Fluid Mechanics Practice Exam
Questions and Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which property describes a fluid's resistance to deformation under shear
stress?
A. Density
B. Surface tension
C. Viscosity
D. Specific gravity
Answer: C
Rationale: Viscosity measures a fluid's internal resistance to flow or deformation
caused by shear forces. Highly viscous fluids, such as honey, resist motion more
than low-viscosity fluids such as water.
2. The SI unit of pressure is the:
A. Joule
B. Newton
C. Pascal
D. Watt
Answer: C
Rationale: Pressure is force per unit area, and its SI unit is the pascal (Pa), equal to
one newton per square meter (N/m²).
,3. Density is defined as:
A. Weight divided by volume
B. Force divided by area
C. Mass divided by volume
D. Volume divided by mass
Answer: C
Rationale: Density is the mass contained in a unit volume and is expressed as
ρ=mV\rho = \frac{m}{V}ρ=Vm.
4. The SI unit of dynamic viscosity is:
A. m²/s
B. Pa/m
C. Pa·s
D. kg/m²
Answer: C
Rationale: Dynamic viscosity is measured in pascal-seconds (Pa·s), which is
equivalent to N·s/m².
5. Specific gravity is the ratio of a substance's density to the density of:
A. Air at standard conditions
B. Mercury
C. Water at its reference condition
D. Seawater
Answer: C
Rationale: Specific gravity is a dimensionless quantity obtained by dividing the
density of a substance by the density of water under standard reference
conditions.
,6. A fluid at rest cannot sustain:
A. Normal stress
B. Hydrostatic pressure
C. Shear stress
D. Compressive stress
Answer: C
Rationale: In a static fluid, shear stresses vanish because any applied shear would
cause the fluid to deform continuously.
7. Hydrostatic pressure increases with:
A. Temperature only
B. Fluid color
C. Depth below the free surface
D. Container shape
Answer: C
Rationale: Hydrostatic pressure increases linearly with depth according to
P=ρghP=\rho ghP=ρgh.
8. Absolute pressure equals:
A. Gauge pressure minus atmospheric pressure
B. Vacuum pressure only
C. Gauge pressure plus atmospheric pressure
D. Atmospheric pressure minus gauge pressure
Answer: C
Rationale: Absolute pressure is measured relative to a perfect vacuum and equals
atmospheric pressure plus gauge pressure.
9. Gauge pressure is measured relative to:
, A. A perfect vacuum
B. Sea level elevation
C. Atmospheric pressure
D. Water vapor pressure
Answer: C
Rationale: Gauge pressure uses local atmospheric pressure as its reference point.
10. Atmospheric pressure at sea level is approximately:
A. 50 kPa
B. 101.3 kPa
C. 150 kPa
D. 250 kPa
Answer: B
Rationale: Standard atmospheric pressure at sea level is approximately 101.3 kPa.
11. Pascal's law states that pressure applied to a confined fluid is:
A. Lost due to viscosity
B. Applied only downward
C. Transmitted equally in all directions
D. Reduced with container size
Answer: C
Rationale: Pascal's law states that pressure applied to a confined fluid is
transmitted undiminished throughout the fluid.
12. The hydrostatic force on a submerged surface depends directly on:
A. Fluid color
B. Pipe diameter only
Questions and Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which property describes a fluid's resistance to deformation under shear
stress?
A. Density
B. Surface tension
C. Viscosity
D. Specific gravity
Answer: C
Rationale: Viscosity measures a fluid's internal resistance to flow or deformation
caused by shear forces. Highly viscous fluids, such as honey, resist motion more
than low-viscosity fluids such as water.
2. The SI unit of pressure is the:
A. Joule
B. Newton
C. Pascal
D. Watt
Answer: C
Rationale: Pressure is force per unit area, and its SI unit is the pascal (Pa), equal to
one newton per square meter (N/m²).
,3. Density is defined as:
A. Weight divided by volume
B. Force divided by area
C. Mass divided by volume
D. Volume divided by mass
Answer: C
Rationale: Density is the mass contained in a unit volume and is expressed as
ρ=mV\rho = \frac{m}{V}ρ=Vm.
4. The SI unit of dynamic viscosity is:
A. m²/s
B. Pa/m
C. Pa·s
D. kg/m²
Answer: C
Rationale: Dynamic viscosity is measured in pascal-seconds (Pa·s), which is
equivalent to N·s/m².
5. Specific gravity is the ratio of a substance's density to the density of:
A. Air at standard conditions
B. Mercury
C. Water at its reference condition
D. Seawater
Answer: C
Rationale: Specific gravity is a dimensionless quantity obtained by dividing the
density of a substance by the density of water under standard reference
conditions.
,6. A fluid at rest cannot sustain:
A. Normal stress
B. Hydrostatic pressure
C. Shear stress
D. Compressive stress
Answer: C
Rationale: In a static fluid, shear stresses vanish because any applied shear would
cause the fluid to deform continuously.
7. Hydrostatic pressure increases with:
A. Temperature only
B. Fluid color
C. Depth below the free surface
D. Container shape
Answer: C
Rationale: Hydrostatic pressure increases linearly with depth according to
P=ρghP=\rho ghP=ρgh.
8. Absolute pressure equals:
A. Gauge pressure minus atmospheric pressure
B. Vacuum pressure only
C. Gauge pressure plus atmospheric pressure
D. Atmospheric pressure minus gauge pressure
Answer: C
Rationale: Absolute pressure is measured relative to a perfect vacuum and equals
atmospheric pressure plus gauge pressure.
9. Gauge pressure is measured relative to:
, A. A perfect vacuum
B. Sea level elevation
C. Atmospheric pressure
D. Water vapor pressure
Answer: C
Rationale: Gauge pressure uses local atmospheric pressure as its reference point.
10. Atmospheric pressure at sea level is approximately:
A. 50 kPa
B. 101.3 kPa
C. 150 kPa
D. 250 kPa
Answer: B
Rationale: Standard atmospheric pressure at sea level is approximately 101.3 kPa.
11. Pascal's law states that pressure applied to a confined fluid is:
A. Lost due to viscosity
B. Applied only downward
C. Transmitted equally in all directions
D. Reduced with container size
Answer: C
Rationale: Pascal's law states that pressure applied to a confined fluid is
transmitted undiminished throughout the fluid.
12. The hydrostatic force on a submerged surface depends directly on:
A. Fluid color
B. Pipe diameter only
