Читать книгу Force and Energy; A Theory of Dynamics - Allen Grant - Страница 6
ОглавлениеENERGY.
An Energy is a power which resists or retards aggregative motion, while it initiates or accelerates separative motion, in two or more particles of ponderable matter or of the ethereal medium.
All particles, or aggregates of particles, not actually in contact with one another in stable equilibrium at the absolute zero of temperature, are kept apart by an Energy or separative Power of some sort, which prevents them from aggregating as they would otherwise do under the influence of the Forces inherent in them. Thus the moon is prevented from falling upon the earth, and the earth from falling into the sun, by the Energy of their respective orbital motions. A ball shot from a cannon into the air is prevented from falling by the Energy of its upward flight. A red-hot poker has its particles kept apart by the Energy of heat. In every case, so soon as the Energy is dissipated (as hereafter explained) the ball yields to the aggregative Power of Gravitation, and the poker contracts to its ordinary dimensions; while there is no reason to doubt that under similar circumstances the moon and the earth will aggregate with the sun. The particles of water are kept in the liquid state by the Energy known as latent heat,[2] and so are those of steam: when the ‘latent heat’ is dissipated, the steam condenses and the water freezes. There are many apparent exceptions; but they will be considered at later stages of the argument. For the present, the reader must be content to understand the word Energy (when used in this treatise) only in the sense here given to it of a Power which resists or retards aggregation.
Energies also initiate separative motions. Thus, a cannon ball is raised by Energy to a distance from the main mass of the earth which usually holds it bound by Gravitation on its surface. A poker placed in the fire has its particles separated from one another by the Energy of Heat. When ice melts or water is converted into steam, the same Energy similarly severs their particles from one another and places them in positions of relative freedom. In the electrolysis of water the Energy of the galvanic current tears asunder the atoms of hydrogen and oxygen from their close union in the compound molecule. In short, wherever we see masses or particles in the act of separating from one another, we know that the separation is due to some Energy.
