Technical practice questions
Mechanical Engineering Interview Questions
Real Mechanical Engineering interview questions with answers. Filter by sub-field and difficulty, then drill them in practice mode.
Showing 59 of 59 questions
Beginner
Fundamentals, definitions, expected of any candidate
Intermediate
Applied reasoning, design tradeoffs, calculations
Advanced
Deeper scenario / system-design questions and edge cases (stretch material)
BeginnerFundamentals
What's the difference between stress and strain?
fundamental knowledgestressstrainYoung's modulus
BeginnerFundamentals
How do you determine a factor of safety and why does it matter?
fundamental knowledgefactor of safetydesign margin
BeginnerFundamentals
State the three laws of thermodynamics and give an engineering application.
fundamental knowledgethermodynamicsenergy balance
BeginnerFundamentals
Explain shear force and bending moment diagrams for a simply supported beam.
fundamental knowledgebeamsbending momentshear
BeginnerFundamentals
Difference between ductile and brittle failure, and yield vs. ultimate strength?
fundamental knowledgeductilebrittleyieldultimate
BeginnerFundamentals
What is fatigue and how do you design against it?
fundamental knowledgefatigueS-N curvestress concentration
BeginnerFundamentals
What is moment of inertia (second moment of area) and why does it matter in bending?
fundamental knowledgemoment of inertiabending stiffness
BeginnerFundamentals
What are the three fundamental conservation laws in mechanics?
fundamental knowledgeconservationmassmomentumenergy
BeginnerFundamentals
State Newton's three laws and give an engineering example.
fundamental knowledgeNewton's lawsstaticsdynamics
BeginnerFundamentals
What is entropy and what does the second law of thermodynamics say?
fundamental knowledgeentropysecond lawirreversibility
BeginnerFundamentals
Difference between an open, closed, and isolated system?
fundamental knowledgeopen systemclosed systemcontrol volume
BeginnerFundamentals
What is the Carnot cycle and why can't real engines reach its efficiency?
fundamental knowledgeCarnot cycleefficiencyreservoirs
BeginnerFundamentals
Compare laminar and turbulent flow.
fundamental knowledgelaminarturbulentReynolds number
BeginnerFundamentals
What are the main types of bearings and what does a bearing do?
fundamental knowledgebearingsfrictionmachine design
IntermediateCAD & Manufacturing
What is GD&T and why do interviewers care about it?
GD&TASME Y14.5datumstolerancing
AdvancedCAD & Manufacturing
What is tolerance stack-up and how do you analyze it?
tolerance stack-upworst-caseRSSassembly
IntermediateCAD & Manufacturing
How do you approach material selection (e.g., stainless vs. carbon steel, aluminum)?
material selectionDFMtradeoffs
IntermediateCAD & Manufacturing
You're handed a failing product from the field, what's your first step?
root causeDFMEAtroubleshooting
IntermediateRobotics
What's the difference between forward and inverse kinematics?
kinematicsforwardinverseend-effector
IntermediateRobotics
How do you decide between stepper and servo motors for an actuator?
actuatorsstepperservoclosed-loop
AdvancedRobotics
What mechanical design challenges are specific to robots?
robot designlightweightingcompliancethermal
BeginnerThermal Systems
Name the three modes of heat transfer with an equation for each.
heat transferconductionconvectionradiation
IntermediateThermal Systems
What is the Reynolds number and why does it matter?
Reynolds numberlaminarturbulentflow regime
AdvancedThermal Systems
How do you size a heat exchanger?
heat exchangerLMTDU-valuesizing
BeginnerMEP (HVAC Systems)
What's the first step in designing an HVAC system?
HVACload calculationsizingCFM
IntermediateMEP (HVAC Systems)
Walk through the vapor-compression refrigeration cycle.
refrigeration cyclevapor compressionCOP
IntermediateMEP (HVAC Systems)
Explain COP vs. EER vs. SEER.
COPEERSEERefficiency
AdvancedMEP (HVAC Systems)
What is psychrometrics and why does an HVAC engineer use it?
psychrometricshumiditydew pointcomfort
IntermediateMEP (Plumbing Systems)
How do you size a plumbing supply line?
plumbingfixture unitspipe sizingpressure
BeginnerMEP (Plumbing Systems)
What is a trap seal and why does every fixture need one?
plumbingtrap sealventingdrainage
IntermediateMEP (Plumbing Systems)
Why is drainage venting important?
plumbingventingDWVsiphonage
IntermediateAutomotive (Powertrain)
Compare the Otto and Diesel cycles.
