What questions should you ask a mechanical engineer to hire them? These questions will help you find out as much as you can about their skills and knowledge. Mechanical engineering is a challenging industry that requires mathematical intelligence, creative skills, and technical expertise.
One way to better understand your candidates’ knowledge is to use assessments such as the Mechanical Reasoning test. The test requires candidates to answer questions based on their knowledge of physics and mechanics.
Another crucial part of assessing applicants is the interview stage. But what questions should you ask?
Discover 70 interview questions for mechanical engineering roles, with sample answers to help you hire the right person.
Engineering mechanics is a core discipline in many engineering fields including civil mechanical, aerospace and biomedical engineering. It provides the fundamental principles that are necessary for analyzing static and dynamic effects in structural systems and components. Having a solid grasp of engineering mechanics is essential for any engineer which is why engineering mechanics questions are commonly asked in technical interviews.
In this article, we provide the top 50 engineering mechanics interview questions along with detailed answers to help you prepare for your next technical interview.
Basic Engineering Mechanics Interview Questions
Here are some common introductory engineering mechanics interview questions:
Q1: What is engineering mechanics?
Engineering mechanics is the application of mechanics principles to analyze static and dynamic effects in engineering systems and components. It provides mathematical models to predict the effects of forces and motions on physical systems.
Q2 What are the two main branches of engineering mechanics?
The two main branches of engineering mechanics are:
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Statics – deals with systems that are in static equilibrium where the sum of forces and moments equals zero. Examples include trusses, beams, frames, etc.
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Dynamics – deals with accelerated motion and systems that are out of equilibrium. Examples include particles, rigid bodies, mechanisms, vibrations, etc.
Q3: What are some common engineering mechanics topics?
Some common engineering mechanics topics include:
- Statics – equilibrium of particles, rigid bodies, trusses, frames, machines
- Dynamics – kinematics of particles, kinetics of particles, kinematics of rigid bodies, kinetics of rigid bodies
- Strength of Materials – simple stress and strain, torsion, bending, shear stresses, buckling
- Vibrations – free vibration, forced vibration, damping
Q4: What assumptions are made in engineering mechanics?
Some key assumptions made in engineering mechanics include:
- Rigid body – deformation within the body is neglected
- Constant temperature – thermal effects are negligible
- Continuous media – objects are modeled as continuous mass rather than discrete particles
- Linearity – properties do not change significantly with applied loads
Q5: What are the units of common mechanical properties?
- Force – Newtons (N)
- Moment – Newton-meters (N-m)
- Stress – Pascals (Pa)
- Strain – unitless (m/m)
- Modulus of elasticity – Pascals (Pa)
- Density – kg/m3
Statics Interview Questions
Statics is a key topic in engineering mechanics. Here are some common statics interview questions:
Q1: What is a free body diagram and why is it useful?
A free body diagram isolates a body and shows all external forces acting on it. This allows the equations of equilibrium (∑F=0 and ∑M=0) to be applied to determine reactions and internal loads.
Q2: How can you find the centroid of an object?
The centroid is the center of mass of an object. For a thin plate, it can be found by taking a moment about any axis. For a composite shape, break it into simple shapes, find each centroid, and take a weighted average.
Q3: What is a truss? What assumptions are made about it?
A truss is a structure made of slender members joined at their ends. Truss assumptions include:
- Loads applied only at joints
- Members are connected by frictionless pins
- Members only experience axial forces, no bending
Q4: How can you determine if a system is statically indeterminate?
If the number of unknown reactions exceeds the number of equilibrium equations, the system is statically indeterminate and needs additional equations.
Q5: What is the difference between a 3-force and 4-force member?
A 3-force member has reactions that prevent both translation and rotation. A 4-force member has four non-concurrent forces acting on it, allowing rotation.
Q6: How can you calculate the reactions of a simply supported beam?
Use ΣFy = 0 and ΣM at one support to generate two equations to solve for the two unknown reactions.
Dynamics Interview Questions
Here are some common dynamics interview questions:
Q1: What is the difference between kinematics and kinetics?
Kinematics deals with the geometry of motion while kinetics deals with the forces causing the motion. Kinematics describes the motion, kinetics explains why.
Q2: How can you describe the velocity and acceleration of a particle moving in a plane?
Use a position vector r to describe the location. Take derivatives to find velocity v and acceleration a. These are vectors with x and y components.
Q3: What is Newton’s Second Law and how is it applied to a particle?
Newton’s Second Law states that the net external force on a particle equals its mass times its acceleration (ΣF=ma). This relates the motion to the applied forces.
Q4: How can you analyze the kinetics of a rigid body translating and rotating in a plane?
