Philippine Mechanical Engineering Licensure Examination (MELE) — Questions and Answers

Question 1: In laser beam machining (LBM), the parameter most directly controlling the depth of material removed per pulse is:

Peak power density (irradiance) at the workpiece surface (Correct answer)
Wavelength of the laser source
Assist gas pressure
Beam diameter at the lens

Correct answer: Peak power density (irradiance) at the workpiece surface

Peak power density (W/cm²) determines whether the threshold for ablation, melting, or vaporization is exceeded and how deeply each pulse penetrates the material.

Question 2: What do you name a person's area of study if they research a fluid that is at rest?

Fluid Dynamics
Fluid Mechanics
Fluid Kinematics
Fluid Statics (Correct answer)

Correct answer: Fluid Statics

Fluid statics is the specific branch of fluid mechanics dedicated to the study of fluids at rest. It analyzes the forces exerted by fluids when there is no relative motion between fluid particles or between the fluid and its boundaries. This field focuses on concepts like pressure distribution, buoyancy, and hydrostatic forces in stationary fluids.

Question 3: Which phase transformation occurs when austenite is rapidly quenched to form a body-centered tetragonal structure in steel?

Martensite formation (Correct answer)
Ferrite formation
Bainite formation
Pearlite formation

Correct answer: Martensite formation

Rapid quenching of austenite traps carbon in the BCC iron lattice, distorting it into a BCT martensitic structure.

Question 4: The Diesel cycle differs from the Otto cycle in that heat addition occurs at constant:

Temperature
Pressure (Correct answer)
Volume
Entropy

Correct answer: Pressure

In the Diesel cycle, fuel injection and combustion occur at constant pressure, unlike the Otto cycle where heat is added at constant volume.

Question 5: What is the primary practical drawback of applying pure derivative (D-only) control action?

It increases steady-state error to infinity
It amplifies high-frequency measurement noise (Correct answer)
It makes the system response slower
It removes all damping from the response

Correct answer: It amplifies high-frequency measurement noise

Differentiation magnifies rapid signal changes, so a pure derivative controller greatly amplifies high-frequency noise present in measured outputs, making stand-alone D control impractical.

Question 6: A significant composite is GFRP. It represents

Graphite Fibre Reinforced Polymer
Glass Fibre Reinforced Polymer (Correct answer)
Gelatin Fibre Reinforced Polymer
Germanium Fibre Reinforced Polymer

Correct answer: Glass Fibre Reinforced Polymer

GFRP is a widely recognized composite material used in various engineering applications. The acronym GFRP stands for Glass Fibre Reinforced Polymer. It consists of high-strength glass fibers embedded within a polymer matrix, combining the benefits of both materials to create a strong, lightweight, and versatile composite.

Question 7: The equation of motion for a viscously damped SDOF system under harmonic excitation is:

mẍ + kx = F₀sin(ωt)
mẍ + cẋ + kx = F₀sin(ωt) (Correct answer)
mẍ + kx = 0
cẋ + kx = F₀

Correct answer: mẍ + cẋ + kx = F₀sin(ωt)

A single degree-of-freedom system with mass m, damping c, and stiffness k under harmonic forcing F₀sin(ωt) is governed by mẍ + cẋ + kx = F₀sin(ωt).

Question 8: A bill of materials (BOM) in a CAD assembly drawing lists:

Tolerance stack-up calculations
Manufacturing steps only
All component parts with quantities, part numbers, and descriptions (Correct answer)
Surface finish specifications

Correct answer: All component parts with quantities, part numbers, and descriptions

A BOM is a structured list of all components in an assembly, including item numbers, quantities, part numbers, descriptions, and often material and supplier information.

Question 9: Entropy generation during an irreversible process is always:

Negative
Zero
Equal to heat transfer divided by temperature
Positive (Correct answer)

Correct answer: Positive

The Second Law requires that entropy generation S_gen > 0 for any irreversible process; it is zero only for reversible processes.

Question 10: The strain energy density for a linear elastic body under uniaxial stress σ is:

σ²/(2E) (Correct answer)
σε
Eε²
σ/(2E)

Correct answer: σ²/(2E)

Strain energy density u = σ²/(2E) = Eε²/2, representing the area under the linear elastic stress-strain curve.

Question 11: For a blackbody, the emissivity (ε) equals:

0
1 (Correct answer)
0.5
Depends on temperature

Correct answer: 1

A blackbody is an ideal perfect emitter and absorber, defined by emissivity ε = 1; real surfaces have ε < 1.

Question 12: Cavitation in hydraulic machinery occurs when the local fluid pressure drops below the:

Stagnation pressure
Vapor pressure of the fluid (Correct answer)
Atmospheric pressure
Critical pressure of the fluid

Correct answer: Vapor pressure of the fluid

Cavitation occurs when local static pressure falls below the fluid's vapor pressure, causing vapor bubble formation.

