losses,
what is the energy-head difference?
A. 1 m
B. 5 m
C. 9 m
D. 15 m
Answer: The specified conditions are inconsistent with negligible losses.
, Rationale: Bernoulli's equation requires 30 + 2 + 15 = 47 m upstream and 18 + 4
+ 20 = 42 m downstream. The 5-m difference represents an energy loss, so the
two sections cannot satisfy Bernoulli's equation with zero loss.
7. A pipeline has a Darcy friction factor of 0.025, length of 800 m, diameter of
0.40 m, and velocity of 2.5 m/s. What is the major head loss?
A. 2.03 m
B. 4.97 m
C. 6.37 m
D. 10.2 m
Answer: 6.37 m
Rationale: Darcy-Weisbach gives h_f = f(L/D)(V²/2g). Substitution gives
0.025(800/0.40)(2.5²/(2 × 9.81)) ≈ 6.37 m.
8. A minor loss coefficient for a valve is K = 4.0. If water flows through the
valve at 3 m/s, what is the head loss?
A. 0.46 m
B. 0.92 m
C. 1.84 m
D. 3.67 m
Answer: 1.84 m
Rationale: Minor loss is h_L = K(V²/2g). Thus h_L = 4(9/(19.62)) ≈ 1.84 m.
9. Which parameter most directly represents the ratio of inertial forces to
viscous forces in pipe flow?
FE Civil Hydraulics & Hydrology Practice
Questions 2026–2027 | Complete Exam
Prep with Answers & Detailed
Explanations
1. A water reservoir discharges through a 150-mm-diameter pipe. The velocity
in the pipe is 3.2 m/s. What is the volumetric flow rate?
A. 0.028 m³/s
B. 0.057 m³/s
C. 0.113 m³/s
D. 0.226 m³/s
Answer: 0.057 m³/s
Rationale: The discharge is Q = AV. The pipe area is A = π(0.15²)/4 = 0.01767 m².
Therefore, Q = 0.01767(3.2) ≈ 0.0565 m³/s, or approximately 0.057 m³/s.
, 2. Water flows through a horizontal pipe that contracts from 300 mm to 150
mm in diameter. If the upstream velocity is 2.0 m/s and losses are
negligible, what is the downstream velocity?
A. 0.5 m/s
B. 1.0 m/s
C. 4.0 m/s
D. 8.0 m/s
Answer: 8.0 m/s
Rationale: Continuity requires A₁V₁ = A₂V₂. Because area varies with diameter
squared, A₁/A₂ = (0.30/0.15)² = 4. Thus V₂ = 4(2.0) = 8.0 m/s.
3. A pipe carries water at 20°C with velocity 1.5 m/s. Its diameter is 100 mm.
Using a kinematic viscosity of 1.0 × 10⁻⁶ m²/s, what is the Reynolds
number?
A. 1,500
B. 15,000
C. 150,000
D. 1,500,000
Answer: 150,000
Rationale: Reynolds number is Re = VD/ν = (1.5)(0.10)/(1.0 × 10⁻⁶) = 150,000.
The flow is therefore turbulent.
4. A pressure tap in a water pipe indicates a gauge pressure of 250 kPa. What
is the corresponding pressure head?
A. 2.55 m
B. 25.5 m
,C. 255 m
D. 2,550 m
Answer: 25.5 m
Rationale: Pressure head is p/γ. For water, γ ≈ 9.81 kN/m³. Thus hₚ = 250/9.81 ≈
25.5 m of water.
5. Water flows through a pipe at 4 m/s. If the velocity head is required, what
value should be used?
A. 0.41 m
B. 0.82 m
C. 1.63 m
D. 8.16 m
Answer: 0.82 m
Rationale: Velocity head is V²/(2g). Therefore, hᵥ = 4²/(2 × 9.81) = 0.815 m,
approximately 0.82 m.
6. A hydraulic system has an upstream pressure head of 30 m, velocity head
of 2 m, and elevation head of 15 m. At another section, the pressure head
is 18 m, velocity head is 4 m, and elevation head is 20 m. Neglecting losses,
what is the energy-head difference?
A. 1 m
B. 5 m
C. 9 m
D. 15 m
Answer: The specified conditions are inconsistent with negligible losses.
, Rationale: Bernoulli's equation requires 30 + 2 + 15 = 47 m upstream and 18 + 4
+ 20 = 42 m downstream. The 5-m difference represents an energy loss, so the
two sections cannot satisfy Bernoulli's equation with zero loss.
7. A pipeline has a Darcy friction factor of 0.025, length of 800 m, diameter of
0.40 m, and velocity of 2.5 m/s. What is the major head loss?
A. 2.03 m
B. 4.97 m
C. 6.37 m
D. 10.2 m
Answer: 6.37 m
Rationale: Darcy-Weisbach gives h_f = f(L/D)(V²/2g). Substitution gives
0.025(800/0.40)(2.5²/(2 × 9.81)) ≈ 6.37 m.
8. A minor loss coefficient for a valve is K = 4.0. If water flows through the
valve at 3 m/s, what is the head loss?
A. 0.46 m
B. 0.92 m
C. 1.84 m
D. 3.67 m
Answer: 1.84 m
Rationale: Minor loss is h_L = K(V²/2g). Thus h_L = 4(9/(19.62)) ≈ 1.84 m.
9. Which parameter most directly represents the ratio of inertial forces to
viscous forces in pipe flow?
