Maria Rutkowska

Thermal Energy? Temperature? Particle Motion? Terms we hear on a daily basis in the science community, yet still have such deep meaning behind them. We would say that energy overall is the movement of particles; with the gain of kinetic energy they move faster and faster.

The term itself was first found in temperature, thermal energy, and particle motion: "Thermal energy is a type of
power produced by atomic and molecular particle movement within a substance. It was first discovered in 1847 by English physicist and mathematician James Prescott Joule, after whom the unit of energy Joule..." (Just Energy, 2021).

Experiments are an essential part of new discoveries. Whilst Joule was experimenting, he came across the idea of mechanical energy conversion "Joule realized that the more he manipulated the speed of a substance, the higher temperature it became. Because of this, thermal energy is often referred to as heat energy, but the two terms are not exactly the same."

This brings me to my next point, what do we associate and connote with heat? Temperature? Kinetic energy, or maybe even thermal energy? As stated, the two terms are not the same thing. The correlation between heat and thermal energy has referred to, whilst being studied at an extensive level, as thermodynamics (the study of energy transformation). Thermodynamics potentially revolves around four main laws:

According to the article titled "Thermal Energy:What is it?" 

  • "The zeroth law. It states that should one of two systems with equal heat flow encounter a third system; all three systems will share equal heat flow.

  •  The first law of thermodynamics is also referred to as the Law of Conservation of Energy. This law dictates that energy cannot be created or destroyed. The heat from a source will equal the heat used in a system, and only heat energy can be changed into other forms of energy.

  • The second law of thermodynamics states that no closed system will ever remain the same. The entropy of an isolated system will always increase. Entropy is a quantity that represents the absence of a system’s thermal energy for conversion into mechanical work; it is also understood as the degree of randomness in a system. Interacting systems of different temperatures will experience heat flow until both temperatures become the same. A higher temperature system will transfer heat until it is equal to that of the cooler object. For example, a cube of ice will not get colder, but rather, as it interacts with the system of its warmer surroundings it will melt, eventually becoming the same temperature as its environment.

  • The third law of thermodynamics tells us that the entropy of a thermal energy system will obtain a constant value when temperatures reach absolute zero."

Potentially, Joule’s Law is “The rate of heat production by a steady current in any part of an electrical circuit that is proportional to the resistance and to the square of the current, or, the internal energy of an ideal gas depends only on its temperature.” (Just, 2021) Temperature is the average kinetic energy inside an object. It is commonly measured globally by three scales: Fahrenheit (F), Celsius(C), and Kelvin(K).

To find out more about internal energy check our science behind weekly post.


Just, E. (2021, October 15). Thermal energy: A beginner's guide. Just Energy. Retrieved November 15, 2021, from https://justenergy.com/blog/thermal-energy-what-it-is-how-it-works-environmental-impact/.

Schools, S. (n.d.). Thermal energy. Thermal Energy - Knowledge Bank - Solar Schools. Retrieved November 15, 2021, from https://www.solarschools.net/knowledge- bank/energy/types/thermal#:~:text=Thermal%20energy%20(also%20called%20heat,substance%20is%20called%20thermal%20