MELE Exam Flashcards

Q: What are the three MELE subjects and their official weights?

Machine Design, Material and Shop Practice at 30%, Industrial and Power Plant Engineering at 35%, and Mathematics, Engineering Economics and Basic Engineering Sciences at 35%, fixed by Section 24-II of the Implementing Rules of Republic Act No. 8495.

Q: How many questions are on the real examination?

The Board's Tables of Specifications allot 100 items to each of the three subjects, so 300 objective items in total. This set has 50 cards, which is a review allocation and not the examination itself.

Q: What score is required to pass the MELE?

Section 18 of Republic Act No. 8495 requires an average of 70% on all subjects with no rating below 50% in any subject, so a strong average cannot rescue one subject that falls under the 50% floor.

Q: How were the 50 cards distributed across the subjects?

By the statutory weights: 15 cards for Machine Design, Material and Shop Practice, 18 for Industrial and Power Plant Engineering, and 17 for Mathematics, Engineering Economics and Basic Engineering Sciences. Cards within each subject follow the item counts in the 2013 Tables of Specifications.

Q: What happens after a third unsuccessful attempt?

Section 20 of Republic Act No. 8495 allows another examination only after one year from the last examination taken. No waiting period is published for a first or second failure.

Q: When is the MELE given?

Twice a year under Section 25 of the Implementing Rules. The 2026 PRC schedule lists February 11, 12 and 13, 2026 and August 7, 8 and 9, 2026, with results targeted for February 19 and August 12, 2026.

Q: Is the MELE a computer-based licensure examination?

The 2026 PRC schedule does not carry the (CBLE) tag for Mechanical Engineers that it applies to Certified Plant Mechanics. Section 31 of the Implementing Rules refers to a computerized test-question data bank and computer correction of answer sheets rather than on-screen delivery.

Q: Where does mechanical engineering law appear on the blueprint?

Inside the Mathematics, Engineering Economics and Basic Engineering Sciences subject. Its Table of Specifications gives 15 items to Engineering Economics, ME Law and Code of Ethics, of which one item each covers the ME Law, the ME Code, the Code of Ethics, and Obligations and Contracts.

Question 1

Train value of a compound gear train

Accepted Answer

Train value = product of the driving gear teeth divided by product of the driven gear teeth. An idler placed between two gears reverses the direction of rotation but cancels out of the ratio, so adding one changes sense only, never speed.

Question 2

Grashof's criterion for a four-bar linkage

Accepted Answer

At least one link can fully rotate when S + L is less than or equal to P + Q, where S and L are the shortest and longest links. Fail the test and every link only oscillates, so no motor-driven crank is possible.

Question 3

Allowance versus tolerance in a fit

Accepted Answer

Allowance is the intended difference between mating parts at maximum material condition, so it is the minimum clearance or the maximum interference. Tolerance is only the permitted variation on one dimension. Allowance decides the type of fit; tolerance decides how much each part may drift.

Question 4

Soderberg equation for fluctuating stress

Accepted Answer

sigma_a / Se + sigma_m / Sy = 1 / N, where sigma_a is the alternating stress and sigma_m the mean stress. It anchors the design line on yield strength, making it the most conservative fatigue criterion; Goodman substitutes ultimate strength Su for Sy and permits a higher mean stress.

Question 5

Euler critical load for a column

Accepted Answer

Pcr = pi^2 x E x I / (K x L)^2, with K = 1.0 pinned-pinned, 0.5 fixed-fixed, 0.7 fixed-pinned and 2.0 fixed-free. Euler holds only for long columns; below the critical slenderness ratio the column yields before it buckles and an empirical formula such as J.B. Johnson applies.

Question 6

Throat of a fillet weld

Accepted Answer

Throat = 0.707 x leg size for an equal-leg fillet, and the shear area is throat x weld length. Sizing the weld on the leg dimension instead of the throat overstates its strength by about 41%.

Question 7

L10 rating life of a rolling-element bearing

Accepted Answer

L10 = (C / P)^k million revolutions, with k = 3 for ball bearings and 10/3 for roller bearings. L10 is the life that 90% of identical bearings reach, so doubling the load cuts ball-bearing life to about one-eighth.

