Here is a concept map about thermodynamics. First, there are should have a property that we can assign to the state of any system, macroscopic or not. Then, We define a system as closed or isolated to one that is contained in a container whose walls are insulating, rigid, and waterproof. According to the practice, the force exerted per unit area that the rest of the fluid makes on any element of the volume is constant. In the absence of forces, the particle keeps its kinetic energy constant.