Mechanical Engineering Interview question

1. What is the importance of the Thermodynamics in the field of Mechanical Engineering?
All the mechanical engineering systems are studied with the help of thermodynamics. Hence it is very important for the mechanical engineers.

2. How many Laws of Thermodynamics are there?
There are three laws of the 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: When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium in itself, but not in equilibrium with each other at first, are at some time allowed to interact, breaking the isolation that separates the two systems, and they exchange matter or energy, they will eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated systems is less than or equal to the entropy of the final exchanging systems. In the process of reaching a new thermodynamic equilibrium, entropy has increased, or at least has not decreased.

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

3. State Laws of conservation of energy?
According to the laws of conservation of energy, “energy can neither be created nor be destroyed. It can only be transformed from one form to another.”

4. Is the boiler a closed system?
Yes definitely the boiler is a closed system.

5. What is Carnot engine?
It was being designed by Carnot and let me tell you that Carnot engine is an imaginary engine which follows the Carnot cycle and provides 100% efficiency.

6. Which formula forms a link between the Thermodynamics and Electro chemistry?
Gibbs Helmholtz formula is the formula which forms the link between the thermodynamics and electromagnetism.

∆Hs/R = [∂ lnp /∂ (1/T)]x

where: x – mole fraction of CO2 in the liquid phase
p – CO2 partial pressure (kPa)
T – temperature (K)
R – universal gas constant
α – mole ratio in the liquid phase (mole CO2 per mole of amine)

7. Which is the hardest compound known?
Diamond.

8. What is Hess Law?
According to the Hess law the energy transfer is simply independent of the path 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.

9. Which has more efficiency: Diesel engine or Petrol engines?
Off course Diesel engine has the better efficiency out of two.

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Job Recruitment Questions on basic Computer Technology and Internet Part-1

Click Here for  Job Recruitment Questions on basic Computer Technology and Internet Part-1. 

Question:  Which one is the computer’s own language?

Answer:     Low level language which is written in binary

Question: What is the meaning of URL?

Answer:   Uniform resource locator.

Question: When Microprocessor was invented?

Answer:    In 1971

Question: What is UNIX?

Answer:   Operating System

Question: What is the meaning of Fat?

Answer:    File allocation table

Question: What is Adobe Photoshop?

Answer :   Photo Editing Software.

Question: What is Windows?

Answer :  Operating System by Microsoft

Question: What is Laptop?

Answer : Small portable computer

Question:Who invented punch card?

Answer:  Joseph Marie Jacquard

Question: What is SIMM?

Answer:   Single Inline Memory Module

Question: What is the short name of binary math?

Answer:    bit

Question: What is ROM?

Answer:    Read Only Memory.

Question: What is RAM?

Answer:    RAM= Random Access Memory

Question: Which is the  first computer in Bangladesh?

Answer:  IBM-1620 series

Question: Where the computer museum is situated?

Answer:    in USA

Question:  What does BIOS  means?

Answer:    Basic Input Output System

Question:  Which one is the brain of computer?

Answer:    Micro Processor

Question: Who is the father of modern computer?

Answer:   Charles Babbage

Question:  What is the name of first personal computer?

Answer:    Sphere 1 (according to WikiPedia)

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About Technical interview - Introduction

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basic interview questions

op 10 Interview Questions and Best Answers

Review the top 10 interview questions you'll most likely be asked at a job interview, plus the best answers. Also, review the other questions you may be asked, so you're prepared to ace the interview.

1. What is your greatest strength? - Best Answers
This is one of the questions that employers almost always ask. When you are asked about your greatest strengths, it's important to discuss the attributes that will qualify you for the specific job and set you apart from the other candidates.

2. What is your greatest weakness? - Best Answers
Another typical question interviewers will ask is about your weaknesses. Do your best to frame your answers around positive aspects of your skills and abilities as an employee.

3. Tell me about yourself. - Best Answers
Here’s how to answer questions about you without giving out too much – or too little – personal information.

Start by sharing some of your personal interests which don't relate directly to work.

4. Why should we hire you? - Best Answers
Are you the best candidate for the job? Be prepared to say why.  Make your response a concise sales pitch that explains what you have to offer the employer, and why you should get the job.

5. What are your salary expectations? - Best Answers
What are you looking for in terms of salary? It seems like a simple question, but your answer can knock you out of content for the job if you overprice yourself. Here's the best way to answer questions about salary.

