Potential energy

“ Since all forms of energy are essentially kinetic or potential, or the energy of heat-motion, it is sufficient if we examine the laws with regard to these.
A body is said to possess potential energy when in virtue of its position it can do work. A raised weight possesses potential energy, which, by a simple contrivance, may be converted into work; a bent bow and a wound-up spring possess energy of position, because of the separation of their molecules, which we may avail ourselves of by allowing them to fall back into their natural positions. ”

“ Further measurements on the transformations of other forms of energy, chemical energy and electrical energy, have shown that Joule's law of equivalents is general, and that the quantity of mechanical work represented by any form of energy remains undiminished after transformation, whatever the nature of that transformation.
Energy presents itself to us under two forms, potential and actual. Potential energy is slumbering energy, energy localized or locked up in the body. ”

“ Yet one can easily imagine a state of things in which oxygen might be deficient; and in a world so constituted it would have to be regularly laid on in pipes, like gas or water, if the people wished to have any fires.
All energy, then, is derived from the separation of two or more bodies having affinities for one another. So long as the bodies remain separate, the energy is said, in the technical slang of physics, to be potential; as soon as the bodies unite, and the energy is manifested as motion, it is said to be kinetic. ”

“ 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. ”

“ The oxygen and hydrogen now have potential energy, and, if they be allowed to combine, this will manifest itself as the light and heat of the explosion. These examples will serve to illustrate the nature of the changes which energy undergoes. These are of the nature of transferences of energy from one body to another, and of transformations from one mode or manifestation to another. The most important point that has been established during this century with regard to energy is that, throughout all its transferences and transformations, it can be neither created nor destroyed. ”

“ The true equivalent is this heat, plus the potential energy conferred upon the molecules by the placing of greater distances between them. This molecular potential energy is afterwards, on the cooling of the body, converted into heat.
Wherever two atoms capable of uniting together by their mutual attractions exist separately, they form a store of potential energy. Thus our woods, forests, and coal-fields on the one hand, and our atmospheric oxygen on the other, constitute a vast store of energy of this kind — vast, but far from infinite. ”

“ And we here again see that a complex energy has been transformed, in its first phenomenal condition, into potential energy, and that this potential energy is always expended in the second phase without loss or gain. ”

“ A similar distinction between actual and potential energy exists with regard to every form of force. If by any means you separate an atom of carbon from an atom of oxygen, you exert actual energy. The process is analogous to carrying up the weight. The atoms when separated possess potential energy,—they can rush together again, like the weight to the earth, and in doing so will give out the work which was expended on their separation. ”

“ The great underlying principle of either kinetic or potential energy rests in the fact, that wherever we have energy of any kind or sort, whether it be associated with water, wind, or Aether, there we have the capacity to do work, the amount of work depending upon the amount of energy that exists in the matter which is the vehicle of energy. ”

“ This increase is the evidence of a definite energy process by which certain particles or portions of the mass have in distortion gained energy of position—energy of separation—or potential energy relative to the centre of the sphere. In fact, if the mass were allowed to cool back to its normal condition, this energy might by a suitable arrangement be made available for some form of external work. ”

“ But experience furnishes innumerable examples of the production of kinetic energy in a body previously at rest, when no impact is discernible as the cause of that energy. In all such cases, the presence of a second body is a necessary condition; and the amount of kinetic energy, which its presence enables the first to gain, is strictly dependent on the relative positions of the two. Hence the phrase energy of position, which is frequently used as equivalent to potential energy. ”

“ In order to transform potential energy into actual energy, there is required the intervention of an additional awakening, stimulating, or exciting energy from without. This stimulating energy may be almost infinitesimal in amount and bears no quantitative relation to the amount of energy transformed. ”

“ LATENT ENERGY Thirdly, there is a vast store of potential energy which has become dormant in matter during the involution of the subtle into the gross, and by changing the condition of the matter some of this may be liberated and utilized, somewhat as latent energy in the form of heat may be liberated by a change in the condition of visible matter. ”

“ Let it be conceived that the particle acquires a tendency to move, and that nevertheless it does not move. It is then in a condition totally different from that in which it was at first. A cause competent to produce motion is operating upon it, but, for some reason or other, is unable to give rise to motion. If the obstacle is removed, the energy which was there, but could not manifest itself, at once gives rise to motion. While the restraint lasts, the energy of the particle is merely potential; and the case supposed illustrates what is meant by potential energy. ”

“ It is quite clear that the necessary energy is indeed afforded by the contraction, but it is not quite so easy to learn the precise character of the process by which the energy after disappearing from the potential form reappeared as heat. ”

“ The processes of growth, however, are of such a complex nature that it is impossible to state the governing energy conditions in their entirety, but, considering them merely in general fashion, it may be said that energy in various forms (potential, chemical, &c.) is stored in the tissues of the growing material. Now the source of this energy is the axial energy of the earth, and, as stated above, the luminous field is an incepting factor (there may be others) in the process of transformation, a factor whereby this axial energy is converted into certain new forms. ”

“ The form of energy is continually changing, but the sum of energy in the universe remains invariable and constant. Therefore, it seems to follow, there can be no specific vital phenomena. The energies concerned in the up-building, growth, and decay of the organism, and the sum of the functions performed by it, must be the exact resultant and equivalent of the potential energies stored in its material substance and the co-operative energies of its environment. ”

