The law of conservation and transformation of energy is one of the most important tenets of physics. Consider the history of its appearance, as well as the main areas of application.
Pages of History
First, find out who discovered the law of conservation andenergy conversion. In 1841, the English physicist Joule and the Russian scientist Lenz conducted parallel experiments, which resulted in the scientists succeeding in practice in finding out the connection between mechanical work and heat.
Numerous studies conducted by physicistsin different parts of our planet, predetermined the discovery of the law of conservation and transformation of energy. In the middle of the nineteenth century, the German scientist Mayer was given his wording. The scientist tried to summarize all the information about electricity, mechanical movement, magnetism, human physiology, which existed in that period of time.
Around the same period, similar thoughts were expressed by scientists in Denmark, England, Germany.
Experiments with heat
Despite the diversity of ideas concerningwarmth, a complete picture of it was given only by Russian scientist Mikhail Vasilyevich Lomonosov. Contemporaries did not support his ideas; they believed that heat was not associated with the movement of the smallest particles that make up matter.
The law of conservation and transformation of mechanicalThe energy proposed by Lomonosov was supported only after Rumford was able to prove the presence of movement of particles inside a substance during experiments.
Для получения теплоты физик Дэви пытался плавить ice, rubbing together two pieces of ice. He hypothesized that heat was regarded as the oscillatory motion of particles of matter.
The law of conservation and transformation of energy according to Mayerassumed the immutability of the forces causing the appearance of heat. A similar idea was criticized by other scientists, who reminded that force is related to speed and mass, therefore, its value could not remain unchanged.
At the end of the nineteenth century, Meyer summarized hisideas in the brochure and tried to solve the actual problem of warmth. How was the law of conservation and transformation of energy used at that time? In mechanics, there was no consensus about how to obtain, the transformation of energy, so until the end of the nineteenth century, this question remained open.
Feature of the law
The law of conservation and transformation of energy isone of the fundamental, allowing, under certain conditions, to measure physical quantities. It is called the first law of thermodynamics, the main object of which is the preservation of this value in the conditions of an isolated system.
The law of conservation and transformation of energyestablishes the dependence of the amount of heat on various factors. In the course of experimental studies conducted by Mayer, Helmholtz, and Joule, various types of energy were identified: potential, kinetic. The combination of these species was called mechanical, chemical, electrical, thermal.
The law of conservation and transformation of energy had the following formulation: "The change in kinetic energy is equal to the change in potential energy."
Meyer came to the conclusion that all varieties of this magnitude are able to turn into each other if the total amount of heat remains unchanged.
Mathematical expression
For example, the energy balance acts as a quantitative expression of the law in the chemical industry.
The law of conservation and transformation of energyestablishes a relationship between the amount of thermal energy that falls into the zone of interaction of various substances, with the amount that leaves this zone.
The transfer of one type of energy to another does not mean that it disappears. No, there is only its transformation into a different form.
In this case, there is a relationship:work is energy. The law of conservation and transformation of energy implies the constancy of this quantity (its total amount) in any processes occurring in an isolated system. This indicates that in the process of transition from one species to another, quantitative equivalence is observed. In order to give a quantitative characteristic of different types of motion, nuclear, chemical, electromagnetic, thermal energy has been introduced into physics.
Modern wording
How to read the law of conservation and transformationenergy in our day? Classical physics offers a mathematical notation of this postulate in the form of a generalized equation of state of a thermodynamic closed system:
W = Wk + Wp + U
This equation shows that the total mechanical energy of a closed system is defined as the sum of the kinetic, potential, internal energies.
The law of conservation and transformation of energy, the formula of which was presented above, explains the invariance of this physical quantity in a closed system.
The main disadvantage of a mathematical notation is its relevance only for a closed thermodynamic system.
Unclosed systems
Given the principle of increments, it is quite possibleto extend the law of conservation of energy to unlocked physical systems. This principle recommends writing mathematical equations related to the description of the state of the system, not in absolute terms, but in their numerical increments.
To fully take into account all formsenergy, it was proposed to add to the classical equation of an ideal system the sum of energy increments, which are caused by changes in the state of the analyzed system under the influence of various field forms.
In a generalized form, the equation of state has the following form:
dW = Σi Ui dqi + Σj Uj dqj
This equation is considered the most complete in modern physics. It became the basis of the law of conservation and transformation of energy.
Value
In science there are no exceptions to this law, hemanages all natural phenomena. It is on the basis of this postulate that hypotheses about various engines can be put forward, including refutations of the reality of the development of the eternal mechanism. It can be used in all cases when it is necessary to explain the transitions of one type of energy to another.
Use in mechanics
Как читается закон сохранения и превращения energy now? Its essence lies in the transition of one type of this value to another, but at the same time its overall value remains unchanged. Those systems in which mechanical processes are carried out are called conservative. Such systems are idealized, that is, they do not take into account frictional forces, other types of resistance, which cause the dissipation of mechanical energy.
In a conservative system, only mutual transitions of potential energy into kinetic flow.
The work of the forces that operate in such a systemon the body, not related to the shape of the path. Its value depends on the final and initial position of the body. As an example of forces of this kind in physics, gravity is considered. In a conservative system, the magnitude of the work force in a closed area is zero, and the energy conservation law will be as follows: "In a conservative closed system, the sum of the potential and kinetic energy of the bodies that make up the system remains unchanged."
For example, in the case of a free fall of a body, the transition of potential energy into a kinetic form occurs, and the total value of these types does not change.
Finally
Mechanical work can be considered as the only way of mutual transition of mechanical motion into other forms of matter.
This law has found application in technology.After turning off the car engine, there is a gradual loss of kinetic energy, followed by a stop of the vehicle. Studies have shown that in this case there is a release of a certain amount of heat, therefore, the rubbing bodies heat up, increasing their internal energy. In the case of friction or any resistance to movement, a transition of mechanical energy into an internal quantity is observed, which indicates the correctness of the law.
Its modern formulation is:“The energy of an isolated system does not disappear into nowhere, does not appear from nowhere. In any phenomena that exist within the system, there is a transition of one type of energy to another, transfer from one body to another, without a quantitative change. ”
After the discovery of this law, physicists do not leavethe idea of creating a perpetual motion machine in which, with a closed cycle, there would be no change in the amount of heat transferred by the system to the surrounding world, in comparison with the heat received from the outside. Such a machine could become an inexhaustible source of heat, a way to solve the energy problem of mankind.
