FUNDAMENTALS OF FLUID MECHANICS EXAM with Questions and Answers/Plus a
Rationale Updated 2026 A+/Instant Download PDF
EXAM COVERAGE
1. Fluid Statics and Pressure Distribution
2. Integral Relations for a Control Volume
3. Differential Relations for Fluid Flow
4. Dimensional Analysis and Similitude
5. Viscous Flow in Pipes
6. Flow Over Immersed Bodies and Boundary Layers
7. Open-Channel Flow
8. Compressible Flow and Gas Dynamics
9. Turbomachinery and Pumps
1. A closed rigid tank contains a gas at high pressure. If the local gravitational acceleration
decreases by half while the mass and temperature of the gas remain constant, what happens to
the specific weight and density of the gas?
A. Both specific weight and density decrease by half.
B. Specific weight decreases by half, while density remains unchanged.
C. Specific weight remains unchanged, while density decreases by half.
D. Both specific weight and density remain unchanged.
CORRECT ANSWER : B
, Rationale: Density is mass per unit volume and is independent of gravity, whereas specific
weight is the product of density and gravitational acceleration ($\gamma = \rho g$). Therefore,
a reduction in gravity directly reduces the specific weight while leaving the fluid density
constant. Options A, C, and D incorrectly couple mass-density-gravity relationships.
2. An inverted U-tube manometer is used to measure the pressure difference between two water
pipes. If the manometric fluid is air, how does the sensitivity of this manometer compare to a
standard mercury-water U-tube manometer for the same pressure differential?
A. It is significantly less sensitive because air is much lighter than water.
B. It is significantly more sensitive because the density difference between water and air is
very small.
C. It has the exact same sensitivity since manometer sensitivity depends solely on pipe diameter.
D. It cannot measure pressure differences because air is compressible.
CORRECT ANSWER : B
Rationale: Manometer sensitivity increases as the density difference between the working fluid
and the manometric fluid decreases, leading to larger deflections for small pressure changes. Air
has a very small density compared to water, maximizing the deflection height. Options A, C, and
D misapply hydrostatic principles.
3. A submerged curved gate has a constant radius and extends into the page. When calculating the
horizontal component of the hydrostatic force on the gate, to what equivalent projected surface
area is this force always equal?
A. The actual curved surface area of the gate.
B. The vertical plane projection of the curved surface.
C. The horizontal plane projection of the curved surface.
D. The surface area of a hemisphere with the same radius.
CORRECT ANSWER : B
Rationale: The horizontal component of hydrostatic force on any arbitrary curved surface is
identically equal to the force acting on the vertical projection of that surface into a plane normal
to the force. Options A, C, and D confuse total surface geometry with vertical projection
requirements.
Rationale Updated 2026 A+/Instant Download PDF
EXAM COVERAGE
1. Fluid Statics and Pressure Distribution
2. Integral Relations for a Control Volume
3. Differential Relations for Fluid Flow
4. Dimensional Analysis and Similitude
5. Viscous Flow in Pipes
6. Flow Over Immersed Bodies and Boundary Layers
7. Open-Channel Flow
8. Compressible Flow and Gas Dynamics
9. Turbomachinery and Pumps
1. A closed rigid tank contains a gas at high pressure. If the local gravitational acceleration
decreases by half while the mass and temperature of the gas remain constant, what happens to
the specific weight and density of the gas?
A. Both specific weight and density decrease by half.
B. Specific weight decreases by half, while density remains unchanged.
C. Specific weight remains unchanged, while density decreases by half.
D. Both specific weight and density remain unchanged.
CORRECT ANSWER : B
, Rationale: Density is mass per unit volume and is independent of gravity, whereas specific
weight is the product of density and gravitational acceleration ($\gamma = \rho g$). Therefore,
a reduction in gravity directly reduces the specific weight while leaving the fluid density
constant. Options A, C, and D incorrectly couple mass-density-gravity relationships.
2. An inverted U-tube manometer is used to measure the pressure difference between two water
pipes. If the manometric fluid is air, how does the sensitivity of this manometer compare to a
standard mercury-water U-tube manometer for the same pressure differential?
A. It is significantly less sensitive because air is much lighter than water.
B. It is significantly more sensitive because the density difference between water and air is
very small.
C. It has the exact same sensitivity since manometer sensitivity depends solely on pipe diameter.
D. It cannot measure pressure differences because air is compressible.
CORRECT ANSWER : B
Rationale: Manometer sensitivity increases as the density difference between the working fluid
and the manometric fluid decreases, leading to larger deflections for small pressure changes. Air
has a very small density compared to water, maximizing the deflection height. Options A, C, and
D misapply hydrostatic principles.
3. A submerged curved gate has a constant radius and extends into the page. When calculating the
horizontal component of the hydrostatic force on the gate, to what equivalent projected surface
area is this force always equal?
A. The actual curved surface area of the gate.
B. The vertical plane projection of the curved surface.
C. The horizontal plane projection of the curved surface.
D. The surface area of a hemisphere with the same radius.
CORRECT ANSWER : B
Rationale: The horizontal component of hydrostatic force on any arbitrary curved surface is
identically equal to the force acting on the vertical projection of that surface into a plane normal
to the force. Options A, C, and D confuse total surface geometry with vertical projection
requirements.
