Investigating How to Use the Definite Integral in the Calculation of Thermodynamic Quantities

This article is written under the title (Investigation of how to use the definite integral to calculate thermodynamic quantities). The method of this research is descriptive; In order to collect sources, international articles from reputable scientific sites and new and pristine books have been used to enrich the article. The aim of the present research is to know the basic parameters and choose the appropriate device for solving thermodynamic problems by the basic table of indefinite integral. To calculate the thermodynamic quantities, the basic integration table and curves of pressure, work and energy functions of thermodynamic systems based on the enclosed surface were used. In this calculation, it was observed that the pressure calculation is done in two situations with two mathematical methods: the first one with constant pressure which is done from the basic integral tables, the second one with variable pressure which in this case the pressure-volume function is done according to the mathematical equation. takes In general, complex polytrophic processes were calculated in the thermodynamic system with constant price change.