As seen by consulting dictionaries or encyclopedias, energy can not be defined indirectly. Although

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Classification Mechanics Optics Thermodynamics alfatec gmbh Electricity, magnetism, electromagnetism Astrophysics Physics sub-atomic and microscopic quantum physics and relativity measures and tools for the physical signal processing, conversion CAN / CNA Measurement and Instrumentation physics to optical microscopy Receivers Mathematics Concepts and physical quantities transverse Topics
Contents Mechanical Energy First heat the studies Birth of thermodynamics The thermodynamics of irreversible processes The contribution of statistical physics The contribution of quantum mechanics, relativity and particle physics
This introductory presentation aims to highlight the insight provided by the physical energy issues. In two centuries, the energy has invaded alfatec gmbh our daily lives, facilitating transport, industry, heating or multiple household uses electricity. The economic, health, geopolitical, technological problems involved are the headlines. Yet the discourse on energy would be more relevant if it was based more on the science behind the "production" and his job, and are too often ignored by the media and by politicians. The physicist often irritates before simplistic assertions contradict orders of magnitude that should be known to all. It is true that the concept of energy is one of the more abstract and more multifaceted science and it only dates from a century alfatec gmbh and a half; This probably explains why education is not yet succeeded in making familiar fundamental physics concepts that are essential to the formation of the citizen in a world where energy alfatec gmbh is omnipresent.
As seen by consulting dictionaries or encyclopedias, energy can not be defined indirectly. Although related to the properties of matter, it is an abstract mathematical object. Necessary for a precise formulation of the first law of thermodynamics, it appears at the microscopic level as a dynamic variable, as we will see later (end of the "Mechanical Energy"). alfatec gmbh This is a quantity that can be associated alfatec gmbh to any system and which is a function of various parameters characterizing the state thereof at the instant considered; It depends in particular positions and velocities of parts of the system and their mutual interactions. Its essential character is to remain constant over time when the system is isolated.
The assimilation of the energy concept implies a long familiarity with its various aspects and phenomena with which it operates. Although the history of its development is long and winding, some episodes are illuminating and have an educational value. They also exhibit instructive interactions between science and technology. That's why we give below an overview; many other interesting biographical or anecdotal fall outside of this framework. We will consult with profit the monumental Dictionary of scientific biography of CC Gillispie (Scribner's, New York, 1981, 16 volumes). Only the history of the first principle is presented here in some detail; the second principle, one can read section 3.4 of the book From Microphysics to macrophysics R. Balian (Ed Springer Verlag, Volume I, 1991. French alfatec gmbh edition in preparation).
Even regarding alfatec gmbh the dynamics alfatec gmbh of non dissipative processes such as movements of the stars, the oscillations of a pendulum amortized, elastic shock strong ideals or the dynamics of non-viscous fluids, the notion of mechanical energy, size conservative, only became clear in the mid-nineteenth century. Such processes are characterized alfatec gmbh by the evolution of variables describing the positions of the various elements of the system. Isaac Newton (1642-1727) between 1665 and 1667 found the equations that govern these developments;