The science that studies thermal phenomena isthermodynamics. Physics considers it as one of its sections, which allows us to draw certain conclusions, based on the representation of matter in the form of a molecular system.
Thermodynamics, whose definitions are based onthe foundation of the facts obtained by experience, does not use the accumulated knowledge about the internal structure of matter. However, in some cases, this science uses molecular-kinetic models to clearly illustrate its conclusions.
Support of thermodynamics - general patternsprocesses occurring when the thermal energy changes, as well as the properties of the macroscopic system, which is considered in the state of balance. The most significant phenomenon occurring in a complex of substances is equalization of the temperature characteristics of all its parts.
The most important thermodynamic concept isthe internal energy that any body possesses. It is enclosed in the element itself. Molecular-kinetic interpretation of internal energy is a quantity that is the sum of the kinetic activity of molecules and atoms, as well as the potential of their interaction with each other. Hence the law discovered by Joel. His confirmation was multiple experiments. They justified the fact that, in particular, an ideal gas has an internal energy, formed from the kinetic activity of all its particles, which are in a chaotic and erratic motion under the influence of heat.
Work in thermodynamics changes the activity of the body.The impact of forces that affect the internal energy of the system can have both a positive and a negative value. In those cases where, for example, a gaseous substance is subjected to a compression process that takes place in a cylindrical container under the pressure of a piston, the forces acting on it perform some kind of work characterized by a positive value. At the same time, there are opposite phenomena. Gas makes a negative work of the same magnitude over the piston that acts on it. The actions produced by the substance are in direct proportion to the area of the existing piston, its displacement, and also the pressure of the body. The work in thermodynamics, which is accomplished by gas, is positive for its expansion, and for compression, it is negative. The magnitude of this action is directly dependent on the path by which the transition of matter from the initial position to the final one was made.
Work in the thermodynamics of solid and liquid bodiesdiffers in that they very slightly change the volume. In this connection, the influence of forces is often neglected. However, the result of the work on the substance of the work may be a change in its internal activity. For example, when drilling metal parts, their temperature rises. This fact is evidence of the growth of internal energy. This process is irreversible, since it can not be carried out in the opposite direction.
Work in thermodynamics refers to its basicphysical quantities. Its measurement is performed in Joules. The magnitude of this indicator is in direct proportion to the way in which the system passes from the initial state to the final state. This action does not apply to body state functions. It is a function of the process itself.
Work in thermodynamics, the definition of whichis made according to the available formulas, is the difference between the amount of heat supplied and discharged in the period of a closed cycle. The value of this indicator depends on the type of process. If the system gives away its energy, it means that the action is more positive, and if it receives - the negative.
