# Mechanical Engineering Interview Questions

Last update: 16 Apr 2019, 27 Questions and Answers

### Most Frequently Asked Mechanical Engineering Interview Questions And Answers With Examples:

Mechanical engineering is one of the professional branches of engineering which deals with the application of the principles of Material Science and Physics. It is a discipline which has the purpose of manufacturing, analyzing, maintaining and designing od the mechanical systems. There are several factors which consist of the production and the usage of mechanical power and heat for the operation, designing and production of the tools and their respective machines. You need to learn mechanics, kinematics, thermodynamics, materials science, and structural analysis to ace the engineering branch.

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##### First Law

Law of Conservation of Energy or the first law of thermodynamics states that there is no creation or destruction of energy, but it can only be changed or transferred from one form to another.

##### The Second Law of Thermodynamics

Here in this law, it states that there is a rise in the isolated system’s entropy. It is because the systems evolve towards thermal equilibrium. It is the state where the system has maximum entropy. It means that there is a rise in the entropy of the universe, no decrease.

##### The Third Law of Thermodynamics

With the approaching of the temperature to absolute zero, the entropy of a system approaches a constant value as defined in the third law of thermodynamics. All the different ground states help in the determination of the entropy value.

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The material used in several types of electronic types is Ferrite. It is a ceramic-like material which contains magnetic properties and is used in permanent magnets, toroidal inductors, computer memory elements.

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The thickness of any fluid is known as viscosity. For example, honey has higher viscosity as compared to water. There are fluids with different densities, and things can change on considering this factor. The outcome of the interaction between the different molecules in a fluid can also be termed as viscosity as the molecular level. It is also known as friction between the molecules in the fluid. It is the energy needed for the fluid flow.

This is an important parameter as it affects heat generation in cylinders, bearings and gear sets. In the case of oils, viscosity determines the resistance flow.

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• Interference Fit
• Transition Fit
• Clearance Fit

You can easily get marks in this Mechanical engineering Interview Question by just naming the types of fits in mechanical engineering.

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The heat treatment is required for the hardened materials for improving their dimensional stability and toughness. They are usually tempered or stress relieved for obtaining enhanced mechanical properties. Examples are increased hardness or strength.

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S.no Projectile Trajectory
1. It is an object. It is the path an object which it follows by the time of coming under the gravity’s influence.
2. Examples can be a rocket payload, a BB pellet, a bullet, a rock. A rocket launched from the earth and traveling to reach the moon.
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Non-Newtonian Fluid was discovered by Sir Isaac Newton.

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The main principle of a pump is increasing the fluid’s pressure for providing the driving force needed for the appropriate flow. The pump used in the filter feed pump is a centrifugal pump.

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A turbine is a machine or a rotary mechanical device which is used for the extraction of the energy from the flowing fluid and then converting to be used into useful work. The working of the simple principle is with the help of the three propellers like blade around the rotors. These are to be connected to the main shaft which then spun the generator producing elasticity.

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A compressor is a machine that is used to give rise to the pressure of a gas minimizing the volume of the gas. It is a mechanical device which works as similar to that of pumps. One of the gas compressors is an air compressor.

##### Types of a compressor-
• Positive Displacement
• Rotary
• Reciprocating
• Dynamic
• Centrifugal
• Axial
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Sleeve and cotter joint are used for connecting two similar coaxial cylindrical rods. The name so because the joint contains sleeve and two wedge-shaped tapered cotters. Also, there has been a cut in the cylindrical rods and sleeve. The next step is cotter assembling into the slots.

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The gear ratio is calculated by simply dividing the teeth on the driven gear by the number of teeth on the driver gear.

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The transition of the ductile to brittle transition temperature depends on the composition of the metal. One of the examples of the temperature transition is steel. It is because of the drop in the temperature to 00 C

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Flow Characteristics are used for describing the relationship between the value stroke and value coefficient. It is a parameter which every throttling valve contains. It is also used for allowing a certain amount of flow via the valve. The rate of the particular percentage of the stroke is decided by the flow characteristic. In addition to this, it allows having control of the flow of the valve, an important factor for the throttling value and that in a predictable manner. Learn the basic concept of flow characteristic and work to crack the Mechanical engineering Interview Questions.

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##### Centrifugal Pump has the following attributes as compared to reciprocating pumps-
• It is simpler than it due to inlet and outlet and an impeller
• Smooth rotation of the impeller in the centrifugal pump
• Requires less floor space and capacity
• Easy and quick installation and maintenance
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An impulse reaction turbine is used for generating a high speed of the jet of water by converting the pressure of energy into kinetic energy through a nozzle. After that, the water jet strikes the turbine’s blades and then starts rotating it. One more characteristic is that there is a change in the pressure of the water when it passes the turbine.

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Hydraulic machines are the tools and the machines that utilize the fluid power of liquid for taking the required actions. This is the fluid which is used in heavy equipment as well as other types of medium. The fluid gets the pressure as per the resistance present after its transmission throughout the machine to other hydraulic cylinders and hydraulic motors.

Pneumatic machines are used for applying the fluid power by using a gaseous media under pressure for controlling, generating and transmitting the power with the help of compressed gas.

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• No requirement of the parallel shifts
• Simpler to use
• Very economical
• Lubrication-free
• Needless maintenance
• Damping out of noise and vibration
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An orthographic drawing is also known as an orthographic projection is used for representing a 3-D object with the help of 2-D views of the object. This drawing helps in visualizing the image from the front, top and side of the material.
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S.no Isometric drawing Orthographic drawing
1. It is a quasi 3d drawing It represents the 3-D object and adding 2-D views of the object.
2. There is no such thing here It shows you the true size of the object on the scale of 1:1
3. Help in better understanding of the object Used in doing the projects
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Nitrogen is used in welding because it causes porosity in carbon steels and counteracts oxidation, narrows the arc. It also helps in improving weld penetration and enhance arc temperature.

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It is a technique helpful in the transformation of an aluminum alloy into the objects with a definitive cross-sectional profile. Aluminum extrusion has a broad spectrum of uses.

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The toughness of an object is the amount of energy per unit volume that a material can absorb without fracturing. Method of toughness calculation is-

Find the area under a stress-strain curve that has to be drawn for that material. It is calculated by integration of the curve.

It is one of the most common Mechanical engineering Interview Questions.

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It is an ability of an object or material through which it can come back to its normal shape after going through stretches, compression.

##### Types
• Perfectly Elastic Demand (EP = ∞) ...
• Perfectly Inelastic Demand (EP = 0) ...
• Relatively Elastic Demand (EP> 1) ...
• Relatively Inelastic Demand (Ep< 1 ) ...
• Unitary Elastic Demand ( Ep = 1)
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