Principles and Practice of Mechanical
Engineering Examination Questions With
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. In a steady-flow system, the First Law of Thermodynamics states
that:
A. Energy can be created
B. Entropy remains constant
C. The net energy entering equals the net energy leaving plus
accumulation
D. Heat transfer is always zero
Answer: C
Rationale: The First Law of Thermodynamics is an energy conservation
principle. For a steady-flow system, energy entering the control
volume equals energy leaving the control volume plus any
accumulation. Under steady-state conditions, accumulation is zero,
simplifying the energy balance.
, 2. Which thermodynamic process occurs at constant pressure?
A. Isochoric
B. Isothermal
C. Adiabatic
D. Isobaric
Answer: D
Rationale: An isobaric process occurs at constant pressure. Common
examples include heating water in an open container where
atmospheric pressure remains essentially constant throughout the
process.
3. The efficiency of a Carnot engine depends on:
A. Working fluid only
B. Engine size
C. Temperature limits of operation
D. Fuel type
Answer: C
Rationale: Carnot efficiency is determined solely by the temperatures
of the hot and cold reservoirs. It represents the theoretical maximum
,efficiency attainable by any heat engine operating between those
temperatures.
4. What is the SI unit of dynamic viscosity?
A. Pa·s
B. N/m
C. m²/s
D. J/kg
Answer: A
Rationale: Dynamic viscosity is measured in pascal-seconds (Pa·s). It
represents a fluid's resistance to deformation under shear stress.
5. Reynolds number is used to predict:
A. Heat transfer rates
B. Fluid flow regime
C. Pressure measurement accuracy
D. Specific gravity
Answer: B
, Rationale: Reynolds number compares inertial forces to viscous forces
in a fluid. It helps determine whether flow is laminar, transitional, or
turbulent.
6. Bernoulli's equation is based primarily on conservation of:
A. Mass
B. Momentum
C. Energy
D. Entropy
Answer: C
Rationale: Bernoulli's equation is derived from conservation of
mechanical energy along a streamline and relates pressure, velocity,
and elevation.
7. Which pump is classified as a positive displacement pump?
A. Centrifugal pump
B. Axial-flow pump
C. Gear pump
D. Mixed-flow pump
Answer: C
Engineering Examination Questions With
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. In a steady-flow system, the First Law of Thermodynamics states
that:
A. Energy can be created
B. Entropy remains constant
C. The net energy entering equals the net energy leaving plus
accumulation
D. Heat transfer is always zero
Answer: C
Rationale: The First Law of Thermodynamics is an energy conservation
principle. For a steady-flow system, energy entering the control
volume equals energy leaving the control volume plus any
accumulation. Under steady-state conditions, accumulation is zero,
simplifying the energy balance.
, 2. Which thermodynamic process occurs at constant pressure?
A. Isochoric
B. Isothermal
C. Adiabatic
D. Isobaric
Answer: D
Rationale: An isobaric process occurs at constant pressure. Common
examples include heating water in an open container where
atmospheric pressure remains essentially constant throughout the
process.
3. The efficiency of a Carnot engine depends on:
A. Working fluid only
B. Engine size
C. Temperature limits of operation
D. Fuel type
Answer: C
Rationale: Carnot efficiency is determined solely by the temperatures
of the hot and cold reservoirs. It represents the theoretical maximum
,efficiency attainable by any heat engine operating between those
temperatures.
4. What is the SI unit of dynamic viscosity?
A. Pa·s
B. N/m
C. m²/s
D. J/kg
Answer: A
Rationale: Dynamic viscosity is measured in pascal-seconds (Pa·s). It
represents a fluid's resistance to deformation under shear stress.
5. Reynolds number is used to predict:
A. Heat transfer rates
B. Fluid flow regime
C. Pressure measurement accuracy
D. Specific gravity
Answer: B
, Rationale: Reynolds number compares inertial forces to viscous forces
in a fluid. It helps determine whether flow is laminar, transitional, or
turbulent.
6. Bernoulli's equation is based primarily on conservation of:
A. Mass
B. Momentum
C. Energy
D. Entropy
Answer: C
Rationale: Bernoulli's equation is derived from conservation of
mechanical energy along a streamline and relates pressure, velocity,
and elevation.
7. Which pump is classified as a positive displacement pump?
A. Centrifugal pump
B. Axial-flow pump
C. Gear pump
D. Mixed-flow pump
Answer: C