6. Why are you leaving or have left your job? - Best Answers
When asked about why you are moving on, stick with the facts, be direct and focus your interview answer on the future, especially if your leaving wasn't under the best of circumstances.

7. Why do you want this job? - Best Answers
This question gives you an opportunity to show the interviewer what you know about the job and the company. Be specific about what makes you a good fit for this role, and mention aspects of the company and position that appeal to you.

8. How do you handle stress and pressure? - Best Answers
What do you do when things don’t go smoothly at work? The best way to respond to this question is to give an example of how you have handled stress in a previous job.

9. Describe a difficult work situation / project and how you overcame it. - Best Answers
The interviewer wants to know what you do when you face a difficult decision. As with the question about stress, be prepared to share an example of what you did in a tough situation.

10. What are your goals for the future? - Best Answers
This question is designed to find out if you’re going to stick around or move on as soon as you find a better opportunity. Keep your answer focused on the job and the company you’re interviewing with.

11.Why did you quit your job?

Do You Have Any Questions?

At the close of the interview, most interviewers ask whether you have any questions about the job or company. It's always a good idea to have a list ready and to be prepared to respond.

Mechanical Engineering interview questions and answers

Mechanical Engineering interview questions and answers Part 1   Part 2   Part 3   Part 4   Part 5   Part 6 1.What are the different types of fits? Explain? 2. What are the factors that can affect the Factor of safety selection? 3. What is heat treatment and why is it done? 4. What are the rules that must be kept in mind while designing castings? 5. What are the points that should be kept in mind during forging design? 6. Describe briefly the different cold drawing processes. 7. What are the different theories of failure under static load, explain briefly? What are the different types of fits? Explain? On the basis of Indian standards fits can mainly be categorized into three groups: > Clearance Fit: These types of fits are characterized by the occurrence of a clearance between the two mating parts. The difference between the minimum size of the hole and the maximum size of the shaft is called the minimum clearance, the difference between the maximum size of the hole and the minimum size of the shaft is known as maximum clearance. > Interference Fit: In these types of fits the size of the mating parts are predefined so that interference between them always occurs. The tolerance zone of the hole is completely below the tolerance zone of the shaft. > Transition Fit: As the name suggests these type of fit has its mating parts sized limited to allow either clearance or interference. The tolerance zone of the hole and the shaft overlaps in case of such fits. For a shaft designated as 40 H8/f7, calculate the tolerances. Given: Shaft designation = 40 H8/f7 The shaft designation 40 H8/f 7 means that the basic size is 40 mm and the tolerance grade for the hole is 8 ( i. e. I T 8) and for the shaft is 7 ( i. e. I T 7). Since 40 mm lies in the diameter steps of 30 to 50 mm, therefore the geometric mean diameter, D = Square root of (30 x 50) = 38.73 mm We know that standard tolerance unit, i = 0.45 x Cube root of (D) + 0.001 D i = 0.45 × 3.38 + 0.03873 = 1.559 73 or 1.56 microns i = 1.56 × 0.001 = 0.001 56 mm ...(1 micron = 0.001 mm) The standard tolerance for the hole of grade 8 (IT8) = 25 i = 25 × 0.001 56 = 0.039 mm The standard tolerance for the shaft of grade 7 (IT7) = 16 i = 16 × 0.001 56 = 0.025 mm What are the factors that can affect the Factor of safety selection? The factor of safety is used in designing a machine component. Prior to selecting the correct factor of safety certain points must be taken into consideration such as: > The properties of the material used for the machine and the changes in its intrinsic properties over the time period of service. > The accuracy and authenticity of test results to the actual machine parts. > The applied load reliability. > The limit of stresses (localized). > The loss of property and life in case of failures. > The limit of initial stresses at the time period of manufacture. > The extent to which the assumptions can be simplified. The factor of safety also depends on numerous other considerations such