FLUID MECHANICS MCQ SET 1
Q1. Which branch of science deals with the study of fluids at rest or in motion?
A) Thermodynamics
B) Fluid Mechanics
C) Heat Transfer
D) Solid Mechanics
Answer: B) Fluid Mechanics
Explanation: Fluid Mechanics studies the behavior of fluids (liquids and gases) whether stationary or in motion.
Q2. The density of water at 4ยฐC is approximately:
A) 1000 kg/mยณ
B) 1020 kg/mยณ
C) 998 kg/mยณ
D) 950 kg/mยณ
Answer: A) 1000 kg/mยณ
Explanation: At 4ยฐC, water reaches its maximum density, approximately 1000 kg/mยณ.
Q3. Which of the following is a dimensionless quantity?
A) Velocity
B) Pressure
C) Reynolds Number
D) Viscosity
Answer: C) Reynolds Number
Explanation: Reynolds number is a ratio of inertial to viscous forces and has no physical dimensions.
Q4. The unit of dynamic viscosity in SI system is:
A) Nยทs/mยฒ
B) Paยทs
C) Both A and B
D) N/mยฒ
Answer: C) Both A and B
Explanation: 1 Pascal-second (Paยทs) = 1 Nยทs/mยฒ; both represent dynamic viscosity in SI units.
Q5. Which of the following fluids is incompressible?
A) Air
B) Steam
C) Water
D) Gasoline
Answer: C) Water
Explanation: Liquids like water are treated as incompressible since their volume change with pressure is negligible.
Q6. Continuity equation is based on the law of:
A) Conservation of Mass
B) Conservation of Momentum
C) Conservation of Energy
D) Thermodynamics
Answer: A) Conservation of Mass
Explanation: The continuity equation states that mass entering a control volume equals the mass leaving it.
Q7. Bernoulliโs equation applies to:
A) Viscous flow
B) Steady, incompressible, inviscid flow
C) Compressible flow
D) Turbulent flow
Answer: B) Steady, incompressible, inviscid flow
Explanation: Bernoulliโs theorem is valid only for steady and frictionless flow along a streamline.
Q8. The SI unit of pressure is:
A) Pascal
B) Bar
C) Newton
D) Joule
Answer: A) Pascal
Explanation: Pressure = Force/Area; 1 Pascal = 1 N/mยฒ.
Q9. The viscosity of a liquid generally:
A) Increases with temperature
B) Decreases with temperature
C) Remains constant
D) Becomes zero
Answer: B) Decreases with temperature
Explanation: As temperature increases, intermolecular forces reduce, decreasing viscosity.
Q10. The viscosity of gases:
A) Decreases with temperature
B) Increases with temperature
C) Remains constant
D) Is independent of temperature
Answer: B) Increases with temperature
Explanation: Higher temperature causes faster molecular motion, increasing gas viscosity.
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