Skip to main content

Part - 6 Most commonly asked Mechanical Interview Questions with answer

Most commonly asked Mechanical Interview Questions 

 1.          Why Entropy decreases with increase in temperature?

 Ans.      ds=dQ/T Entropy is inversely proportional to the temperature so, as temp. Increases, entropy decreases.

2.           Why different types of sound are produced in different bikes, though they run on SI Engines?

 Ans.       Engine specifications are different in different manufactures like as Bore Diameter (CC), Ignition timing. Also the exhaust passage takes more responsible for sound.

3.           How much Watt means 1Hp?

 Ans.       746.2 Watt

 4.           Explain Bicycle Rear Wheel Sprocket working?

 Ans.      Rear wheel sprocket works under the principle of ratchet and pawl.

5.          Definition of Octane Number and Cetane Number?

 Ans.     Octane No.- Octane number is defined as the percentage, by volume, of iso octane in the mixture of iso octane and h-heptane. It is the measure of rating of SI engine.
Cetane No.- Cetane number is defined as the percentage, by volume, of n-cetane in the mixture of n-cetane and alpha methyl naphthalene. It is the measure of rating of CI engine.

6.         Which Mechanism is used in Automobile gearing System?

 Ans.     Differential mechanism

7.            When Crude Oil is Heated, Which Hydro Carbon comes first?

 Ans.       Natural gas (Gasoline)… at 20 Celsius

8.           How to calculate Bearing number ti Diameter of the inner and outer?

 Ans.      Divide the shaft diameter size by 5, it will give last two digit of the bearing no. and according to type of load we have to choose the type of bearing and that will give prior number of the bearing.

9.           The Fatigue life of a part can be improved by?

 Ans.       Improving the surface finish by Polishing & providing residual stress by Shot peening.

10.          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.

11.          Poisson's Ratio is Higher in, Rubber/Steel/Wood?

 Ans.       When a material is compressed in one direction, it usually tends to expand in the other two directions perpendicular to the direction of compression. This phenomenon is called the Poisson effect. Poisson’s ratio is a measure of the Poisson effect.
For rubber = 0.5
For steel = 0.288
For wood < 0.2

Thus Poisson’s ratio is higher in RUBBER.
See related more FAQs  <<<< Click Here >>>>

Labels:

Popular posts from this blog

Part -5 Most commonly asked Mechanical Interview Questions

Most commonly asked Mechanical Interview Questions with answer 1. Why the Centrifugal Pump is called High Discharge pump? Ans. Centrifugal pump is a kinetic device. The centrifugal pump uses the centrifugal force to push out the fluid. So the liquid entering the pump receives kinetic energy from the rotating impeller. The centrifugal action of the impeller accelerates the liquid to a high velocity, transferring mechanical (rotational) energy to the liquid. So it discharges the liquid in high rate. It is given in the following formulae: Centrifugal force F= (M*V2)/R. Where, M-Mass V-Velocity R-Radius 2. How Cavitation can be eliminated by Pump? Ans. Cavitation means bubbles are forming in the liquid. To avoid Cavitation, we have to increase the Pump size to One or Two Inch To increase the pressure of the Suction Head  Decrease the Pump Speed. 3. Why Cavitation will occur in Centrifugal Pump and not in Displacement Pump? Ans. The form...
Read more

Part -1 Most commonly asked Mechanical Interview Questions with answer

Most commonly asked Mechanical Interview 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 entropy's of the initial, isolated systems is less than or equal to the entropy of the ...
Read more

'NICK' BREAK (BEND) TEST

'NICK' BREAK (BEND) TEST Object :  As for fillet weld fracture, used on butt welds. Method: The specimen is cut transversely to the weld, and a saw cut is applied along the center of the weld face. The best place for the cut is at a start I stop. The specimen is fractured by bending or by hammer blows. The nick bend test will find internal defects. Reporting Results: Thickness of material.  Width of specimen.  Location of fracture.  Appearance of joint after fracture.
Read more