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Latest Interview Questions in Mechanical Engineering With Answers (Freshers And Experienced)

The following are some of the most frequently asked latest interview questions in mechanical engineering. For any job, there is a chance that you might get interviewed by someone over the phone or through an e-mail. Here are some of the common questions.

Latest Interview Questions In Mechanical Engineering

This blog is a compilation of 1000+ questions to polish up your Mechanical Engineering Interview skills. There are multiple choices of questions for you to select the best option. The technical questions and answers in this article will give you a clear picture of what to expect in a real life scenario.

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What is the importance of thermodynamics in the field of mechanical engineering? | Latest Interview Questions in Mechanical Engineering

All mechanical engineering systems are studied with the help of thermodynamics. Hence it is very important for mechanical engineers.

How many Laws of Thermodynamics are there?  | Latest Interview Questions in 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: 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.

State the Laws of conservation of energy?  | Latest Interview Questions in Mechanical Engineering

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.”

Is the boiler a closed system? | Latest Interview Questions in Mechanical Engineering

Yes, definitely the boiler is a closed system.

What is the Carnot engine?  | Latest Interview Questions in Mechanical Engineering

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.

Which formula forms a link between the Thermodynamics and Electro chemistry? | Latest Interview Questions in Mechanical Engineering

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)

Which is the hardest compound known? | Latest Interview Questions in Mechanical Engineering


What is Hess Law? | Latest Interview Questions in Mechanical Engineering

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.

Which has more efficiency: Diesel engine or Petrol engines? | Latest Interview Questions in Mechanical Engineering

Of course, the Diesel engine has the better efficiency out of the two.

In what ways are thermodynamics and heat transfer distinct from one another?  | Latest Interview Questions in Mechanical Engineering

The terms Thermodynamics and Heat Transfer are both used in the field of thermal engineering, and each has its own significance and meaning. Given that both topics deal with heat and energy, one may wonder what the actual distinction is between the two subjects is. Thermodynamics and Heat Transfer, to give them their full titles.

“Thermodynamics” is concerned with the quantity of energy released in the form of heat or work throughout a process, and it only takes into account the end states that are in equilibrium with the process. However, it will not provide any indication as to how long it will take to achieve the ultimate equilibrium condition. While,

“Heat Transfer” is concerned with the pace of energy transfer, and as a result, it provides an indication of how long a heat transfer will last. Heat transfer is concerned with time-dependent and non-equilibrium processes. Only when there is a temperature differential in a body, which indicates the presence of non-equilibrium processes, can heat be transferred.

In summary, when there is a problem regarding the transmission of heat, thermodynamics will tell you “Why” a process will occur, and heat transfer will tell you “how” a process will occur.

When it comes to thermodynamics, the distance traveled from (1) and (2) is referred to as the state point in thermodynamics.

However, heat transfer describes how to travel via bus, flight, or train, i.e., either by conduction, convection, or radiation or by a mixture of these in many possible variations, as opposed to mass transfer.

Thermodynamics uses the principles of thermodynamics to support all of these claims.

The Zeroth Law of Thermodynamics, First Law of Thermodynamics, second law, and third law of Thermodynamics, Heat Transfer, on the other hand, makes use of

  • Fourier’s Theorem (Heat conduction)
  • Law of Cooling (Newton’s Law of Cooling) (Heat convection)
  • Planck’s Law (Thermal Radiation)
  • The Law of Stephan Boltzman (Thermal Radiation)
  • Wein’s Law (Thermal Radiation)
  • Kirchoff’s Law (Thermal Radiation)
  • Lambart’s Law (Thermal Radiation)

In thermodynamics, what exactly is entropy? | Latest Interview Questions in Mechanical Engineering

Converting energy from one form to another results in some energy loss. For example, carrying electric current via wires adds resistance, which loses energy, and operating an inefficient engine on fossil fuels results in energy loss as well. Considering that none of these processes is 100 percent efficient, they all produce energy losses in the form of heat. As a result, the amount of heat in our environment is always rising; this is known as the entropy of our system.

