25 Best Mechanical Engineering interview questions and answers

Mechanical Engineering Interview questions and answers pdf for freshers and experienced

1. What is your favourite subject in Mechanical engineering?

Ans:   

Normally they are looking for the subject in which their company is based on. Do not worry if you tell other than the subject of company. Be true to yourself. You will be trained once you will be recruited.

2. What was your project during Mechanical engineering?

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They will looking for leadership. If you did project in group work, they will find out your leadership quality by related question.

3. What safety precautions should be observed while working in the workshop ?

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•       Keep shop floor clean, free from oil and other slippery materials.
•       Wear proper dress and avoid loose clothing and loose hair.
•       Wear shoes and avoid chapels.
•       Avoid playing, loose talk and funning inside the shop floor.
•       Keep good housekeeping and put all unnecessary items and rejected items in scrap box.
•       Learn everything about the machine before starting and clear all the doubts.
•       Keep a safe distance from rotating and sliding parts.
•       Never store inflammable materials inside or around the shop.
•       Never play with electricity, fire, parts with sharp edge etc.
•       Keep fire buckets and extinguishers ready for use.

4. What are the precautions to be taken to avoid fire ?

Ans:

•       The buckets along with sand should be placed inside the workshop.
•       Switches and other electrical parts must be made of fireproof material.
•       Carbon dioxide gas should be place at required points in special containers.
•       Fire extinguishers of suitable type should be placed at accessible places.

5. What do you mean by First Aid ?

Ans:

First Aid is immediate and temporary care given to a person who affected accidental injury or a sudden illness before the arrival of doctor.

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16. What is isometric drawing?

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It is a 3-D drawing used by draftsmen, architects etc

17. What is a Process Flow Diagram?

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A Process Flow Diagram (or System Flow Diagram) shows the relationships between the major components in the system. It also has basic information concerning the material balance for the process.

18. Is it the stress that, produces strain or strain produces stress?

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A Force applied to an object will cause a displacement. Strain is effectively a measure of this displacement (change in length divided by original length).

Stress is the Force applied divided by the area it is applied. (E.g. pounds per square inch)

Therefore, to answer the question, the applied force produces both “Stress and Strain”. “Stress and Strain” are linked together by various material properties such as Poisson's ratio and Young's Modulus.

19. What are the points in the stress strain curve for steel?

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Proportional limit, elastic limit or yield point, ultimate stress and stress at failure.

20.State Newton's three laws of Motion.

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• The law of inertia: Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
• Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object). Force=Mass times acceleration.
• For every action there is an equal and opposite reaction.

21.State the laws of thermodynamics?

Ans:

Thermodynamics is a physical science which studies the interrelation between heat, work and the internal energy of any system. Thermodynamics helps study all the systems of mechanical engineering. There are three laws of thermodynamics.

First Law: Energy can be neither created nor destroyed. It can only change forms. In any process in an isolated system, the total energy remains the same.

Second Law: The second law of thermodynamics states that the entropy of any isolated system not in thermal equilibrium almost always increases.

Third Law: As temperature approaches absolute zero, the entropy of a system approaches a minimum.

22.What is Hess law?

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According to the Hess law the energy transfer is simply independent of the way being followed. If the reactant and the product of the whole process are the same then same amount of energy will be dissipated or absorbed.

23.Explain what is torque?

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Torque is the force that causes rotation. It is a measure of how much force is acting on an object making it rotate.

24.What is the difference between torque and power?

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While power determines the speed of a vehicle, torque determines the time in which that speed can be reached. The greater the torque figure, the faster the acceleration. The more torque in the engine, the faster you accelerate. Power is the rate at which work is done, so it is basically the potential of the engine.

25. What is fuel ratio ?

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Fuel ratio is the ratio of its % age of fixed carbon to volatile matter.

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6. What is a Drawing ?

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It is a graphical representation of a real thing to define and specify the shape and size of a particular object by means of lines.

7. What is Engineering Drawing ?

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A drawing which is worked out an engineer for the engineering purpose is known as Engineering Drawing.

8. Explain briefly the following lines used in Engineering drawing ?

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(a)Dimension Lines

Dimension lines are the thin lines used to indicate extents and direction of dimension. These are terminated with arrowheads.

(b)Extension Lines

Extension lines are also thin lines and it used to indicate the termination of a dimension.

(c)Leaders

Leaders are used to direct notes or identification symbols to feature on the drawing.

9. Difference between 'Thermodynamics and Heat Transfer'?

Ans:

Thermodynamics mainly deals with the transfer of energy in form of heat or work between systems and surroundings with other systems in form of either heat or work in equilibrium conditions.  When there is change in one state, which was in equilibrium state and starting to change in other equilibrium state, this information helps to determine heat or work interactions due to this process. While

Heat transfer deals with non equilibrium heat exchange or transfer due to temperature gradient while in thermodynamics, during thermal equilibrium (No temperature gradient) no heat exchange is possible. 

10. Explain in an orderly manner how the force in the member of a truss be detected using the method of joint.

Ans:

The steps required to calculate the force are as follows:

• The reaction at the support has to be first calculated.
• Once the reaction is calculated the direction of force of the member is made to make it tensile. On getting the result to be negative the direction assumed is wrong and this implies the force being compressive in nature.
• A joint needs to be selected whose 2 members are not known. The lami's theorem is used on the joint on which less than three forces are acting.
• After the above process is complete the free body diagrams of the joint needs to be made. Since the system is in equilibrium the condition of Summation of V and H must result in zero.
• After the above step the resolution of forces method needs to be used on the joint on which more than 4 forces are acting.

11. What is mechanism?

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A mechanism is an assembly of different parts which perform a complete motion and is often part of a machine.

12. What is annealing?

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It is a process of heating a material above the re-crystallization temperature and cooling after a specific time interval. This increases the hardness and strength if the material.

13. What is ductile-brittle transition temperature?

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It is the temperature below which the tendency of a material to fracture increases rather than forming. Below this temperature the material loses its ductility. It is also called Nil Ductility Temperature.

14. Difference between tempering and annealing 

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Annealing is a process in which work piece 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.

15. What are the advantages of gear drive?

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Gear drive is useful for power transmission between two shafts, which are near to each other (at most at 1m distance). In addition, it has maximum efficiency while transmitting power. It is durable compare to other such as belts chain drives etc. You can change the power to speed ratio.

Advantages: -

•       It is used to get various speeds in different load conditions.
•       It increases fuel efficiency.
•       Increases engine efficiency.
•       Need less power input when operated manually.

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