Use ΣF=ma and ΣM=Iα to generate equations of motion. F and M are the net force and moment, a and α are the acceleration and angular acceleration.
Q5: What is the moment of inertia and how can you calculate it for basic shapes?
Moment of inertia (I) relates applied torque to angular acceleration. It can be calculated from the mass distribution. For simple shapes like a cylinder, it can be looked up based on its geometry.
Q6: What is the work-energy principle and when can you apply it?
The work-energy principle states that the net work done by external forces equals the change in kinetic energy. It can be applied to systems where conservative internal forces do no work.
Strength of Materials Interview Questions
Strength of materials deals with calculating stresses and deformations in materials. Here are some example questions:
Q1: What is Hooke’s Law and what does it relate?
Hooke’s Law states that stress is proportional to strain for small deformations. The constant of proportionality is the modulus of elasticity. It relates stress and strain.
Q2: How can you calculate normal and shear stresses in a beam under bending?
Use the flexure formula σ = Mc/I to calculate bending stress. The normal stress varies linearly with distance from the neutral axis. Shear stress can be calculated from VQ/It.
Q3: What is the difference between stress and strain?
Stress is the internal resistance forces in a material caused by an applied load. Strain is the deformation resulting from the applied stress.
Q4: What causes failure in a ductile vs. brittle material?
Ductile materials fail due to excessive yielding/deformation. Brittle materials fail due to crack propagation when the theoretical stress exceeds the ultimate strength.
Q5: How does torsional stress in a circular shaft vary with radius?
Torsional stress (τ) varies linearly with radius (r) according to τ=Tr/J. T is applied torque, J is torsion constant. Stress is highest on the outer surface.
Q6: What is the maximum shear stress theory for failure and how is it applied?
Maximum shear stress theory states failure occurs when the maximum shear stress exceeds the shear strength. It is conservative and commonly used for ductile materials.
Vibrations Interview Questions
Understanding vibrations is key for designing machinery and preventing failures. Here are some vibrations interview questions:
Q1: What is a natural frequency of vibration?
Natural frequency is the frequency at which a system will oscillate once set into motion. It depends on system properties like mass, stiffness, damping.
Q2: How can you model a SDOF mass-spring-damper system?
Use the equation F(t) = mẍ + cẋ + kx. F(t) is applied load, m is mass, c is damping, k is stiffness. Can be solved for free or forced vibration.
Q3: What is damping and how does it affect system response?
Damping provides an energy dissipation mechanism. It reduces amplitude and decreases settling time. Critical damping provides the fastest response without overshoot.
Q4: What is resonance and how can it be avoided?
Resonance occurs when frequency of applied load matches natural frequency. Leads to high oscillations. Can be avoided by operating outside natural frequencies of system.
Q5: How would you calculate modal frequencies and mode shapes for a multi-DOF system?
Use matrix methods to generate the system eigenvalue problem. The eigenvalues are modal frequencies and the eigenvectors are the mode shapes.
Q6: What factors cause vibrations in rotating machinery?
Unbalance, misalignment, looseness, rubbing, and turbulence can all cause vibrations in rotating machinery. Vibration analysis can help identify the root cause.
Concluding Thoughts
A strong grasp of engineering mechanics principles is crucial for any engineer working with structural systems or mechanical components. Mastering these fundamental engineering mechanics interview questions requires an understanding of key topics like statics, dynamics, strength of materials and vibrations. Preparing explanations for these common technical interview questions can help demonstrate your engineering mechanics compet
What computer programs do you use in mechanical engineering?
Strong candidates will be familiar with the most popular software tools used in engineering. They could provide examples of software that has helped them to complete specific tasks.
For example, mechanical engineers can use Solid Edge to make 3D designs, while MATLAB is used to solve equations and do mathematical analysis of chemicals or materials.
However, not all projects require using complex computer programs. Some candidates might prefer to use Microsoft Excel when documenting projects, for example.
Use a Microsoft Excel test to better understand your candidates’ technical skills and ability to perform basic calculations. This way, you can also determine whether they require any additional training when they join the company.
Would you rather lead design teams or follow others?
This question will help you determine whether the candidate is a potential leader. Some candidates have natural leadership capabilities when it comes to teamwork. They might want to delegate tasks and support those who are new or struggling.
Candidates who prefer to follow are also just as valuable. Followers tend to be open-minded and have strong communication skills. You can choose a candidate based on who you want to join your team, how they can help with upcoming design projects, and how well they fit with your company’s mission and vision.
You might want to give job applicants a Leadership and People Management test to see how well they can lead others on the job.
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