10 Most Asking Mechanical Engineering Interview Questions

1. What are compressible and incompressible flows ?

Ans:- compressible flow – variable density fluid flow .
Incompressible flow – fixed density fluid flow .

2. What are the different units of viscosity ?

Ans:- In SI – Kg (m.s) . In CGS slug (ft.s) . The values of viscosity is often very small so for that reason a more reasonable unit is used which is called cP or centipoise.

3. Which has higher COP ? Vapor compression or Vapor absorption  Explain ? 

Ans:- Vapor Compression has the higher COP. Generally the COP of Vapor compression ranges from 3-4 but COP of Vapor absorption is generally 1. It happens because COPvc = Refrigeration Work / Compressor Work . But COPabs = Refrigeration Effect / (generator work + pump work ) .

4. How Defrosting is done in a refrigerator ?

Ans:- Defrosting is done by stopping the compressor for a short time.

5. What are major and minor head losses in a fluid flow system?

Ans:- Major loss is known as the losses that occur in the pipes. Minor losses are head losses which occurs due to bends and elbows (additional parts in the straight pipe system).

6. What happens if gasoline is used in a Diesel engine?Diesel engine will work ?

Ans:- No, It will not work,as the Compression ratio of Petrol engine is 6 to 10 & that of Diesel engine
is 15 to 22. Thus on such high compression, gasoline gets highly compressed & it may blast.

7. What is the alloy of tin and lead?

Ans:- A tin and lead alloy is commonly called solder. Usually solder is a wire with a rosin core used for soldering. The rosin core acts as a flux.

8. Explain mechatronics?

Ans:- Mechatronics refers to the efficient and effective integration of mechanical systems and electronics. It is a blend of mechanics and electronics, and has come to mean the synergistic use of:
  1. precision engineering
  2. control theory
  3. computer science
  4. mathematics
  5. sensor technology, to design enhanced or “smart” products, processes and systems.

9. Which compression is usually used in a/c?

Ans:- Hermetically sealed reciprocating compressor .

10. Difference between tempering and annealing ?

Ans:- Annealing is a process in which workpiece is heated up to certain temperature to get desired changes in grain or micro-structure and then allowed to cool slowly in order to relieve the stresses during work treatment. While tempering is a process wherein hardness and elasticity or ductility can be regain by use of heating and cooling cycle till desired properties can be obtained.

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