Question 13: Which turning operation produces an internal cylindrical surface?

Boring (Correct answer)
Threading
Knurling
Facing

Correct answer: Boring

Boring uses a single-point tool to enlarge or finish an existing hole, producing an accurate internal cylindrical surface.

Question 14: What exactly is model testing?

Performance testing (Correct answer)
Overall testing
Function testing
Partial testing

Correct answer: Performance testing

Model testing in fluid mechanics involves creating scaled-down versions of real-world systems (like aircraft, ships, or hydraulic structures) to predict their behavior. The primary purpose of these tests is to evaluate and predict the performance characteristics of the full-scale prototype under various operating conditions. This allows for design optimization and validation before full-scale construction.

Question 15: Which ceramic failure mode is associated with slow crack growth under sustained static loading below the fracture toughness?

Ductile fracture
Static fatigue (stress corrosion cracking) (Correct answer)
Fatigue fracture
Creep rupture

Correct answer: Static fatigue (stress corrosion cracking)

Static fatigue in ceramics involves subcritical crack growth driven by chemical attack at crack tips under sustained stress.

Question 16: In a Francis turbine, the guide vanes (wicket gates) are adjustable primarily to:

Control the flow rate and thus regulate power output (Correct answer)
Change the direction of the tailrace flow
Align the draft tube with the runner exit
Prevent cavitation at the runner inlet

Correct answer: Control the flow rate and thus regulate power output

Adjustable wicket gates vary the angle and quantity of water entering the runner, allowing the turbine output to be regulated to match load demand.

Question 17: In statistical process control (SPC), a process is considered 'out of control' when:

The sample size exceeds 30 measurements
A data point falls outside the control limits or a non-random pattern is detected (Correct answer)
All points fall within the 3-sigma control limits
The process Cpk exceeds 1.33

Correct answer: A data point falls outside the control limits or a non-random pattern is detected

An out-of-control signal occurs when points exceed 3-sigma limits or when non-random patterns (runs, trends) indicate special cause variation.

Question 18: In electrical discharge machining (EDM), material removal is achieved by:

Laser ablation through a conductive medium
Mechanical abrasion from a conductive wheel
Chemical dissolution in electrolyte
Controlled electrical sparks eroding the workpiece (Correct answer)

Correct answer: Controlled electrical sparks eroding the workpiece

EDM removes material through rapid electrical discharges (sparks) between the electrode and workpiece, vaporizing small amounts of material.

Question 19: Argon has an isobar of calcium. They vary in:

Number of nucleons
Atomic weight
None of the mentioned
Number of neutrons (Correct answer)

Correct answer: Number of neutrons

Isobars are atoms of different chemical elements that have the same mass number (total number of protons and neutrons). Since Argon and Calcium are distinct elements, they must have different numbers of protons. For them to share the same mass number, their number of neutrons must necessarily differ to compensate for the varying proton counts. For example, Argon-40 has 18 protons and 22 neutrons, while Calcium-40 has 20 protons and 20 neutrons.

Question 20: In a bolted joint under tensile load, which failure mode is checked first?

Tensile failure of the bolt shank (Correct answer)
Shear failure of the nut
Bearing failure
Bending failure

Correct answer: Tensile failure of the bolt shank

Tensile failure of the bolt shank is the most critical and commonly checked failure mode in bolted joints under direct tensile loading.

Question 21: In journal bearing design, the Sommerfeld number represents:

Bearing load capacity
A dimensionless parameter relating speed, viscosity, load, and geometry (Correct answer)
Friction force
Oil film temperature

Correct answer: A dimensionless parameter relating speed, viscosity, load, and geometry

The Sommerfeld number is a dimensionless bearing parameter combining viscosity, speed, load, and bearing geometry used to predict performance.

Question 22: In a fin, the efficiency is defined as the ratio of actual heat transfer to:

Heat transferred by the base without fin
Maximum possible heat transfer if the entire fin were at base temperature (Correct answer)
Heat transferred by radiation
Heat stored in the fin

Correct answer: Maximum possible heat transfer if the entire fin were at base temperature

Fin efficiency compares actual heat transfer to the ideal case where the whole fin surface is at the base (maximum) temperature.

Question 23: Spiral casing is seen in radial flow reaction turbines and it has the following area:

Gradually decreases (Correct answer)
Gradually increases
Suddenly decreases
Remains constant

Correct answer: Gradually decreases

The spiral casing, or volute casing, in radial flow reaction turbines is designed with a gradually decreasing cross-sectional area along its length. This design ensures that the water maintains a relatively constant velocity as it flows around the runner towards the guide vanes. By gradually decreasing the area, it helps to distribute the water uniformly around the runner periphery and convert pressure energy into kinetic energy efficiently before the water enters the guide vanes.