Question 8

Ratio of belt tensions on a flat belt

Accepted Answer

F1 / F2 = e^(mu x theta) at the point of slipping, with theta the angle of contact in radians. Power transmitted = (F1 - F2) x belt speed, so increasing the wrap on the smaller pulley raises capacity without raising tight-side tension.

Question 9

Torque needed to develop a bolt preload

Accepted Answer

T = K x F x d, where K is the nut factor (about 0.20 as-received steel, 0.15 lubricated) and d is the nominal bolt diameter. K carries all the friction, so the same wrench torque on a lubricated bolt produces roughly a third more preload.

Question 10

Deflection of a helical compression spring

Accepted Answer

delta = 8 x F x D^3 x n / (G x d^4), with D the mean coil diameter, d the wire diameter and n the active coils. Deflection varies with the fourth power of wire diameter, so wire only 10% thicker makes the spring about 46% stiffer.

Question 11

PSME Code shafting formula for power capacity

Accepted Answer

P = D^3 x N / C horsepower, with D in inches, N in rpm, and C = 80 for main power-transmitting shafts, 53.5 for line shafts carrying pulleys, and 38 for small short shafts. The larger constant is the more conservative case: a main shaft carries extra bending, so the same diameter and speed are rated for less power than a short shaft.

Question 12

Force acting on a key that transmits torque

Accepted Answer

F = 2T / D at the shaft surface, where D is the shaft diameter. The key is then checked twice, in shear across width x length and in bearing on half the height x length, and the weaker of the two sets the required key length.

Question 13

Module, circular pitch and diametral pitch of a gear

Accepted Answer

Module m = D / N in millimetres, circular pitch p = pi x m, and diametral pitch Pd = N / D in teeth per inch. Two gears mesh only if they share the same module or diametral pitch, and p x Pd always equals pi.

Question 14

Tangential versus longitudinal stress in a thin-walled cylinder

Accepted Answer

Tangential (hoop) stress = p x D / (2t); longitudinal stress = p x D / (4t). Hoop stress is twice the longitudinal, which is why a pressurised pipe splits along its length rather than around its circumference.

Question 15

Cutting speed on a lathe or milling machine

Accepted Answer

V = pi x D x N, or V = pi x D x N / 1000 in m/min with D in millimetres. Cutting speed is dictated by the tool and workpiece material pair, so the machinist looks up V and solves for spindle speed N.

Question 16

Dulong's formula for the higher heating value of a fuel

Accepted Answer

HHV = 33,820C + 144,212(H - O/8) + 9,304S kJ/kg, with C, H, O and S as mass fractions. The O/8 term subtracts the hydrogen already bound as water in the fuel, so omitting it overstates the heating value.

Question 17

Load factor versus capacity factor of a power plant

Accepted Answer

Load factor = average load / peak load; capacity factor = average load / rated plant capacity. A plant can hold a high load factor while its capacity factor stays low, which is the signal that installed capacity exceeds the demand it serves.

Question 18

Why reheat is added to a Rankine cycle

Accepted Answer

Reheat returns partly expanded steam to the boiler and expands it a second time, raising turbine work while keeping exhaust moisture below roughly 12% to protect the last-stage blades. Regenerative feedwater heating is the different measure: it raises efficiency by warming feedwater with extraction steam.

Question 19

Mechanical efficiency of a reciprocating engine

Accepted Answer

Mechanical efficiency = brake power / indicated power. Indicated power comes from the cylinder pressure-volume diagram and brake power from the dynamometer; the gap is friction and auxiliary drive, so brake thermal efficiency is always the lower of the two thermal figures.

Question 20

Ideal Brayton cycle efficiency

Accepted Answer

eta = 1 - (1 / rp)^((k - 1) / k), where rp is the compressor pressure ratio. Efficiency depends on pressure ratio alone, not on turbine inlet temperature, although that temperature is what sets the net work the unit actually delivers.

Question 21

Power available from a hydroelectric site

Accepted Answer

Water power = rho x g x Q x H, then multiplied by turbine and generator efficiencies for plant output. H is the net head, so penstock friction must be deducted from gross head before the calculation.