“ The vital energies are derived from the potential chemical energy accumulated in the immediate constituent principles of the organism. In the same way the consequent phenomenon of the vital phenomenon is in general a thermal phenomenon. The final form of vital energy is thermal energy. These three assertions as to the nature, the origin, and the final form of vital phenomena constitute the three fundamental principles, the three laws, of biological energetics.
Food, a Source of Heat. ”

“ Every transformation of a special kind of energy A is accompanied with a fall of potential of that particular kind of energy, including heat. But whilst for the other kinds of energy a transformation and therefore a loss of energy on the part of the kind sinking in potential is connected with the fall of the potential, with heat the case is different. ”

“ This energy is supposed to be partly potential and partly kinetic, and our theory agrees with the undulatory theory in assuming the existence of a medium capable of becoming a receptacle for two forms of energy. ”

“ We wind a simple ring of iron with coils; we establish the connections to the generator, and with wonder and delight we note the effects of strange forces which we bring into play, which allow us to transform, to transmit and direct energy at will. ”

“ Ere many generations pass, our machinery will be driven by a power obtainable at any point of the universe. This idea is not novel. Men have been led to it long ago by instinct or reason. It has been expressed in many ways, and in many places, in the history of old and new. We find it in the delightful myth of Antheus, who derives power from the earth; we find it among the subtile speculations of one of your splendid mathematicians, and in many hints and statements of thinkers of the present time. Throughout space there is energy. Is this energy static or kinetic? ”

“ In experimental and in physical work generally, it has been customary, in describing any simple process of energy transformation, to take account only of those energies or those forms of energy which play an active part in the process—the energy in its initial or applied form and the energy in its transformed or final form. ”

“ The term "energy" comprehends every state of a substance which constitutes a capacity for performing work. Quantities of energy are measured by the quantities of work which they constitute the means of performing.
"Actual energy" comprehends those kinds of capacity for performing work which consist in particular states of each part of a substance, how small soever; that is, in an absolute accident, such as heat, light, electric current, vis-viva. Actual energy is essentially positive. ”

“ My understanding of the doctrine is, that there are five chief powers or forces in Nature: one mechanical, or molar, the momentum of moving matter; the others molecular, or embodied in the molecules, also supposed in motion—these are, heat, light, chemical force, electricity. To these powers, which are unquestionable and distinct, it is usual to add vital force, of which, however, it is difficult to speak as a whole; but one member of our vital energies, the nerve-force, allied to electricity, fully deserves to rank in the correlation. ”

“ Mechanical or "work" energy is dissociated from any molecular action. On the other hand, the application of such forms of energy as heat or electrical energy to material leads to distinctly molecular or internal effects, in which some alteration in the constitution of the body affected may ensue. ”

“ According to the first principle of energetics, for the vital fact to be derived from the thermal fact, the heat must be preliminarily transformed into chemical energy, since chemical energy is necessarily an antecedent and generating form of vital energy. ”

“ Nature of the Science of Energetics. Energy, or the capacity to effect changes, is the common characteristic of the various states of matter to which the several branches of physics relate; if, then, there be general laws respecting energy, such laws must be applicable, mutatis mutandis, to every branch of physics, and must express a body of principles as to physical phenomena in general. ”

“ It has been already pointed out that, in the course of transformation in the field of an incepting influence, a material may attain a certain energy state in which it is no longer susceptible to that influence. ”

“ Molecules are composed of atoms, but the atoms, having no extension, are in reality nothing but the points of application of forces. Strictly speaking, not of forces but of energy, that same energy which is as much a unity and just as indestructible as matter. But matter, though one, has many different aspects, and the same is true of energy. Till recently only four forms of energy, convertible into one another, have been known to us: energies known as the dynamic, the thermal, the electric, and the chemic. ”

“ In no case do we find in Nature any body, or any energy system, to which energy may be applied in unlimited amount, but in every case, rigid energy limits are imposed, and, if these limits are exceeded, the whole energy character of the body or system is completely changed. ”

“ Energy Recognized by its Effects.—Like force, energy is invisible and we are aware of the forms only by the effects produced by it.
We recognize heat by warming, by expansion, by pressure.
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We recognize light by warming, by its affecting vision.
We recognize electrical energy by its heat, light, motion, or magnetic effect. We recognize mechanical energy by the motion that it produces. We recognize chemical energy by knowing that the source of energy does not belong to any of the foregoing.
A boy or girl is able to do considerable work. They therefore possess energy. ”

“ What the chemical ether is capable of effecting in a gentle manner, so to speak, in cooperation with the inertness-overcoming power of the warmth-ether, can be imitated physically only by an extraordinary concentration of external energy and the use of masses of material substance. ”

“ I have reached the conclusion that every physical phenomenon is due to the operation of energy transformations or energy transmissions embodied in material, and takes place under the action or influence of incepting energy fields. In any instance the precise nature of the phenomena is dependent on the peculiar form of energy actively engaged, on the nature of the material to which this energy is applied, and on the nature of the incepting field which influences the process. ”