Introduction to

# Thermodynamics

Have you spent a moment wondering about heat? I have a guarantee to you(+1 year warantee) that this is a major component in classical physics and that it is way more complex and significant than you think. Of course, we exist to simplify this complicated phenomenon just for you, so welcome to an Introduction to Thermodynamics.

Now that we know why we're here, let's dive right in. In the simplest terms, Thermodynamics is a branch of Classical Physics that has everything to do and mess with heat, work and energy. It is none of our business to see what the universe is doing with these quantities, but you know curiosity and humans, who are always interested in bothering others.

Alright, so we know now what this fancy term of thermodynamics means. Now that we know that, let's begin by delving slightly into the depths. We'll have a quick overview of temperature and heat, since I feel its a point of confusion for many.

Heat: Heat is basically a form of energy. Now if you read our article based on Work, energy and power, you should be knowing what this term of 'energy' actually means and knowing that it is measured in Joules.

Temperature: Temperature is not energy but it loves to mess with energy. Temperature is basically the sum of Kinetic Energy of the molecules of the body. So if I have a particular object, like let's say a vessel with heating water, the temperature is the sum of kinetic energy of the molecules of the body. So it's like molecule 1 + molecule 2 + molecule 3 and so on and so forth for all the molecules in the body. Now kinetic energy has nothing to do with how bored you're feeling while reading this article(it's exactly the opposite) and you can understand more right here. Temperature is measured in various different units including degree Celsius and Fahrenheit, but the SI system recognises Kelvins being the unit for temperature.

Now celsius was developed for weather and farehnheit was developed for health, but as we know today, physicists take enjoyment in doing complex calculations and coming up with better units, and Kelvins is the unit in this case.

Great. You now know what the terms 'Temperature' and 'Heat' means, and that they cannot be used interchangeably.

Specific heat capacity:

Fine, let's get a little bit deeper and understand the concept of specific heat capacity. In the simplest it can be, specific heat capacity of a substance is basically the amount required to heat 1 gram of substance by 1 degree celsius.

This means, the amount of heat required to bring 1 degree celsius of kinetic energy to a body of mass 1 gram. Therefore, while the heat applied to two different bodies of different quantities may be the same, the temperature may not, since the kinetic energy is not equivalent!

Now that we understood several key terminologies of thermodynamics, we'll conclude this article by understanding the three laws of thermodynamics, since this is only the introduction to thermodynamics. If you're interested in Crash Course: Thermodynamics or the series, upgrade to premium.

Right, we must now learn the three laws of thermodynamics.Â

Unlike the three laws of Newton, the laws of thermodynamics may not hold in every situation. Also, there's a zeroth law as well!

0th law: The 0th law of thermodynamics states that 'If two systems are in thermal equilibrium with a 3rd system, they're also in thermal equilibrium with each other'. It's rather simple. If we have an ice, or system 1, water, or system 2 and the hot air, system 3. Now if the ice is in thermal equilibrium with the hot air(it means it has already melted) and the water is also in thermal equilibrium with the hot air, it means the (former)ice and the water are in thermal equilibrium. This term simply means thermally equal, or having the same temperature.

1st law: The first law is all about the law of conservation of energy. It states that the energy in the (doubted)existent universe is constant. The law describes how the energy can be transferred between systems and surroundings, but the total energy remains constant.

2nd law: Here we see a beautiful word come into picture, 'Entropy'. The 2nd law of thermodynamics is a key law that describes 'The entropy of an isolated system will increase'. Entropy has all to do with the total randomness in a system. If you'd like to learn more about entropy, subscribe to premium to get access to a simplified article. For example, if I take a glass of water, and drop some ink into it, at first it is not random at all, the ink is in one place; but over time, we realise the ink spreads through the water increasing the entropy.

3rd law: The third and last law of thermodynamics states that as a system reaches absolute zero, the entropy of the system also becomes constant. The third law of thermodynamics describes that when we reach to the lowest theoretically possible temperature, termed as 'absolute zero', the randomness, or entropy becomes constant.

Alright, we'll now have to temporarily conclude thermodynamics right here, but don't worry, if you're interested in this sector of Physics, upgrade to premium and receive more access to our articles related to thermodynamics. We learnt about key information ranging from specific heat capacity to the laws that govern thermodynamics. I hope to see you in the next article!