Question 22

The three heat transfer laws

Accepted Answer

Conduction follows Fourier, Q = k x A x dT / L; convection follows Newton, Q = h x A x dT; radiation follows Stefan-Boltzmann, Q = e x sigma x A x T^4. Only radiation requires absolute temperature, so a Celsius value in that term is a guaranteed error.

Question 23

Affinity laws for pumps and fans

Accepted Answer

At a fixed impeller diameter, flow varies with speed, head with speed squared and power with speed cubed. Cutting speed by 20% therefore drops flow 20% but power about 49%, which is the whole argument for variable-speed drives over throttling.

Question 24

Injury frequency rate versus severity rate

Accepted Answer

Frequency rate = disabling injuries x 1,000,000 / employee-hours worked; severity rate = days charged x 1,000,000 / employee-hours worked. Frequency measures how often injuries occur, severity how much time each one costs, so a plant can improve one while the other worsens.

Question 25

Net positive suction head available at a pump

Accepted Answer

NPSHa = atmospheric head - vapour pressure head, plus or minus static suction head, minus suction friction head. Cavitation starts once NPSHa drops below the manufacturer's NPSHr, which is why hot liquids and long suction lines force the pump to be set lower.

Question 26

Static, velocity and total pressure in a fan system

Accepted Answer

Total pressure = static pressure + velocity pressure, and air power = volume flow x total pressure. Rating a fan on static pressure alone understates the work it does whenever the discharge velocity is significant.

Question 27

Optimum intercooler pressure for a two-stage compressor

Accepted Answer

Px = square root of (P1 x P2), which gives both stages the same pressure ratio and the same work. It assumes perfect intercooling back to suction temperature; without that, the ideal split shifts and total work rises.

Question 28

Cooling tower range versus approach

Accepted Answer

Range = hot water in minus cold water out; approach = cold water out minus entering air wet-bulb temperature. Range is set by the plant heat load, approach by tower size, and approach can never reach zero because the wet-bulb is the theoretical floor.

Question 29

One ton of refrigeration in SI units

Accepted Answer

1 TR = 3.516 kW = 211 kJ/min = 12,000 Btu/hr. It is defined as the cooling rate that freezes one short ton of water at 0 degC into ice in 24 hours, so it names a rate of heat removal, never a quantity of heat.

Question 30

Heat to be removed when making ice from water

Accepted Answer

Q = m x cp_water x (T - 0) + m x Lf + m x cp_ice x (0 - T_ice), with Lf = 335 kJ/kg, cp of water 4.187 and cp of ice 2.093 kJ/kg-K. The latent term dominates, so subcooling the ice a few degrees adds far less load than the freezing itself.

Question 31

When dry-bulb, wet-bulb and dew-point temperatures are equal

Accepted Answer

Only at saturation, where relative humidity is 100%. The wet-bulb depression, the gap between dry-bulb and wet-bulb, is what fixes the air's state on a psychrometric chart; a zero depression means the air can absorb no more moisture.

Question 32

Sensible heat factor of a cooling load

Accepted Answer

SHF = sensible heat / (sensible heat + latent heat). It sets the slope of the room process line on the psychrometric chart, so a low SHF from crowded rooms or kitchens calls for a coil that dehumidifies as much as it cools.

Question 33

Equal-friction method of duct design

Accepted Answer

Every run is sized for the same pressure drop per unit length, so velocity falls naturally toward the ends of the system. It does not self-balance runs of unequal length, so dampers or the static-regain method are still needed on long duct systems.

Question 34

Sum and product of the roots of ax^2 + bx + c = 0

Accepted Answer

Sum = -b / a and product = c / a. The discriminant b^2 - 4ac then classifies them: positive gives two distinct real roots, zero a repeated root, negative a conjugate complex pair.

Question 35

Remainder theorem and factor theorem

Accepted Answer

Dividing f(x) by (x - a) leaves the remainder f(a), and if f(a) = 0 then (x - a) is a factor. This turns root-hunting into simple evaluation, and synthetic division returns the remainder and the depressed polynomial in one pass.

Question 36

Logarithm identities used in board problems

Accepted Answer

log(MN) = log M + log N, log(M/N) = log M - log N, log(M^p) = p log M, and the change of base log_b M = ln M / ln b. Only the change-of-base rule lets a calculator evaluate bases other than 10 or e.