Entropy is defined as energy that has lost its ability to do work. In thermodynamics, it is steam that has reached the end of its pressure and useable energy, but is still a gas and must be condensed into water, losing the energy associated with the transition of state. It then consumes energy to heat itself before changing back into steam under pressure, which may then be utilized as energy.

Please keep in mind that this amount may only grow or remain constant (i.e., constant when everything is running at 100 percent efficiency).

Why does thermodynamics treat ambient air as a pure substance? | Latest Interview Questions in Mechanical Engineering

The fact that the chemical composition of atmospheric air remains constant and homogenous across the whole atmosphere leads to its classification as a pure material. Water, on the other hand, is regarded to be a pure material. The term “pure” refers to anything that has maintained its chemical makeup throughout time and is thus regarded to be pure.

In thermodynamics, we discover the refrigerator’s COP, not its efficiency. Why? | Latest Interview Questions in Mechanical Engineering

Energy converters and energy transferring devices are the two types of gadgets that are available. In contrast to energy conversion devices, the efficiency of a heat (energy) transferring device is measured by the coefficient of performance (COP) of the device (steam turbines). COP is sometimes referred to as the ratio of Energy Output to Energy Input, which is the same as energy efficiency.

Energy converters provide output that is a fraction of the energy input, and in certain cases, the output is even less than the energy intake. As a result, the rules of thermodynamics dictate that the efficiency will be less than 100 percent in this case.

The quantity of heat taken from a heat source is referred to as the energy output of an energy transfer device (ETD) (space to be cooled-in case of refrigeration). The energy that has been taken is not a fraction of the energy that has been supplied. The amount of energy that can be retrieved may be greater than the amount of energy that can be input. The efficiency of an energy-transferring device may thus be more than 100 percent without breaking the first rule of thermodynamics, which is a significant achievement. As a result, the term “coefficient of performance” was coined.

Both efficiency and coefficient of performance (COP) are attempting to provide you with the performance value of the system, whether it is a refrigerator or an engine, where input and output energies are involved.

However, the distinction is in the kinds of energy that are involved. There are two kinds of energy, namely, High-Grade Energy and Low-Grade Energy, which are distinguished by their quality.

As a measure of efficiency, the ratios should be between (1-(heat out/heat input)), the same type of energy, and 1. That is heat, which is a low-grade form of energy. As a result, it will never be more than 1.

The COP, on the other hand, is concerned with the relationship between (heat removed/electricity supplied). Both are various types of calculations. Electricity is a high-quality source of energy. So the COP is higher than one.


The industrial revolution is a period of time when machines replaced men. In this article, we talk about the latest interview questions in mechanical engineering. If you are looking for a job as a mechanical engineer, then you should know the answers to these questions, otherwise, you might lose your chance of getting selected.

34 thoughts on “Latest Interview Questions in Mechanical Engineering With Answers (Freshers And Experienced)”

  1. attention plz……. no cycle can be 100% efficient. if it happens then it is clearly the violation of the thermodynamics 2nd law ( kelvin plank statement), as this law states” it is impossible to construct a device which while working in a cyclic manner would convert the heat into work completely without rejecting any amount of the heat to the sink.” 100% efficiency means that all the heat input is converted into work without any rejection of heat. it is a case of PMM2.
    this can also be understood in the way that efficiency of carnot cycle is given by the formula= 1-T2/T1, where T2= temperature of source, T1= temp of sink.

    1. carnot engine is the idealization of an engine and is completely reversible engine which have the higher efficiency than any other irreversible engine. also according to carnot theorem all the reversible engine have the same efficiency.

  2. hello viresh your right all te revesible engines has same efficiency…but clause is ter they must operate at same temperature…and carnot engine is the hypothetical engine with which we used to compare remaining engines…

  3. Diamond is no more Hardest one. Wurtzite boron nitride, 18% stronger than diamond and lonsdaleite, a whopping 58% tougher (Hexagonal Diamond)

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