Isolated system in thermodynamics: definition, features and examples

2024 Author: Henry Conors | [email protected]. Last modified: 2024-02-12 02:43

There are several types of systems in thermodynamics: isolated and non-isolated. Where they are found, when they are applied, shows how useful they can be and how to care for them. Otherwise, if such systems turn out to be harmful to human work, how to get rid of them.

What is this?

An isolated system is absolutely any accumulation of atoms and molecules (a thing, a planet, a human body) that retains the energy of all matter. Such a system is completely isolated from the outside world, it is also called closed.

The essence of an isolated system is that, with all its desire, it will not share heat, does not squander energy, the substance will have to be taken away from it by force. For example, you can look at the aquarium. Processes take place inside it: fish die, water deteriorates, shells collapse. But the aquarium does not come into contact with the external environment.

Another example of an isolated system is an iron - it will not spend energy itself, it will not share substances. Such a phenomenon is observed in tank engines, the solar system - in everything that does not share energy with others.

To closed isolated systemsyou can’t take the car - it moves at a certain speed by itself! It also does not include teapots, plants, living organisms - they share substances with the outside world. Living organisms emit metabolic products, plants - oxygen, a kettle - steam when boiling.

Interesting fact: a closed system is called a system where the sum of the produced forces and work is equal to zero, and isolated - where the bodies simply act separately from other systems. At the same time, an isolated system is not always closed, but a closed system will necessarily be isolated.

Movement is a trap

There is one caveat: they cannot move by themselves, but if someone moves them, then the rule is not violated. So, if you take an isolated system and throw it from a height, accidentally drop it, drop it from a parachute - it doesn’t matter, it will not cease to be isolated. Unless, of course, it is broken during such actions - the same bottle of water thrown from a height will release all the water out - share matter with other systems - which means that the system will no longer be closed.

This description fits a pistol and a bullet - does not work without a finger on the trigger, a heavy body and the Earth - nothing happens if you do not push the body to the ground.

Heat should also be taken into account

An isolated system in thermodynamics is a macrobody that never shares anything at all: energy, matter and heat do not go beyond the limits of the system. An example is a thermos. It keeps the degree of tea poured into it, a drink without human intervention forcibly (open and pourhimself) will not share, and does not spend energy anywhere.

Moreover, an isolated system always strives to reach thermodynamic equilibrium, and someone else is needed to bring it out of this state. That is, if we give an example of the same thermos, then if it is in the environment for a long time, the tea will still cool down. Therefore, a person is needed who will again fill it with hot tea, and the system will again be thermodynamically isolated.

Why is it needed?

The concept of an isolated system covers many mechanisms, systems and ecosystems. A person needs an understanding of how they are arranged in order to properly care for them. If this is an aquarium, then before climbing into it with arms and legs, trying to clean it, you must first see how to do everything so as not to disturb it. If these are mechanisms or equipment - how to use them, so that later it would not be excruciatingly painful to repair them.

At the same time, if we take it on a global scale, the desert is also an isolated system: certain mechanisms of vital activity take place inside it, which do not go beyond it. Forests, steppes, volcanoes, and the atmosphere serve as relatively isolated ecosystems. People, not understanding how they work, sometimes do not realize themselves the scale of trouble they create.

There is one more "but". An isolated system will never exist completely separate from other systems. But this concept exists. It is convenient for making calculations in mathematics, thermodynamics, chemistry and physics. Allthe energy and matter that an isolated system emits are taken as zero and operate with the numbers that are needed at the moment.

Isolate the non-isolated

Even an open system can become isolated if something separates it from the environment. An adiabatic system acts as a partition, which serves as a shell for an open system, making it closed. It can be compared to foil wrapped around an object, trying to protect it from the sun's rays.

If you look at it in a broader sense, then the atmosphere for the Earth can serve as an example - it protects the planet from cosmic influence and serves as a shell that gives us life.

There is a law of conservation of momentum for a closed isolated system: The sum of impulses in a closed system remains constant, no matter how the bodies interact with each other inside the system. And rightly so: although the strength of impulses can change with time, circumstances, opportunities, their sum will still remain constant.

A thick dot at the end…

Thus, the conclusion suggests itself as follows:

• An isolated system is as independent of its environment as possible, producing energy, work and matter within itself. It will remain constant, while striving for balance.
• A closed isolated system will also not depend on environmental conditions, it will not distinguish anything from itself, but the work in it will be equal to zero in total. That is, the law of conservation of momentum will beextend to such a system rather than to an open one.
• An isolated system in thermodynamics will not depend on the heat of the environment. Builders try to achieve this state when they insulate houses. By the way, foam can easily serve as an adiabatic shell for a house, making it an insulated system.
• An isolated system does not exist in principle: everything interacts with something. If you close the aquarium, the water will be poor in oxygen, and the fish will die. They remain in the red anyway.

Science needs isolated systems in order to have the purity of the experiment - some quantities can be neglected. But in life - they need proper care and use.