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Chapter 20

The First Law of Thermodynamics

Термодинамические системы
Термодинамические системы
A thermodynamic system is a set of objects whose thermodynamic properties are of interest. The system is considered to be embedded in its surroundings or ...
Работа, выполненная при изменении объема
Работа, выполненная при изменении объема
In mechanics, work is done on an object when the force acting on it displaces the object. In thermodynamics, work done on a system can be estimated when ...
Путь между состояниями термодинамики
Путь между состояниями термодинамики
Consider the two thermodynamic processes involving an ideal gas that are represented by paths AC and ABC in Figure 1: In the first process for path A to ...
Тепло и свободное расширение
Тепло и свободное расширение
The work done by a thermodynamic system depends not only on the initial and final states but also on the intermediate states—that is, on the path. ...
Внутренняя энергия
Внутренняя энергия
The internal energy of a thermodynamic system is the sum of the kinetic and potential energies of all the molecules or entities in the system. The kinetic ...
Первый закон термодинамики
Первый закон термодинамики
A change in the internal energy of a system depends on the the net heat transfer into the system and the net work done by the system. The first law of ...
Первый закон термодинамики: решение проблем
Первый закон термодинамики: решение проблем
The first law of thermodynamics states that the change in internal energy of the system is equal to the net heat transfer into the system minus the net ...
Циклические процессы и изолированные системы
Циклические процессы и изолированные системы
A thermodynamic system with zero heat exchange and work is an isolated system. For these systems, the internal energy remains constant. In the case of a ...
Изотермические процессы
Изотермические процессы
A thermodynamic process that occurs at constant temperature is called an isothermal process. Heat slowly flows into the system or out of the system to ...
Изохорные и изобарические процессы
Изохорные и изобарические процессы
A thermodynamic process that occurs at constant volume is called an isochoric process. According to the first law of thermodynamics, heat supplied or ...
Теплоемкость идеального газа I
Теплоемкость идеального газа I
Heat capacity is the ratio of heat absorbed by the substance corresponding to its temperature change. It is also called thermal capacity and the SI unit ...
Теплоемкость идеального газа II
Теплоемкость идеального газа II
For a system that undergoes a thermodynamic process at a constant volume condition, the heat absorbed is used only to increase the system's internal ...
Теплоемкость идеального газа III
Теплоемкость идеального газа III
The number of independent ways a gas molecule can move along straight line, rotate, and vibrate is called its degrees of freedom. Supposing d represents ...
Адиабатические процессы для идеального газа
Адиабатические процессы для идеального газа
When an ideal gas is compressed adiabatically, that is, without adding heat, work is done on it, and its temperature increases. In an adiabatic expansion, ...
Давление и объем в адиабатическом процессе
Давление и объем в адиабатическом процессе
Free expansion of a gas is an adiabatic process. However, there are few differences between free expansion and adiabatic expansion. During free expansion, ...
Работа, выполняемая в адиабатическом процессе
Работа, выполняемая в адиабатическом процессе
Consider the adiabatic compression of an ideal gas in the cylinder of an automobile diesel engine. The gasoline vapor is injected into the cylinder of an ...
Термодинамические потенциалы
Термодинамические потенциалы
Thermodynamic potentials are state functions that are extremely useful in analyzing a thermodynamic system. They have dimensions of energy. The four ...
Термодинамические соотношения Максвелла
Термодинамические соотношения Максвелла
Maxwell's thermodynamic relations are very useful in solving problems in thermodynamics. Each of Maxwell's relations relates a partial ...
Эффект Джоуля — Томсона
Эффект Джоуля — Томсона
The Joule-Thomson effect, also known as the Joule-Kelvin effect, describes the temperature change of a fluid when it is forced through a valve or porous ...
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