as the material, the method of manufacturing , the various types of stress, the part shapes etc. What is heat treatment and why is it done? Heat treatment can be defined as a combination of processes or operations in which the heating and cooling of a metal or alloy is done in order to obtain desirable characteristics without changing the compositions. Some of the motives or purpose of heat treatment are as follows: > In order to improve the hardness of metals. > For the softening of the metal. > In order to improve the machinability of the metal. > To change the grain size. > To provide better resistance to heat, corrosion, wear etc. Heat treatment is generally performed in the following ways: > Normalizing > Annealing > Spheroidising > Hardening > Tempering > Surface or case hardening What are the rules that must be kept in mind while designing castings? Some of the points that must be kept in mind during the process of cast designing are as follows: > To avoid the concentration of stresses sharp corners and frequent use of fillets should be avoided. > Section thicknesses should be uniform as much as possible. For variations it must be done gradually. > Abrupt changes in the thickness should be avoided at all costs. > Simplicity is the key, the casting should be designed as simple as possible. > It is difficult to create true large spaces and henceforth large flat surfaces must be avoided. > Webs and ribs used for stiffening in castings should as minimal as possible. > Curved shapes can be used in order to improve the stress handling of the cast. What are the points that should be kept in mind during forging design? Some of the points that should be followed while forging design are: > A radial flow of grains or fibers must be achieved in the forged components. > The forged items such as drop and press forgings should have a parting line that should divide the forging into two equal halves. > The ribs in a forging should not be high or thin. > In order to avoid increased die wear the pockets and recesses in forgings should be minimum. > In forgings the parting line of it should lie as far as possible in a single plane. > For ease of forging and easy removal of forgings the surfaces of the metal should contain sufficient drafts. Describe briefly the different cold drawing processes. Some of the important cold drawing processes are as follows: > Bar and Rod Drawing: In the case of bar drawing the hot drawn bars are at first pickled, washed and coated to prevent oxidation. Once this is done a draw bench is used for the process of cold drawing. In order to make an end possible to enter a drawing die the diameter of the rod is reduced by the swaging operation. This end is fastened by chains to the draw bench and the end is gripped by the jaws of the carriage. In this method a high surface finish and accuracy dimensionally is obtained. The products of this process can be used directly without any further machining. > Wire Drawing: Similar to the above process the bars are first pickled, washed and coated to prevent any oxidation. After this the rods are passed through several dies of decreasing diameter to provide a desired reduction in the size ( diameter ). The dies used for the reduction process is generally made up of carbide materials. >Tube Drawing: This type of drawing is very similar to the bar drawing process and in majority of cases it is accomplished by the use of a draw bench. What are the different theories of failure under static load, explain briefly? The main theories of failure of a member subjected to bi-axial stress are as follows: > Maximum principal stress theory ( Rankine’s theory): This theory states that failure occurs at a point in member where the maximum principal or normal stress in a bi-axial system reaches the maximum strength in a simple tension test. > Maximum shear stress theory ( Guest’s or Tresca’s theory): This theory states that failure occurs when the biaxial stress reaches a value equal to the shear stress at yield point in a simple tension test. > Maximum principal strain theory ( Saint Venant theory): This theory states that failure occurs when bi-axial stress reaches the limiting value of strain. > Maximum strain energy theory ( Haigh’s theory): This theory states that failure occurs when strain energy per unit volume of the stress system reaches the limiting strain energy point. > Maximum distortion energy theory ( Hencky and Von Mises theory): This theory states that failure occurs when strain energy per unit volume reaches the limiting distortion energy.

