FLUID MECHANICS FUNDAMENTALS
AND APPLICATIONS (CENGEL) -
COMPREHENSIVE EXAM QUESTIONS
AND ANSWERS
1. According to the no-slip condition, what is the velocity of a fluid in direct contact with a
solid surface?
A. Equal to the bulk velocity of the fluid
B. Dependent only on the fluid’s density
C. Infinite due to molecular friction
D. Zero relative to the solid surface
Answer: D
Conceptual Explanation: The no-slip condition states that a fluid in motion comes to a
complete stop at the surface and assumes the zero velocity of the surface.
2. Which dimensionless number represents the ratio of inertial forces to viscous forces?
A. Froude Number
B. Mach Number
,C. Weber Number
D. Reynolds Number
Answer: D
Conceptual Explanation: The Reynolds number (Re = rhoVL/mu) characterizes the flow
regime by comparing inertia to viscosity.
3. In a Newtonian fluid, the shear stress is linearly proportional to:
A. The pressure gradient
B. The velocity gradient perpendicular to the flow
C. The square of the velocity
D. The fluid density
Answer: B
Conceptual Explanation: For Newtonian fluids, shear stress is proportional to the strain
rate (velocity gradient) through the dynamic viscosity.
4. Vapor pressure is defined as the pressure exerted by a vapor in thermodynamic
equilibrium with its condensed phases. Boiling occurs when:
A. Vapor pressure exceeds dynamic pressure
B. Saturation pressure is less than local pressure
C. Temperature reaches the triple point
, D. Local pressure drops below the vapor pressure
Answer: D
Conceptual Explanation: Boiling or cavitation occurs when the local liquid pressure falls
below the saturation (vapor) pressure at the given temperature.
5. Pascal’s Law states that in a fluid at rest, the pressure at a point:
A. Acts only in the downward direction
B. Is the same in all directions
C. Is proportional to the fluid’s velocity
D. Depends on the shape of the container
Answer: B
Conceptual Explanation: Pressure at any point in a fluid at rest has the same magnitude in
all directions.
6. For a completely submerged body, the buoyant force acts through which point?
A. Center of gravity of the body
B. Centroid of the displaced volume
C. The lowest point of the body
D. The metacenter
Answer: B
AND APPLICATIONS (CENGEL) -
COMPREHENSIVE EXAM QUESTIONS
AND ANSWERS
1. According to the no-slip condition, what is the velocity of a fluid in direct contact with a
solid surface?
A. Equal to the bulk velocity of the fluid
B. Dependent only on the fluid’s density
C. Infinite due to molecular friction
D. Zero relative to the solid surface
Answer: D
Conceptual Explanation: The no-slip condition states that a fluid in motion comes to a
complete stop at the surface and assumes the zero velocity of the surface.
2. Which dimensionless number represents the ratio of inertial forces to viscous forces?
A. Froude Number
B. Mach Number
,C. Weber Number
D. Reynolds Number
Answer: D
Conceptual Explanation: The Reynolds number (Re = rhoVL/mu) characterizes the flow
regime by comparing inertia to viscosity.
3. In a Newtonian fluid, the shear stress is linearly proportional to:
A. The pressure gradient
B. The velocity gradient perpendicular to the flow
C. The square of the velocity
D. The fluid density
Answer: B
Conceptual Explanation: For Newtonian fluids, shear stress is proportional to the strain
rate (velocity gradient) through the dynamic viscosity.
4. Vapor pressure is defined as the pressure exerted by a vapor in thermodynamic
equilibrium with its condensed phases. Boiling occurs when:
A. Vapor pressure exceeds dynamic pressure
B. Saturation pressure is less than local pressure
C. Temperature reaches the triple point
, D. Local pressure drops below the vapor pressure
Answer: D
Conceptual Explanation: Boiling or cavitation occurs when the local liquid pressure falls
below the saturation (vapor) pressure at the given temperature.
5. Pascal’s Law states that in a fluid at rest, the pressure at a point:
A. Acts only in the downward direction
B. Is the same in all directions
C. Is proportional to the fluid’s velocity
D. Depends on the shape of the container
Answer: B
Conceptual Explanation: Pressure at any point in a fluid at rest has the same magnitude in
all directions.
6. For a completely submerged body, the buoyant force acts through which point?
A. Center of gravity of the body
B. Centroid of the displaced volume
C. The lowest point of the body
D. The metacenter
Answer: B
