Mechanical Engineering Interview Questions part 1 (With Answers)

Hello friends, science lovers and fellow mechanical engineers, In today’s article I will discuss some important but most basic questions about mechanical engineering. After all this site is all about basic mechanical engineering, right ?? šŸ˜‰ Its actually a small endeavor for the newly graduated engineers. I know it is arduousĀ to get a good job just after having your BSc. degree. I am intending to write a series of articles regardingĀ mechanical engineering interview questions and their answers. So let’s move on. :).

But first, have a look some of the Basic Mechanical Engineering Questions with answers for your written or interview exam preparation. These will be great for your viva preparation as well.


Mechanical Engineering Interview Questions

Viva questions for mechanical engineers

Ā Mechanical Engineering Interview Questions

  • What is Mechanical Engineering?

answer: Mechanical Engineering is the branch of engineering which deals with the designing, constructing, maintaining and manufacturing various mechanical systems.

  • What is the difference between machine and engine?

Answer:Ā  Engine converts heat energy to Mechanical Energy but machine converts all forms of energy to mechanical energy except heat energy.

  • What is viscosity? What is Newton’s law of viscosity?

answer: Viscosity is the property of the fluid which measures the resistance of the fluid to the gradual deformation due to the shear stress.

Newtons Law of Viscosity states that: the shear stress on the fluid is proportional to the velocity gradient.

  • What are Newtonian and non-newtonian fluids ? Give examples.

answer: Newtonian fluids follow the newtons law of viscosity and non-newtonian fluids do not follow the law.

Newtonian fluid: Water, air, etc. Non-Newtonian Fluid: blood, tar, paste, etc.

  • What is Pump? What is a turbine? / What is the difference between the turbine and the pump?

answer: Pump is a device which transfers mechanical energy to the fluid. The turbine does the opposite. It transfers the flow energy of the fluid to mechanical energy.

  • What are turbo machines?

answer: Turbomachines are devices which transfer energy to or from the fluid by the dynamic action of rotating blades.

  • How the characteristics of a flow is determined?

answer: By Reynolds Number. If Re <2300 then the flow is laminar. if 2300 <Re<4000 then the flow is transient and if Re>4000 then the flow is turbulent.

  • What is the Reynolds number?

answer: Reynolds Number is the ratio of inertia force to viscous force. Re =Ā ĻvL/Ī¼

  • What is Bernoulliā€™s equation? Why it is used?

answer: pressure head + velocity head + datum head = constant

P1/Ī³Ā + (v2 )1/2g + z1 = P2/Ī³ +( v2)2 /2g + z1 = constant

  • What is the difference between the centrifugal pump and +ve displacement pump?

answer: In Centrifugal pump the flow rate changes with the head but in a positive displacement pump the flow rate remains the same.

  • What is cavitation in centrifugal pump? Why priming is done in centrifugal pump?

answer: If the suction side develops a pressure less than the vapor pressure of the water then water will start to boil and create water bubbles and it will spoil the impeller material. It is called cavitation.

When the impeller rotates it adds a rotating motion to the adjacent fluid and as a result, K.E and Pressure in the fluid increases and negative pressure are developed in the suction side of the impeller. So water/fluid flows continuously through the impeller. But when the pipe is filled with air, the impeller rotates but the pressure difference is negligible as a result no water flows through the pump. That’s why priming is done.

  • What is the difference between the heat engine & heat pump?

answer: Heat Engine produces work and transfers energy from high temp. to low temp source medium. In a Heat pump, external work is needed to transfer energy from low to high temp. medium.

  • What is the difference between an Impulse Turbine and Reaction Turbine?

Answer: In Impulse Turbine, all the pressure energy is converted to kinetic energy but in reaction turbine, a part of the pressure energy is converted to kinetic energy and rest remains as pressure energy.

  • What is NPSH?

Answer:Ā  NPSH = Net Positive Suction Head. It is the measure of minimum pressure which is required at the suction pipe to keep the pump from cavitation.

  • What is draft tube?

Answer: The draft tube is a conduit used in reaction turbine. The main feature of the draft tube is, it has a shape of increasing area at the end like a diffuser. You have know the classification and uses of draft tube if you are working in a hydraulic power plant.

That’s it for today mechanical engineers. Keep following basic mechanical engineering and you will get more info about mechanical engineering questions. mechanical engineering interview questions part 2 is coming up (see the link on the top). If you like/dislike the article please comment and let me know your thoughts.





Basic Mechanical Engineering is a small endeavor for the mechanical engineering students and fresh graduates. All the articles are written by mechanical "rocking" engineers \m/

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