the branch of physical science that deals with the relations between heat and other forms of energy (such as mechanical, electrical, or chemical energy), and, by extension, of the relationships between all forms of energy
Let's start with the most basic thing that is to clarify what thermodynamics is.
Thermodynamics is in charge of studying heat transfers, the capacity of a system to produce work and how energy is converted. Systems that contain <u>particles </u>are studied in this area, rather than systems that contain atoms or molecules.
Now these systems are those that are part of the universe, such as a gas.
There are laws of thermodynamics to explain all this, and they are not theoretical studies but rather studies based on experiences that are directly associated with the aforementioned systems in a state of equilibrium.
These laws are:
Zero principle of thermodynamics: It establishes that when two bodies are in thermal equilibrium with a third one, they are in thermal equilibrium with each other.
First principle of thermodynamics: It establishes the relationship between work and the transferred heat that is exchanged in a system through internal energy.
Second principle of thermodynamics: It states that not all heat can be transformed into mechanical work, although all mechanical work can be transformed into heat.
Third principle of thermodynamics: It is the least important of the laws. It is related to the etropy of a substance that is null, and details its behavior when it approaches absolute zero.
The principle of conservation of momentum, states that if the sum of the forces acting on a system is null, the initial total momentum of the system before a collision equals the final total momentum of the system after the collision. The collision is completely inelastic, which means that the players remain stick to each other after the collision:
I mean, how about gravity for example! When you draw a free-body diagram, you will almost always have to include gravity. How about normal force, or static friction? There are defintely forces at hand.
