Energy

Energy, one of the basic physical categories. The concept of E. must always be considered together with the law of conservation and transformation of E., in which its entire essence is revealed. The often-cited definition in physics courses of E. as the ability to do work does not give this concept in its full completeness, since it lacks an indication of the connection between work and the transition of E. from one form to another. In reality, E. produces work only when transitioning from one form to another. The law of conservation and transformation of E. (first formulated by R. Mayer in 1842) states that E. can only transition from one form to another, but cannot be destroyed or created from nothing. The diverse forms of E. that we encounter daily—mechanical, thermal, radiant, electrical, etc.—continuously transitioning from one form to another, account for all the various processes that occur. Indeed, let us consider at least the following example: at a power plant, by burning peat, we obtain thermal E. at the expense of the chemical E. of the burning fuel; this thermal E. is transformed in a steam engine into mechanical E., which in turn is converted by means of a dynamo machine into electrical E. The latter in an electric bulb is partially transformed into radiant E. and partially into thermal E. We have a similar example in the case of living organisms; in them, at the expense of the chemical E. of the food being processed, we obtain the thermal and mechanical E. necessary for maintaining all life processes. No process is conceivable without the accompanying transition of E. from one form to another. But in this case, the second quantitative aspect of the law of conservation and transformation of E. is always precisely fulfilled. Instead of a certain amount of 'disappeared' E. of one form, an equivalent amount of E. of other forms always 'arises'. For example, if there is a transition of mechanical E. into thermal E., then one large calorie of heat always arises instead of the disappeared 427 kilogram-meters of mechanical E. (this ratio is called the mechanical equivalent of heat). E. is measured by the work that can be done by a given amount of E. when it transitions from one form to another; therefore the units of E. are the same as the units of work (see). Depending on the form of E., different units of work are used. For mechanical E., ergs or kg/m are usually used, for thermal E., as well as for chemical reactions, calories are used, for electrical E.—joules or watt-hours, etc. Mechanical E. can manifest in two forms: in the form of kinetic E. (energy of motion), for example, the E. of a moving body, which is equal to half the product of the mass of the body (m) by the square of its velocity (v), and in the form of potential E. (E. of position), an example of which can be the E. of a body raised to a certain height above the ground level. This E. is measured by the product of the weight of the body (p) by the height of its rise (h) E pot.= ph. Thermal E., on one hand, is as it were mechanical E., since it is the kinetic E. of the motion of individual atoms and molecules; however, due to the large number of molecules and the complete chaos of their motion, new qualities of thermal E. arise here, and one cannot, as the mechanists tried, reduce thermal E. to mechanical E. Chaotically moving molecules obey statistical laws, essentially different from the laws of ordinary mechanics. The transition of E. of different forms into each other is qualitatively not the same. Some transitions occur spontaneously, others require certain special conditions in the form of additional expenditure of E., etc. The transition of all forms of E. into thermal E. occurs most easily, for this reason all types of E. eventually turn into thermal E., which tends to distribute uniformly throughout space. This so-called 'dissipation of E.' led a number of idealist scientists to the idea of the thermal death of the universe (see Entropy). Thus, all types of E., turning into thermal E., as it were depreciate for us, since then they can no longer be used. The question of using reserves of E. has enormous significance for technology and industry. The science dealing with the study of energy resources and questions of their rational use—energetics—has particularly important significance in the USSR—a country of scientifically based and planned development. The main energy resources of the country—coal, oil, E. of falling water, wind, sun, etc.—must be systematically and correctly used for the maximum development of our technology and industry. The principle of conservation of E. is also applicable to living organisms. However, it is necessary to note that the mechanical transfer of it to these organisms can lead to incorrect results. From the point of view of conservation of E., only the amount of E. (caloric content) of the food consumed is important (see Isodynamics), but in reality the type of food from which they are obtained (proteins, fats, carbohydrates, etc.) plays an essential role. In accordance with the views of modern physics on the relationships existing between mass and E., the law of conservation of E. must be formulated more generally. Namely, it must be interpreted as the law of conservation and transformation of mass and E. The fact is that E. can be obtained at the expense of a change in mass and vice versa. To explain this, let us give the following example: if an oxygen atom is formed from 16 hydrogen atoms, then the law of conservation of mass is not fulfilled. Indeed, the atomic weight of oxygen=16.0, while the atomic weight of hydrogen=1.008, i.e., in this case a loss of mass is observed, equal to 1.008x16-16.000=0.128. This loss of mass is explained by the fact that it was released during the formation of the oxygen atom in the form of a corresponding amount of E. The relationship between mass (m) and E. (E) is the following where c is the speed of light in a vacuum. Due to the large magnitude of c² appearing in the denominator, a huge amount of E. is obtained from the disappearance of a small amount of mass.