Electrical Interview Questions with Answers

[Q] How does the Induction motor work? (OR) Why does the Rotor rotate?

• When the 3 phase stator windings are fed by 3 phase supply, a magnetic flux of constant magnitude which is rotating at synchronous speed is set up. 
• The flux passes through the air-gap and sweeps past the rotor surface  thus it cuts the rotor conductors. 
• Due to the relative speed between the rotating flux and the stationary rotor conductors, an emf is induced in the stationary rotor conductors as per the Faraday's laws of electromagnetic induction.
• The frequency of the induced emf is the same as the supply frequency.
• Its magnitude is proportional to the relative velocity between the flux and the conductors.
• Its direction will be as per Fleming's right hand rule.
• Since the rotor conductors form a closed circuit the rotor current is produced.
• This current's direction will oppose the very cause producing it ( as per Len's law)
• Here the cause is the relative velocity between the rotating flux of the stator and the stationary rotor conductors.
• Hence, in order to reduce the relative speed, the rotor begins to rotate in the same direction as that of the rotating magnetic flux and tries to catch up with the rotating flux. Thus the rotor of induction motor starts to rotate.

[Q] What is the general working principle of Induction motor?

• The conversion of electrical power into mechanical power takes place in the rotating part of an electric motor. 
• In DC motors the electrical power is conducted directly to the armature through brushes and commutator. 
• Thus the DC motor can be called as conduction motor. But in case of AC motors, the rotor receives electric power, not by conduction but by induction. 
• This is exactly in the same way as the secondary of two winding transformer receives its power from the primary. 
• That is why such motors are known as induction motors. 
• Thus an induction motor is also known as rotating transformer ( ie, one in which primary winding is stationary and the secondary is free to rotate)

[Q] What is the advantage of skewed stator slots in the rotor of Induction motors?

In the induction motor design, the rotor slots are purposely made with a slight skew arrangement. It will not be parallel to the shaft. 

This is for the purpose of reducing magnetic locking or reducing magnetic attraction between stator and rotor teeth. 

In addition to that this arrangement will help to reduce the magnetic hum and noise.

[Q] What is meant by cogging in the Induction motor? How to prevent the cogging?

When the number of teeth in stator and rotor are equal, the stator and rotor teeth have a tendency to align themselves exactly opposite to each other, since this corresponds to minimum reluctance position. In such case the rotor may refuse to accelerate. This phenomenon is called as magnetic locking or cogging. 

This problem can be prevented by proper choice of stator and rotor slots and also by skewing the rotor slots by one slot pitch.

[Q] What are the various methods of measuring slip?

1. By actual measurement of rotor speed

2. By measurement of rotor frequency

3. Stroboscopic method

[Q] What are the various methods of speed control in three phase induction motors?

(i) Control from stator side

1. By changing the supply frequency

2. By changing the number of stator poles

3. By changing the supply voltage

(ii) Control from rotor side

1. By inserting resistance in rotor circuit

2. By various ways of cascade connection

3. By injecting EMFs in the rotor circuit.

[Q] What is meant by crawing in the induction motor?

In induction motors, particularly squirrel cage type induction motors, sometimes exhibit a tendency to run stably at speeds as low as one-seventh of their synchronous speed Ns. This phenomenon is known as crawling of an induction motor and the speed is called as crawling speed

Advice on Writing a Job Offer Acceptance Letter

Example of a Letter Accepting a Job Offer - Hard Copy 

Jane Fieldstone
87 Washington Street
Smithfield, CA 08055
(909) 555-5555
jane.fieldstone@gmail.com

Date

Dear Ms. Fieldstone,

As we discussed on the phone, I am very pleased to accept the position of Advertising Assistant with Smithfield Granite and Stonework. Thank you again for the opportunity. I am eager to make a positive contribution to the company and to work with everyone on the Smithfield team.

As we discussed, my starting salary will be $38,000 and health and life insurance benefits will be provided after 30 days of employment.

I look forward to starting employment on July 1, 20XX. If there is any additional information or paperwork you need prior to then, please let me know.

Again, thank you very much.

Signature 

Jane Fieldstone

Example of a Letter Accepting a Job Offer - Email

Subject line: Jason Burnett - Job Offer Acceptance 

Dear Jarod, 

It was wonderful to speak with you on the phone yesterday about the Marketing Director role at ABC Company. I'm thrilled to formally accept this job offer. I'm looking forward to working with you, and the rest of the senior management team at ABC, on charting a new direction for marketing strategy. 

As we discussed, my start date with be May 13, 20XX, with an annual salary of $65,000, and three weeks of paid time off. This salary does not include health insurance, effective on my start date. 

I'm looking forward to seeing you next Monday. Please let me know if there is any paperwork or additional information you need from me beforehand, or if there is any documentation I should bring along on my first day.

I'm always available on email, but feel free to call if that's more convenient (555-555-5555). 

Again, thank you so much for this opportunity. 

Best, 

Jason 

Kính gửi Công ty XXX

Tôi rất vui mừng khi nhận được thư mời nhận việc từ phía phòng tuyển dụng. Vị trí [.xxx..] chính là công việc đúng chuyên môn tôi thực sự muốn gắn bó và phát triển lâu dài, nhất là trong môi trường làm việc của Quý công ty.

Chính vì vậy, tôi viết thư này để xác nhận: đảm nhận vị trí công tác trên, và tôi sẽ cố gắng hoàn thành tốt nhất công việc có thể. Tuy nhiên, về chính sách hỗ trợ làm thêm giờ, tôi có 1 số vấn đề thắc mắc như sau:…..Rất mong nhận được hồi đáp từ phía Quý công ty!

Về thời gian bắt đầu công việc: Tôi có thể nhận việc từ ngày […].

Tôi xin chân thành cảm ơn!

Mọi chi tiết xin liên hệ:…..”