# Latest Interview Questions in Mechanical | Mechanical Engineering Interview Questions and Answers | Mechanical Engineer Job Interview Questions | Latest Placement Papers | Mechanical Engg Questions

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.

Originally posted 2011-02-28 17:32:16.

### 33 thoughts on “Latest Interview Questions in Mechanical | Mechanical Engineering Interview Questions and Answers | Mechanical Engineer Job Interview Questions | Latest Placement Papers | Mechanical Engg Questions”

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11. viresh says:

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. viresh says:

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.

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20. indira says:

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…

21. vikasbindra says:

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22. student may ask any question being asked says:

Any question you wana ask related to mechanical engineering ?

23. himanshu says:

difference between pressure and stress

24. parmjeet says:

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26. pratik says:

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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diffrence between distance and isplacement

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