Question 37

Law of cosines and when it beats the law of sines

Accepted Answer

c^2 = a^2 + b^2 - 2ab cos C solves side-angle-side and side-side-side triangles. The law of sines, a / sin A = b / sin B, suits angle-angle-side but produces the ambiguous case for side-side-angle, where two triangles may satisfy the data.

Question 38

Special products worth memorising

Accepted Answer

a^2 - b^2 = (a - b)(a + b); a^3 - b^3 = (a - b)(a^2 + ab + b^2); a^3 + b^3 = (a + b)(a^2 - ab + b^2). In the cube forms the middle term's sign is opposite the binomial's, which is the detail most often reversed under time pressure.

Question 39

Prismatoid formula for volume

Accepted Answer

V = (h / 6)(A1 + 4Am + A2), where Am is the area of the mid-section, not the average of the two ends. One expression covers prisms, pyramids, frustums, cones and spheres, which makes it the fastest route through mensuration items.

Question 40

Distance from a point to a line

Accepted Answer

d = |A x0 + B y0 + C| / square root of (A^2 + B^2) for the line Ax + By + C = 0. Drop the absolute value and the sign reveals which side of the line the point lies on, which is also how the distance between two parallel lines is obtained.

Question 41

Nominal versus effective interest rate

Accepted Answer

Effective annual rate = (1 + r/m)^m - 1, with r the nominal annual rate and m the compounding periods per year. 12% compounded monthly is effectively 12.68%, so comparing alternatives on nominal rates understates the cost of frequent compounding.

Question 42

Comparing investment alternatives with unequal service lives

Accepted Answer

Either compare annual worth directly, or compare present worth over a study period equal to the least common multiple of the lives. Comparing present worths taken over different lives is the standard trap because it flatters the shorter-lived option.

Question 43

The three practice categories under Republic Act No. 8495

Accepted Answer

In rank order, Professional Mechanical Engineer, Mechanical Engineer, and Certified Plant Mechanic (Section 13). Only a Professional Mechanical Engineer may sign and seal mechanical designs, plans and specifications, and proposals for pressurised piping rated at 70 kPa or more (Sections 33 and 35).

Question 44

The mole and molar volume at standard conditions

Accepted Answer

One mole holds 6.022 x 10^23 particles and, for an ideal gas at 0 degC and 101.325 kPa, occupies 22.4 litres. That volume is tied to standard temperature and pressure; at 25 degC the same mole fills about 24.5 litres.

Question 45

Half-life and radioactive decay

Accepted Answer

N = N0 x (1/2)^(t / t_half), equivalently N = N0 x e^(-lambda t) with lambda = 0.693 / t_half. Decay is exponential, so activity approaches but never reaches zero, and no chemical or thermal treatment alters the half-life.

Question 46

Relationship among wave speed, frequency and wavelength

Accepted Answer

v = f x lambda. When a wave crosses into a new medium its frequency is unchanged because the source fixes it, while speed and wavelength both change, and that mismatch is what produces refraction.

Question 47

Speed of sound in air and the decibel scale

Accepted Answer

v is about 331 + 0.6t m/s with t in degrees Celsius, so roughly 343 m/s at 20 degC. Sound level in decibels = 10 log(I / I0) with I0 = 10^-12 W/m^2, so each 10 dB step is a tenfold change in intensity.

Question 48

Axial deformation of a bar under load

Accepted Answer

delta = P x L / (A x E), valid only below the proportional limit where Hooke's law holds. E is a material property and cannot be designed around, so doubling cross-sectional area halves the stretch while doubling the length doubles it.

Question 49

Carnot efficiency and what it limits

Accepted Answer

eta = 1 - TL / TH, with both temperatures absolute in kelvin or rankine. No engine operating between the same two reservoirs can beat it, so any computed efficiency above the Carnot value points to an arithmetic error or a Celsius temperature left unconverted.

Question 50

Bernoulli's equation in head form

Accepted Answer

p / (rho g) + v^2 / (2g) + z = constant along a streamline. It assumes steady, incompressible, frictionless flow, so real piping problems extend it into the energy equation by adding head loss hf plus any pump or turbine head.

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