# What is Thermodynamics? [A Practical Approach to the Subject]

By | February 5, 2019

## What is Thermodynamics?

The word thermodynamics is derived from Greek words ‘Thermo’ and ‘Dynamics’.

The word ‘Thermo’ means ‘Heat’.

The word ‘Dynamics’ means ‘Force’.

Hence the primitive concept of thermodynamics was to get power (or force) from hot bodies.

This is the scope of thermodynamics which we study in Mechanical Engineering but scope of the subject thermodynamics is much wider.

We can also experience thermodynamics in our day to day life.

We see that hot coffee becomes cold (room temperature) and cold water becomes hot (room temperature).

Also, we observe processes in our daily life which occur spontaneously in only one direction.

For example:

An iron rod which is hot at one end and cold at another end, attains a mean temperature throughout the rod.

Its reverse is not possible, a rod at uniform temperature cannot automatically hot at one end and cold at another end.

From general experience we can see that thermal energy and Mechanical energy are interconvertible.

Also, we see that Mechanical energy can fully be converted into heat energy but conversion of heat energy fully into Mechanical energy is not possible.

We also see that we can reverse some processes which involve transfer of heat but cannot reverse others.

It means that there are certain laws and directional constants associated with these processes (involving transfer of heat) which govern the whole process. We study these laws and directional constants in thermodynamics.

Moreover, the physical properties of a system (e.g. Pressure, Volume and Temperature) which are affected in these processes are also studied in the subject thermodynamics.

## Definition of Thermodynamics

Thermodynamics is a fundamental subject that describes the basis laws governing the occurrence of physical processes associated with the transfer of energy (or transformation of energy) and also it establishes the relationship between different physical properties which have been affected by these processes.

The entire subject thermodynamics is based on the laws of nature formed by our observation and common experience.

If we consider the subject thermodynamics as a building than experimental observations in the laboratory are its base and laws of nature are its pillars.