In thermodynamics, there are three key laws which form the basis of all thermodynamic systems at equilibrium. These laws are not just crucial in thermodynamics, but they’re also an important fundamental law of physics and applied in natural sciences. The three laws follow a simple figure identical, the first law, the second law and the third law. Below we will discuss the First Law.

What Is The First Law of Thermodynamics

The first law of thermodynamics, the most well-known out of the three, is also known as the law of conservation of energy. The law states:

Energy can neither be created nor destroyed; it can only be transferred or changed from one form to another.

 Energy can be defined as a property that can be transferred to an object to perform work on or heat the object.

For a thermodynamic process, the first law is defined as:

Delta Usystem = Q – W

Describing the above equation in words: The change in internal energy of a system is equal to the difference between heat added to the system and the work done by the system with its environment (Q = Heat transferred, W = Work done by the system).  The equation shows that any kind of energy change of the system will result in an energy change to its surroundings (via either heat or work). This shows energy is neither created nor destroyed, it’s being transformed from one form to another.

Practical examples

A great example to help people understand the first law is the process of exploding dynamite. In this example, chemical energy is converted to kinetic energy. If we add up all the forms of energy released in the explosion, including the kinetic and potential energy of the pieces, heat and sound we will be left with the decrease in chemical energy from the dynamite combusting.

The most common application of the first law is a car engine. In an engine, heat is converted to mechanical energy. However, in this example, not all the energy produced, is the energy desired, which is mechanical energy to propel the car. During the process there is a lot of wasted heat energy, although it does not suit us, it abides by the first law, that energy isn’t created nor destroyed, it can only be transferred from one form to another.

Follow My Social Media: LinkedIn, Twitter, Facebook