Why are the three Laws of Thermodynamics so important?

    Our concept of "Modern Science" is based on a series of major discoveries that define our understanding of the universe. The Laws of Thermodynamics are important because they control interactions of everything in the universe - regardless of scale. These rules stretch across every form of science known to humankind.

    To understand the same lets see the Classical physics, so, from a certain perspective, it is entirely based on Newton's Laws of motion. Most of the equations and principles taught in physics are based on these simply stated rules. In a similar way, thermodynamics is defined and based on the fundamental principles known as the Laws of Thermodynamics. All of the equations and guidelines used to design engines, analyze machines, and understand natural phenomena are subject to these laws.

The Laws of Thermodynamics take on a special importance because of their scope:-

    It has been shown that Newton's laws of physics are only applicable in certain conditions. These conditions include pretty much every situation important to most engineers, chemists, and scientists. However, there are some known conditions where "Newtonian" physics are inaccurate. The Laws of Thermodynamics have no such exceptions. Energy is conserved, regardless of the amount or type of energy. Closed systems always tend towards greater entropy unless externally modified, whether those systems are atomic or galactic in size.

    This means that the three Laws of Thermodynamics have influence over every scientific discipline, every biological or geological process, and every interstellar system.

     We can immediately test certain ideas against the Laws of Thermodynamics to see if they follow some of the universe's most basic rules. Ideas that don't follow those rules are either wrong or must be caused by some supernatural influence. For example, perpetual motion machines are provably impossible according to the Laws of Thermodynamics. The first law shows that energy (or matter) cannot be created from nothing, and the second law shows that a closed system will degrade its own energy over time. A machine that runs forever without any external energy source is either fictional or powered by some unnatural source.

     The significance of the zeroth law of thermodynamics

    The zeroth law is required in order to define the idea of “temperature” as a property of systems in thermodynamic equilibrium (as well as indirectly define/require the property of thermodynamic equilibrium in an isolated system in the first place). It is the basis for the construction of thermometers, which we need in order to make thermodynamics a quantitative science in the first place. 

Why the Second law of thermodynamics is very important?

    Well if the 2nd Law (and the other Laws) of Thermodynamics didn’t exist then nor would we. Without the 2nd Law the universe would become unstable and fail cataclysmically - if it ever managed to get started in the first place. Energy is needed in every process - so how it behaves and what rules it follows are critically important.

    Second law of thermodynamics is very important because it talks about entropy. Entropy dictates whether or not a process or a reaction is going to be spontaneous’.

I want you to realize that any natural process happening around you is driven by entropy!!

Let’s take a daily life example:

We drink coffee every day. What happens to our cup of hot coffee in say 10 minutes? The coffee starts getting cold, or in thermodynamic terms you will tell me that the hot coffee gives out heat to the surroundings and in turn the coffee cools down. You are 100% correct, but the thing you might not have realized is that this very obvious daily life phenomenon is governed by “entropy”.

What is the Significance of the First Law of Thermodynamics

                    

It establishes the relation between heat and work. The total energy of an isolated system must remain constant.

• According to this law, a fixed amount of heat is needed to get a fixed amount of work or to get a fixed amount of heat a fixed amount of work is needed.

• It is impossible to get work or energy without expending something.

• Work and heat are equivalent to each other.

• It is nothing but the principle of conservation of energy. In any system, the sum of work done and change in internal energy is always equal to supplied heat.

• If the system gains or loses energy then exactly the equivalent amount of energy of the surrounding will have a loss or gain.

• No engine has been built which is able to perform work without expending fuel or energy, i.e., it is not possible to invent the perpetual motion machine which can perform work without expending energy.

You cannot have a device which gives output as work without any heat input. This device is known as a perpetual motion machine of the 1st kind which is not probable.

• The first significance is related to the law of conservation of energy, heat, and work; both are different forms of the same entity known as energy which is conserved.

• Whenever a definite quantity of one kind of energy disappears, an accurately corresponding amount of some other kind must appear.

• The energy of an isolated system is constant

 

Is there a reason the universe obeys the Second Law of Thermodynamics other than…it just does?

     No, the second law says everything cools unless energy is added. The universe cannot be hot, then cold, then hot then cold. It can only be hot then cold. Gravity is far too weak to create the fusion reaction. Our observable universe has cooled from the very first second the big bang happened. That is the way the second law works. The energy we witness is due to a high speed collision between two giant objects at an astronomical speed in a static, already existing universe.

Interesting applications of thermodynamics in our daily life:-

    Thermodynamics in common usage in engineering is the study of energy and its various interconversions from one form to another. Thermodynamics has several types of Applications in our daily life: Fossil-fueled steam power plants, Spark-ignition engines and Jet engines.

     All types of vehicles that we use, cars, motorcycles, trucks, ships, aeroplanes and many other types work on the basis of the second law of thermodynamics and Carnot Cycle.

    Even cooling machines, such as refrigerators and air conditioners, actually use heat, simply reversing the usual process by which particles are heated. The refrigerator pulls heat from its inner compartment-the area where food and other perishables are stored-and transfers it to the region outside. This is why the back of a refrigerator is warm.

    So the refrigerators, deep freezers, industrial refrigeration systems, all types of air-conditioning systems, heat pumps, etc. work on the basis of the second law of thermodynamics. Also heat exchangers, evaporators, condensers, radiators, coolers, heaters are examples of Thermodynamics. As The concept of heat transfer is used in this wide range of devices . Also heat transfer is one of the important fields of thermodynamics, which relates to transfer of heat between two media.