Mechanical Engineering Interview Questions with Answers

During condensation, which type of heat is released
Ans: Latent heat of vaporization

What is a Isochoric process
Ans : Constant Volume (Process that takes place at constant volume)

During sensible cooling of moist air, what happens to its relative humidity
Ans: Increases

At critical point, what is the enthalpy of vaporization is
Ans: Zero 




What is conduction, convection and radiation? Give Examples?
Ans:-
Conduction - The transfer of energy between objects that are in physical contact

Convection - The transfer of energy between an object and its environment, due to circular fluid motion

Radiation - The transfer of energy to or from a body by means of the emission or absorption of electromagnetic radiation

Can you transfer the heat energy from cold body to hot body?
- Yes, with external work. Eg : Air conditioner

What is priming?
Ans:- Pump casing must be filled with liquid before the pump is started, or the pump will not be able to function. If the pump casing becomes filled with vapors or gases, the pump impeller becomes gas-bound and incapable of pumping.

What is yield point?
The yield strength or yield point is the stress at which a material begins to deform plastically.

During rainy season even though thunder occurs first followed by lightning; why do we see lightning first and then hear the thunder?
- Light travels faster than sound

What is viscosity?
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or tensile stress.

What is unit of specific gravity?
A – Dimensionless (No Unit) because it is a ratio of density to density

Zeroth law of thermodynamics:
If two systems are in thermal equilibrium with a third system, then the two systems are also in thermal equilibrium with each other.

What happens to the specific volume of water when heated from 00C
Ans: first decreases and then increases

What is the meaning of Entropy
Entropy may be understood as a measure of disorder within a macroscopic system.

The second law of thermodynamics states that an isolated system's entropy never decreases. Such systems spontaneously evolve owards thermodynamic equilibrium, the state with maximum entropy.

What is a Steady state process:
Ans:  A process that occurs without a change in the internal energy

What is a specific heat?
The specific heat is the amount of heat required per unit mass to raise the temperature by one degree Celsius.


Name 3 units of Energy
Joules, Kilo Watt Hour, British Thermal Unit (BTU), Calories, Tons of Oil Equivalent, Electron Volt, Foot-Pound

Name some forms of Energy
Kinetic, Potential, Mechanical, Electric, Magnetic, Gravitational, Chemical, Ionization, Nuclear, Chromodynamics, Elastic, Mechanical wave, Sound wave, Radiant, Thermal

What is the difference between complete and incomplete combustion
Ans:- Incomplete combustion occurs due to insufficient oxygen. In complete combustion, carbon dioxide is the only product that includes carbon whereas, in incomplete combustion, carbon monoxide and carbon dust are formed as products.

What are the products of a complete combustion?
During complete combustion carbon and hydrogen combine with oxygen (O2) toproduce carbon dioxide (CO2) and water (H2O). During incomplete combustion part of the carbon is not completely oxidized producing soot or carbon monoxide(CO).

What is the difference between Absorption and Adsorption
Absorption is the process in which a fluid is dissolved by a liquid or a solid (absorbent). Adsorption is the process in which atoms, ions or molecules from a substance (it could be gas, liquid or dissolved solid) adhere to a surface of the adsorbent.

What is a Catalyst:-
a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.

What is a Reynolds Number
The Reynolds number is a dimensionless value that measures the ratio of inertial forces to viscous forces and descibes the degree of laminar or turbulent flow.

What is In Bernoulli's principle in fluid dynamics
Bernoulli's principle states that an increase in the speed of a fluid occurs siimultaneously with a decrease in pressure or a decrease in the fluid's potential energy

What is sublimation
A process change in which a substance changes from a solid to a gas without ever passing through a liquid phase.

What is heat capacity
The heat capacity of a substance indicates the ease with which a substance heats up. A good thermal conductor would have a low heat capacity, indicating that a small amount of energy causes a large temperature change. A good thermal insulator would have a large heat capacity, indicating that much energy transfer is needed for a temperature change.

What is Mechanical Equilibrium
Mechanical equilibrium: when there is no change in pressure at any point of the system. However, the pressure may vary within the system due to gravitational effects.

What is Thermal Equilibrium
Thermal equilibrium: when the temperature is the same throughout the entire system.

What are intensive properties of a system with respect to Thermodynamics.
Intensive properties: are those that are independent of the size (mass) of a system, such as temperature, pressure, and density. They are not additive.

The kinematic viscosity is the ratio of
absolute viscosity to the density of the liquid



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