Kinetic energy

“ There are various forms of non-kinetic energy, such as, e.g., the energy of “position” of a resting body, the heat of a body of higher temperature than its surroundings, which Mechanics treats as equivalent to “kinetic” energy, because they are theoretically capable of being converted into it. And these forms of non-kinetic energy are qualitatively different both from energy of actual motion and from each other. It is by a mere abstraction that we treat them as identical because they are, for certain special purposes, equivalent. ”

“ It must be evident that under a dynamical theory of gravitation, when a mass is lifted, the energy expended in lifting cannot be converted into "potential" energy, but must be converted into kinetic energy, in imparting motion to the particles impinging upon the upper side of the mass, and which tend to urge it downwards. Conversely, when the mass falls, kinetic energy is transferred from the particles of the medium to the mass. As a general principle, therefore, by the abandonment of the theory of "action at a distance" there can be no such entity as "potential " energy at all. ”

“ It dominates physics under the name of the theory of kinetic energy. The minds of men in our own time are so strongly impregnated with this idea that most scientists of ordinary culture get no glimpse of the world of phenomena but by means of this conception. And yet it is only an hypothesis. But it is so simple, so intuitive, and appears to be so thoroughly verified by experiment, that we have ceased to recognize its arbitrary and unnecessarily contingent character. Many physicists from this standpoint consider the kinetic theory as an imperishable monument. ”

“ A mass of matter moves because energy has been spent upon it, and has acquired energy equal to the work done on it, and this is believed to hold true, no matter what the kind of energy was that moved it. If a body moves, it moves because another body has exerted pressure upon it, and its energy is called kinetic energy; but a body may be subject to pressure and not move appreciably, and then the body is said to possess potential energy. ”

“ From the standpoint of the principle of relativity, one of the most interesting quantities in mechanics is the so-called kinetic energy, which is the increase in energy attributed to a body when it is set in motion with respect to an arbitrarily chosen point of rest. ”

“ This "work" energy is assumed to be manifested, in the first place, as energy of motion. As already pointed out, no expenditure of energy can be associated with a linear motion of the mass, since that motion is under no restraint, but in virtue of the initial central attraction or gravitative strain, the form of energy first communicated may be that of kinetic energy of rotation. Its transmission to the mass will cause the latter to revolve about some axis of symmetry within itself. ”

“ If we rest on the synthesis here described, the energy of the matter, even the thermal part, appears largely as potential energy of strain in the aether which interacts with the kinetic energy associated with disturbances involving finite velocity of matter. It may, however, be maintained that an ultimate analysis would go deeper, and resolve all phenomena of elastic resilience into consequences of the kinetic stability of steady motional states, so that only motions, but not strains, would remain. ”

“ A moving cricket-ball is a good example of kinetic energy. In its passage through the air it possesses kinetic energy, and should the ball catch your head you know pretty well what is the effect. A steamship moving and a running railway-train are kept in motion by the energy imparted to them from coal, and we know what tremendous energy a steamship or a railway-train has, as when a collision occurs there is a terrific smash-up. Our earth is another magnificent store of energy in its rotation every twenty-four hours ”

“ According to our hypothesis we assume kinetic energy to exist wherever there is magnetic force, that is, in general, in every part of the field. This energy exists, therefore, in some kind of motion of the matter in every portion of space ”

“ For example, the potential energy of our stone may be taken to be the kinetic energy it would acquire in falling to the surface of the earth, or what it would acquire in falling down a well to the center of the earth, or any assigned lesser distance. It does not matter which we take, so long as we stick to our decision. ”

“ A bent bow, a piece of stretched rubber, a suspended weight, the water above a mill dam, all have the capability of causing motion and all have potential energy. Examples of kinetic energy are found in the movements of machinery, in steam and electricity, in winds, and in currents of water. Kinetic is the active, and potential the inactive, form of energy.
70.As the atoms of hydrogen and oxygen that make up the molecules of water separate, they unite with atoms of their own kind—the hydrogen with hydrogen and the oxygen with oxygen atoms. ”

“ Suppose now that it receives an impulse, it will begin to move with a velocity inversely proportional to its mass, on the one hand, and directly proportional to the strength of the impulse, on the other, and will possess kinetic energy, in virtue of which it will not only continue to move for ever if unimpeded, but if it impinges on another such particle, it will impart more or less of its motion, to the latter. Let it be conceived that the particle acquires a tendency to move, and that nevertheless it does not move. ”