FLUID MECHANICS FUNDAMENTALS
AND APPLICATIONS COMPREHENSIVE
QUESTIONS AND ANSWERS
1. Under the continuum hypothesis, which of the following is true?
A. Fluid properties are calculated by summing the behavior of individual molecules.
B. The mean free path of molecules is large compared to the characteristic length of the
system.
C. The Knudsen number is typically much greater than 1.
D. Fluid properties vary continuously in space and are treated as point functions.
Answer: D
Conceptual Explanation: The continuum hypothesis treats fluids as continuous matter
where properties are defined at every point, which is valid when the characteristic length is
much larger than the mean free path.
2. Which property describes the rate at which momentum is transferred between fluid
layers?
A. Surface Tension
,B. Dynamic Viscosity
C. Bulk Modulus
D. Kinematic Viscosity
Answer: B
Conceptual Explanation: Dynamic viscosity is a measure of the internal resistance to flow
and represents the ratio of shear stress to the rate of shear strain.
3. In a Newtonian fluid, the relationship between shear stress and the rate of deformation is:
A. Exponential
B. Logarithmic
C. Inverse
D. Linear
Answer: D
Conceptual Explanation: For Newtonian fluids, shear stress is directly proportional to the
velocity gradient perpendicular to the direction of flow.
4. What happens to the viscosity of a liquid and a gas as temperature increases?
A. Liquid viscosity increases, gas viscosity decreases.
B. Both increase.
C. Liquid viscosity decreases, gas viscosity increases.
, D. Both decrease.
Answer: C
Conceptual Explanation: In liquids, increased temperature reduces intermolecular forces,
lowering viscosity. In gases, it increases molecular collisions, raising viscosity.
5. The pressure at a point in a fluid at rest:
A. Is greater in the downward direction due to gravity.
B. Depends on the surface area of the container.
C. Is the same in all directions.
D. Is zero if the fluid is incompressible.
Answer: C
Conceptual Explanation: According to Pascal’s law, pressure at a point in a static fluid is
independent of direction.
6. A hydrometer is used to measure the specific gravity of a liquid. It works based on:
A. Bernoulli’s Principle
B. Archimedes’ Principle
C. Newton’s Second Law
D. Pascal’s Law
Answer: B
AND APPLICATIONS COMPREHENSIVE
QUESTIONS AND ANSWERS
1. Under the continuum hypothesis, which of the following is true?
A. Fluid properties are calculated by summing the behavior of individual molecules.
B. The mean free path of molecules is large compared to the characteristic length of the
system.
C. The Knudsen number is typically much greater than 1.
D. Fluid properties vary continuously in space and are treated as point functions.
Answer: D
Conceptual Explanation: The continuum hypothesis treats fluids as continuous matter
where properties are defined at every point, which is valid when the characteristic length is
much larger than the mean free path.
2. Which property describes the rate at which momentum is transferred between fluid
layers?
A. Surface Tension
,B. Dynamic Viscosity
C. Bulk Modulus
D. Kinematic Viscosity
Answer: B
Conceptual Explanation: Dynamic viscosity is a measure of the internal resistance to flow
and represents the ratio of shear stress to the rate of shear strain.
3. In a Newtonian fluid, the relationship between shear stress and the rate of deformation is:
A. Exponential
B. Logarithmic
C. Inverse
D. Linear
Answer: D
Conceptual Explanation: For Newtonian fluids, shear stress is directly proportional to the
velocity gradient perpendicular to the direction of flow.
4. What happens to the viscosity of a liquid and a gas as temperature increases?
A. Liquid viscosity increases, gas viscosity decreases.
B. Both increase.
C. Liquid viscosity decreases, gas viscosity increases.
, D. Both decrease.
Answer: C
Conceptual Explanation: In liquids, increased temperature reduces intermolecular forces,
lowering viscosity. In gases, it increases molecular collisions, raising viscosity.
5. The pressure at a point in a fluid at rest:
A. Is greater in the downward direction due to gravity.
B. Depends on the surface area of the container.
C. Is the same in all directions.
D. Is zero if the fluid is incompressible.
Answer: C
Conceptual Explanation: According to Pascal’s law, pressure at a point in a static fluid is
independent of direction.
6. A hydrometer is used to measure the specific gravity of a liquid. It works based on:
A. Bernoulli’s Principle
B. Archimedes’ Principle
C. Newton’s Second Law
D. Pascal’s Law
Answer: B
