What is the First Law of Thermodynamics?

Human beings tend to consider themselves as the creators of the world, and why not? They have been responsible for the development of the world that it is today. See the huge infrastructures in the form of tall buildings, long bridges, posh hotels, showrooms and what-not. If you are still not convinced look at the advanced vehicles like cars, trucks, airplanes and ships created by the humans and used by us in our day-to-day lives. Then consider the complicated electrical and communications systems developed by we humans. But before we develop an ego for what we have created in this world don’t forget the contributions of nature.

For the most basic needs the human beings are still entirely dependent of nature. We just cannot live without water and air. Can we produce them? Maybe yes, but not for the entire population of the world. The next important need for which we depend entirely or rather desperately on nature is energy. The man who takes pride for creating the present world, would he/she have been able to do this without energy? Man has only learnt utilizing or exploiting the resources of the nature for their comfort and then forgotten that they have been able to create only because of the gifts of nature.

For decades we have been using energy blindly as if it has been manufactured by our forefathers, and in turn we will be manufacturing it for our coming generations. As I said we have learnt only to use energy in various forms like electrical, mechanical, heat etc. We have also learnt to convert the energy from one form to the other as you must have noticed in the vehicles where chemical energy is converted into mechanical energy, in thermal power plants where chemical energy is converted into electrical energy, in electrical motors where electrical energy is converted into mechanical energy.

This is what the mankind can do: convert the energy from one form to the other form and utilize it as per their needs and convenience. We just cannot create energy. Have you ever heard of scientists creating fossil fuels on such a large scale? Can we produce oil in oil wells? Can we create huge rivers to generate hydro power? Can we create even the tiny nucleus of the atom? Can we create winds to generate wind energy? Can we create another sun that keeps on emitting solar energy continuously? The answer to all these questions is no. Einstein has taught us how much energy can be obtained from a mass of chemical, but even his conclusions tell us that human beings cannot create energy, they can only use it and convert it.

This brings us to the first law of thermodynamics. It is very simple and simply says that energy can neither be created nor it can be destroyed, however, it can be converted from one form to the other.

We humans beings are also well known for destruction, so how is it that we cannot destroy energy? Well, we can only waste energy, nature’s as well as ours own, but cannot destroy energy. Let us consider boiling water. If you persist with heating it for long time, water will get converted into steam. In this case the person may feel that heat energy obtained from the LPG fuel has been destroyed, but in actual sense the heated steam mixes into atmosphere increasing its energy content, which is also called entropy.

There are four important basic laws of thermodynamics: first law, second law, third law, and Zeroth’s law. First thought of by Sadi Carnot, these are the base of study in the thermodynamics field. Thermodynamics is very important subject area for mechanical engineering. A number of modern inventions are based on the applications of various laws of thermodynamics.