Question 24: The 'no-slip condition' in viscous fluid mechanics states that:

Density is constant near the boundary layer
The fluid velocity at a solid wall equals the wall velocity (Correct answer)
Turbulent fluctuations vanish at the wall
Pressure is continuous across a solid boundary

Correct answer: The fluid velocity at a solid wall equals the wall velocity

The no-slip condition requires that viscous fluid immediately adjacent to a solid surface moves at the same velocity as the surface.

Question 25: What statement about polymers is accurate?

They do not have a linear stress-strain curve
They have very high molecular mass
All of the mentioned (Correct answer)
They have high strength to mass ratio

Correct answer: All of the mentioned

Polymers are macromolecules characterized by very high molecular masses due to their long, repeating chain structures. Their mechanical behavior often exhibits a non-linear stress-strain curve, reflecting their viscoelastic nature. Additionally, many polymers, especially in composite forms, offer an excellent strength-to-mass ratio, making them ideal for lightweight, high-performance applications. Thus, all the statements accurately describe characteristics of polymers.

Question 26: A species' atomic number is the sum of its:

Neutrons
Nucleons
Protons (Correct answer)
Valence electrons

Correct answer: Protons

The atomic number of an element is fundamentally defined by the number of protons present in the nucleus of an atom. This number is unique to each element and dictates its chemical identity and position on the periodic table. The number of neutrons can vary (isotopes), and valence electrons are only the outermost electrons, not the defining characteristic of the atomic number.

Question 27: Castigliano's second theorem states that the partial derivative of strain energy U with respect to a force P equals:

The reaction force at the support
The bending moment due to P
The stress at the point of load application
The deflection at the point and in the direction of P (Correct answer)

Correct answer: The deflection at the point and in the direction of P

Castigliano's second theorem: δ = ∂U/∂P, giving the displacement at the load's point of application in the direction of the load.

Question 28: The volumetric efficiency of a pump accounts for:

Internal recirculation and leakage reducing useful discharge (Correct answer)
Bearing and seal mechanical losses
Hydraulic losses in the suction pipe
Friction losses in the impeller passages

Correct answer: Internal recirculation and leakage reducing useful discharge

Volumetric efficiency = Q_actual / Q_theoretical, capturing losses due to internal leakage past wearing rings and back through clearances rather than hydraulic or mechanical losses.

Question 29: Which statement correctly describes the difference between Newtonian and non-Newtonian fluids?

Newtonian fluids have viscosity that varies with shear rate; non-Newtonian fluids do not
Non-Newtonian fluids obey Bernoulli's equation; Newtonian fluids do not
Newtonian fluids have constant viscosity; non-Newtonian fluids have viscosity that depends on shear rate (Correct answer)
Newtonian fluids are always turbulent; non-Newtonian fluids are always laminar

Correct answer: Newtonian fluids have constant viscosity; non-Newtonian fluids have viscosity that depends on shear rate

Newtonian fluids have a linear stress–strain rate relationship (constant μ); non-Newtonian fluids (e.g., blood, paint) exhibit shear-dependent viscosity.

Question 30: Fourier's law of heat conduction states that heat flux is proportional to:

Temperature
Specific heat
Temperature gradient (Correct answer)
Thermal diffusivity

Correct answer: Temperature gradient

Fourier's law states q = -k(dT/dx), meaning heat flux is directly proportional to the negative temperature gradient.

Question 31: The category of a hydraulic coupling is .

Energy generating machines
Energy transfer machines (Correct answer)
Power absorbing machines
Energy absorbing machines

Correct answer: Energy transfer machines

A hydraulic coupling is a device used to transmit rotational mechanical power. It functions by transferring kinetic energy from a rotating input shaft (impeller) to an output shaft (turbine) via a fluid, typically oil. Therefore, it falls under the category of energy transfer machines, as it facilitates the movement of energy from one component to another without generating or absorbing it in a net sense.

Philippine Mechanical Engineering Licensure Examination (MELE)

The Philippine Mechanical Engineering Licensure Examination (MELE) is administered by the Professional Regulation Commission (PRC) and tests BME graduates across Mathematics/Engineering Sciences, Power/Industrial Plant Engineering, and Machine Design to earn the Registered Mechanical Engineer (RME) license.

100

Questions

150 min

Time Limit

70%

To Pass

Checking for saved progress...

Exam Rules

You can skip questions and return to them later
Flag questions for review before submitting
No feedback shown until you submit the entire exam
Unanswered questions count as wrong — answer everything
10 pretest questions are mixed in and don't affect your score
Timer auto-submits when time runs out
Your progress is auto-saved every 30 seconds