# Mechanical Interview Questions and Answers | Job Interview Questions & Answers | Free Sample Interview Questions | Tough Interview Questions | General Interview |

## Mechanical Interview Questions:

Following mechanical interview questions are frequently asked in the interview panels for both fresher’s as well as an experience candidate in mechanical engineering field.

## Explain the Second Law of Thermodynamics?

The entropy of the universe increases over time and moves towards a maximum value.

The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time, and is constant if and only if all processes are reversible. Isolated systems spontaneously evolve towards thermodynamic equilibrium, the state with maximum entropy.

## How do you measure temperature with a Wet Bulb Thermometer?

As an example, Wet bulb temperature is measured with a wet bulb thermometer. Here, the bulb covering with a wick and wetting it with water. However, wet bulb temperature corresponds to the dew point temperature and relative humidity.

## Which of the following is more close to a black body?

1. Blackboard paint
2. Green leaves
3. Black holes
4. Red holes

1. Black board paint

### What is Bending moment?

When a bending moment is applied to bend an element, as a rule bending moment exists in the element

## What are the salient points in the Stress Strain curve for Steel?

In summary, the stress – strain curve salient features are Proportional limit, elastic limit or yield point, ultimate stress and stress at failure.

## Define Reynolds number?

The Reynolds number is the ratio of inertial force and viscous forces. It is a dimensionless number. By the way it determines the type of fluid flow.

## What is a Newtonian fluid?

A Newtonian fluid possesses a linear stress – strain relationship curve and it passes through the origin. The fluid properties of a Newtonian fluid do not change when any force acts upon it.

## How many Joules is 1 BTU?

1 BTU is equal to 1055.056 joules.

## What is PS?

PS is Pferdestarke, the German unit for Horsepower.

## Explain Otto cycle?

Otto cycle can be explained by a pressure volume relationship diagram. However, It shows the functioning cycle of a four stroke engine. Most importantly, the cycle starts with an intake stroke, closing the intake and moving to the compression stroke, starting of combustion, power stroke, heat exchange stroke where heat is rejected and the exhaust stroke. Meanwhile, it was designed by Nicolas Otto, a German engineer.

## By higher octane number of Spark ignition, fuel, it means that the fuel hose?

1. Higher heating value
2. Higher flash point
3. Lower volatility
4. Longer ignition delay

## Explain the nomenclature of a 6203-ZZ bearing?

For instance, 6 is the type code, which shows it is a single-row ball bearing, certainly 2 is the series, means light, after that, 03 is the bore, which is 17 mm and finally, ZZ is the suffix meaning double shielded bearing.

## What is a Gear ratio?

The gear ratio is the ratio of the number of revolutions of the pinion gear to one revolution of the idler gear.

## What is Annealing?

Annealing is a process of heating a material above the re-crystallization temperature and consequently cooling after a specific time interval. Therefore, this increases the hardness and strength of the material.

## Define Torque?

Torque is defined as a force applied to an object subsequently results in rotational motion.

## What is Ductile-Brittle Transition Temperature?

It is the temperature below which the tendency of a material to fracture increases rather than forming. Most importantly below this temperature the material loses its ductility. It is also called Nil Ductility Temperature.