Otto cycleDiesel cyclethermal efficiency
BeginnerAutomotive (Powertrain)
What's the difference between torque and power in an engine?
torquepowerenginerpm
AdvancedAutomotive (Powertrain)
How does EV thermal management differ from ICE cooling?
EVbattery thermalcooling loopsheat pump
IntermediateAutomotive (Chassis & Suspension)
What do springs and dampers each do in a suspension?
suspensionspring ratedampingride/handling
IntermediateAutomotive (Chassis & Suspension)
Explain understeer vs. oversteer.
vehicle dynamicsundersteeroversteerbalance
AdvancedAutomotive (Chassis & Suspension)
How does an anti-roll (sway) bar affect handling?
anti-roll barroll stiffnessbalance tuning
BeginnerFundamentals
What is the difference between work and power?
fundamental knowledgeworkpowerenergyrate
BeginnerFundamentals
Walk me through conserving energy (reducing heat loss/gain) in a room.
fundamental knowledgeenergy conservationinsulationheat transfercontrol volume
AdvancedThermal Systems
I have a PCB that runs hot. Walk me through designing the enclosure.
PCB thermalenclosure designconductionconvectionheatsink
BeginnerCAD & Manufacturing
You have two balls of identical size and shape, one steel and one aluminum. How do you tell them apart?
densitymaterial identificationsteel vs aluminumreasoning
BeginnerCAD & Manufacturing
A river crossing: your tire blows, and while changing it all three of that wheel's lug nuts fall into the river. No cell reception. What do you do?
problem-solvinglateral thinkingresourcefulness
IntermediateAutomotive (Powertrain)
You have a gear driven by an input torque. What can you do to increase the output torque?
gear ratiotorque multiplicationreductiontradeoff
IntermediateCAD & Manufacturing
A steel beam and an aluminum beam of identical geometry get the same load (flat plate across). Which sees the higher stress?
bending stressgeometry vs materialYoung's modulusdeflection
IntermediateCAD & Manufacturing
Describe the stress-strain curve of aluminum compared to steel.
stress-strain curvesteel vs aluminumyieldendurance limit
IntermediateMEP (Plumbing Systems)
What is the pressure in a pipe with one open end and one bend?
pipe pressureBernoullihydrostatic headminor lossbend
IntermediateOil & Gas
What does ASME Section VIII cover?
ASME Section VIIIpressure vesselcodeBPVC
IntermediateOil & Gas
What is ASME B31.3 and what does it govern?
ASME B31.3process pipingwall thicknessB31 family
IntermediateOil & Gas
What is API 510?
API 510pressure vessel inspectionremaining lifeMAWP
IntermediateOil & Gas
What is API 570?
API 570piping inspectioncorrosion rateTML
AdvancedOil & Gas
How do you calculate corrosion rate and remaining life of a pipe (per API 570 / B31.3)?
corrosion rateremaining lifeminimum thicknessinspection interval
AdvancedOil & Gas
What common damage mechanisms affect refinery equipment?
damage mechanismscorrosionSCCsulfidationHTHARBI
IntermediateOil & Gas
What's the difference between hydrostatic and pneumatic pressure testing?
hydrostatic testpneumatic testpressure testingB31.3
BeginnerFundamentals
Explain the stress-strain curve, its key regions, and what happens during loading and unloading (elastic vs. plastic).
stress-strain curveelasticplasticyieldloading/unloading
BeginnerFundamentals
Explain shear force vs. bending moment, and how you'd calculate them for a simply supported beam under a uniformly distributed load (UDL).
shear forcebending momentUDLsimply supported beam
BeginnerFundamentals
How would you design a beam to minimize deflection under load?
deflectionmoment of inertiabeam designstiffness
IntermediateCAD & Manufacturing
How would you approach selecting the material for a specific mechanical component?
material selectionrequirementsAshby charttradeoffs
IntermediateCAD & Manufacturing
What are tolerances, how do you decide which are critical, and can you give an example where tolerances caused a manufacturing challenge?
tolerancescritical dimensionsstack-upGD&Tmanufacturing
IntermediateCAD & Manufacturing
How would you use numerical simulations (FEA/CFD) to streamline product development, and at what stages?
FEACFDsimulationproduct developmentvalidation