### Constant temperature/ isothermal process

A process, in which the temperature of the working substance remains constant daring its expansion or compression, is called a constant temperature process or isothermal process. This will happen when the working substance remains in a perfect thermal contact with the surroundings, so that the heat 'sucked in' or 'squeezed out' is compensated exactly for the mechanical work done by, or on the gas respectively. It is thus obvious that in an isothermal process:

1. there is no change in temperature, and
2. there is no change in internal energy.

We know that

Q1-2 = dU + W1-2 = W1-2

Hence during isothermal expansion of a gas,

Heat added = Work done by the gas

Similarly, during isothermal compression of a gas,

Heat subtracted = Work done on the gas

A little consideration will show that the isothermal process is governed by Boyle's law. Thus the isothermal equation of a perfect gas is pv = Constant.

Now consider a certain quantity of a perfect gas being expanded isothermally, which is shown by the curve 1-2 in Fig. 5.3.

Let
v1 = Initial volume of gas,
p1 = Initial pressure of gas,
v2 = Final volume of gas, and
p2 = Final pressure of gas.

The workdone during isothermal expansion is given by

W1-2 = Area under the curve 1-2

In general,

where r is the expansion ratio (when gas is heated) or compression ratio (when gas is cooled).

Notes:

(a) Expansion ratio (r) = (Volume at the end of expansion)/(Volume at the beginning of expansion)
(b) Compression ratio (r) = (Volume at the beginning of compression)/(Volume at the end of compression)

### Are Engineers Favourite Among Girls?

What do girls think about men who are engineers and what type of engineers are most favourite among girls? A survey was conducted by a team of aboutmech with members chosen from different countries. Each team member carried out a neutral survey in his/ her country to evaluate what females think about most of the engineers from different engineering branches. An overview of different questions asked in survey is given below:

Question: Which male engineers do you find more attractive as a husband?
Almost 50% women voted for mechanical engineers to be the most attractive husbands among other engineers. So mechanical engineers are most favourite among girls as a husband. They find them more trustworthy, intelligent, and creative. A married women from California said, “If your husband is a mechanical engineer, he will help you in everyday tasks. Because mechanical engineers are good team players and they have creative ideas about everything.”

### Best CV Format for Mechanical Engineers

Fifty percent engineers fail to grab a dream job because of basic faults in their CVs/ Resume. This article tells you about best CV format for mechanical engineers and how you are supposed to design your CV when applying for jobs. You CV is your first impression on future employer. He/ she does not know you. Your CV is the only representation of your personality. He/ she may select or reject you after first glance on your resume.
I have experienced shortlisting and interviewing candidates for different jobs. I was astonished to learn that most of the candidates simply copy paste each others CVs without any changes at all. These types of CVs are rejected immediately. I am not trying to tell you that you should avoid copying, rather i ma telling you to refrain from giving your CV to your friends.
An ideal CV consists of following portions:
Name/ Address of the applicantObjectiveEducation RecordEmployment HistoryProfessional SkillsAwards & AchievementsCo-Curricular Activities/ Inter…

### Engineering Mechanics - Introduction

The Engineering Mechanics is that branch of Engineering-science which deals with the principles of mechanics along with their applications to engineering problems. It is sub-divided into the following two main groups:

(a) Statics, and (b) Dynamics

The Statics is that branch of Engineering Mechanics which deals with the forces and their effects, while acting upon the bodies at rest.

The Dynamics is that branch of Engineering Mechanics which deals with the forces and their effects, while acting upon the bodies in motion. It is further sub-divided into the following two branches:

(i) Kinetics, and (ii) Kinematics

The Kinetics is that branch of Dynamics, which deals with the bodies in motion due to the application of forces.

The Kinematics is that branch of Dynamics which deals with the bodies in motion without taking into account the forces which are responsible for the motion.