Physics plays a crucial role in everything that encompasses mechanical engineering, and as a mechanical engineer, you must understand and be able to use the three thermal science disciplines in the work you do. The following briefly outlines each of these disciplines and touches on the importance of each in mechanical engineering work.




This heat discipline analyzes all thermal systems through the conservation of mass and conservation of energy principles. This branch deals with the basic relationships between heat (thermal energy) and all other forms of energy. One important thing to keep in mind is that there are three thermodynamic systems:


●        The open system - When the transfer of the mass and energy can take place across the system’s boundary.

●        The closed system - When the transfer of energy can take place across its boundary, but there is no transfer of mass.

●        The isolated system - When there is neither a transfer of mass nor energy across its boundary.


When performing calculations and determining the thermal properties of a system, an engineer will take into account the four laws of thermodynamics, which include:


●        The Zeroth Law - When all three thermodynamic systems are in equilibrium with one another.

●        The First Law - The first law states that energy cannot be created or destroyed; it can only change forms. In other words, the total energy of the universe remains the same, therefore, in a thermodynamic system, the heat supposed in a system will equal the net work produced by the system.

●        The Second Law - If the isolated system is not in equilibrium, it will increase over time, slowly approaching the maximum equilibrium value.

●        The Third Law - The entropy of the system will approach a constant minimum as the temperature approaches absolute zero.


These laws of thermodynamics are applied to nearly every device produced or invented, including the systems created and installed by Gausman and Moore engineers.


Fluid Mechanics


Fluid mechanics deals with the behavior of fluids either at rest or in motion. All the principles of fluid mechanics allow the study of fluids flowing through in interior of pipes (known as internal flow) as well as over surfaces (known as external flow). The concept of similitude is often used when scaling measurements on smaller, lab-sized models. Two important fundamentals that play a role in the study of fluid mechanics stem from Newton’s Second Law of Motion. 


●        Conservation of momentum principle. If there is a collision of two objects in an isolated system, and the total momentum of the objects before the collision equals the momentum of the objects after the collision, then the momentum lost by the first object will be equal to the momentum gained by the second object.

●        Mechanical energy equation: mechanical energy = kinetic energy + potential energy.


Each of these fundamentals plays an important role in our fluid mechanics studies here at Gausman and Moore for the development of our heating, cooling and ventilation systems, as well as any pumps.


Heat Transfer


This final thermal science discipline basically deals with the consequence of temperature differences, which is energy transfer. The three modes of heat transfer include:


●        Conduction. Heat temperature differences between two masses in thermal contact cause heat transfer to occur.

●        Convection. Heat is transferred to a moving fluid at the point of the surface of which the fluid flows. Convection incorporates both conduction and fluid flow.

●        Radiation. In this instant, heat is transferred in the form of radiant energy (wave motion) from one mass to another mass.


Calculating and applying each of these thermal science disciplines is important for our mechanical engineers as they are often required for many of our complex building systems. And Majority of our applications at Gausman and Moore require more than one of these modes. Check out our mechanical engineering page to learn more about our services.