Fluid Flow

Question 1

1. The branch of fluid mechanics dealing with fluids in motion is called ___.
   A. Hydrostatics B. Hydrodynamics C. Kinematics D. Fluid Resistance

Answer 1

✅ Answer: B – Hydrodynamics
Study of fluids under motion considering forces.

Question 2

2. The law of conservation of mass for a steady incompressible flow is expressed by ___.
   A. Bernoulli’s Equation B. Pascal’s Law C. Continuity Equation D. Darcy’s Law

Answer 2

✅ Answer: C – Continuity Equation
A₁V₁ = A₂V₂ → flow rate constant.

Question 3

3. In the continuity equation, A₁V₁ = A₂V₂, when area decreases, velocity ___.
   A. Decreases B. Increases C. Remains constant D. Becomes zero

Answer 3

✅ Answer: B – Increases
Inverse relationship between velocity and area.

Question 4

4. The total energy per unit weight of a fluid in motion is given by ___.
   A. γh B. Bernoulli’s Equation C. P/ρ + V²/2g + z D. ρgh

Answer 4

✅ Answer: C – P/ρ + V²/2g + z
Sum of pressure, velocity, and potential heads.

Question 5

5. Bernoulli’s equation is derived from ___.
   A. Newton’s 1st Law B. Law of Conservation of Energy C. Pascal’s Law D. Continuity Equation

Answer 5

✅ Answer: B – Law of Conservation of Energy
Energy remains constant along streamline.

Question 6

6. Bernoulli’s equation neglects ___.
   A. Gravity B. Friction losses C. Velocity D. Pressure

Answer 6

✅ Answer: B – Friction losses
Applies to ideal (non-viscous) fluids.

Question 7

7. The head loss due to friction in a pipe is calculated using ___.
   A. Bernoulli’s B. Darcy–Weisbach C. Pascal’s D. Manning’s

Answer 7

✅ Answer: B – Darcy–Weisbach Equation
h_f = f (L/D) (V²/2g).

Question 8

8. In the Darcy–Weisbach formula, the friction factor f depends on ___.
   A. Pipe length only B. Roughness & Reynolds number C. Fluid color D. Flow direction

Answer 8

✅ Answer: B – Roughness & Reynolds number
Determines laminar or turbulent flow.

Question 9

9. For laminar flow in a circular pipe, the friction factor is ___.
   A. 64/Re B. 16/Re C. 0.316/Re D. 0.079/Re⁰·²⁵

Answer 9

✅ Answer: A – 64/Re
Valid for Re < 2000.

Question 10

10. Flow with Reynolds number less than 2000 is called ___.
    A. Laminar B. Transitional C. Turbulent D. Supersonic

Answer 10

✅ Answer: A – Laminar
Streamlines smooth and orderly.

Question 11

11. Turbulent flow occurs when Reynolds number is ___.
    A. < 2000 B. 2000–4000 C. > 4000 D. Constant

Answer 11

✅ Answer: C – > 4000
Irregular mixing and eddies occur.

Question 12

12. The unit of discharge (flow rate) in SI system is ___.
    A. m³ B. m³/s C. m/s D. m²/s

Answer 12

✅ Answer: B – m³/s
Volume of fluid passing per second.

Question 13

13. The head loss due to sudden enlargement is ___.
    A. (V₂ – V₁)²/2g B. (V₁ – V₂)²/2g C. (V₂/V₁)² D. (V₂ + V₁)²

Answer 13

✅ Answer: B – (V₁ – V₂)² / 2g
Loss from expansion turbulence.

Question 14

14. The velocity distribution in laminar flow through a pipe is ___.
    A. Uniform B. Parabolic C. Linear D. Random

Answer 14

✅ Answer: B – Parabolic
Maximum at center, zero at wall.

Question 15

15. The ratio of actual discharge to theoretical discharge is called ___.
    A. Coefficient of Contraction B. Coefficient of Velocity C. Coefficient of Discharge D. Flow Ratio

Answer 15

✅ Answer: C – Coefficient of Discharge
C_d = Q_actual / Q_theoretical.

Question 16

16. Flow through a small orifice is analyzed using ___.
    A. Continuity only B. Bernoulli’s Equation C. Both A & B D. Pascal’s Law

Answer 16

✅ Answer: C – Both A & B
Combines energy and continuity relations.

Question 17

17. The theoretical velocity of jet through orifice = ___.
    A. √(2gH) B. gH C. 2gH D. H/2g

Answer 17

✅ Answer: A – √(2gH)
From Bernoulli: V = √(2gh).

Question 18

18. The flow through a long pipe consists of ___.
    A. Entrance loss B. Friction loss C. Exit loss D. All of the above

Answer 18

✅ Answer: D – All of the above
Total head loss = sum of major + minor losses.

Question 19

19. When two or more pipes are connected in series, total head loss = ___.
    A. Same in each pipe B. Sum of individual losses C. Product of losses D. Zero

Answer 19

✅ Answer: B – Sum of individual losses
h_f(total) = h_f₁ + h_f₂ + …

Question 20

20. For pipes in parallel, total discharge = ___.
    A. Sum of individual discharges B. Average of discharges C. Equal in each pipe D. Minimum of all

Answer 20

✅ Answer: A – Sum of individual discharges
Q_total = Q₁ + Q₂ + Q₃.

Question 21

21. Continuity equation for compressible flow is ___.
    A. A₁V₁ = A₂V₂ B. ρ₁A₁V₁ = ρ₂A₂V₂ C. P₁V₁ = P₂V₂ D. A/V = constant

Answer 21

✅ Answer: B – ρ₁A₁V₁ = ρ₂A₂V₂
Accounts for variable density.

Question 22

22. In open channel flow, the ratio of inertial to gravitational forces is expressed by ___.
    A. Reynolds Number B. Froude Number C. Weber Number D. Mach Number

Answer 22

✅ Answer: B – Froude Number
Fr = V / √(gD).

Question 23

23. The condition of flow when Froude Number = 1 is called ___.
    A. Subcritical B. Supercritical C. Critical D. Turbulent

Answer 23

✅ Answer: C – Critical
Separates tranquil and rapid flow.

Question 24

24. The discharge through a venturimeter is proportional to ___.
    A. √h B. h C. h² D. 1/h

Answer 24

✅ Answer: A – √h
From Bernoulli and continuity combined.

Question 25

25. In a Pitot tube, velocity of flow is proportional to ___. A. √(2gh) B. h² C. 2gh D. 1/h

Answer 25

✅ Answer: A – √(2gh) Velocity head measured by pressure difference.