Physics
Theoretical Energy
Theoretical energy refers to the energy associated with an object or system based on theoretical principles and calculations rather than direct measurements. It is often used in theoretical physics to make predictions and understand the behavior of physical systems. Theoretical energy can encompass various forms of energy, such as potential energy, kinetic energy, and other types of energy within the framework of theoretical models.
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10 Key excerpts on "Theoretical Energy"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
In particle physics, this inequality permits a qualitative understanding of virtual particles which carry momentum, exchange by which and with real particles, is responsible for the creation of all known fundamental forces (more accurately known as fundamental interactions). Virtual photons (which are simply lowest quantum mechanical energy state of photons) are also responsible for electrostatic interaction between electric charges (which results in Coulomb law), for spontaneous radiative decay of exited atomic and nuclear states, for the Casimir force, for van der Waals bond forces and some other observable phenomena. Applications of the concept of energy Energy is subject to a strict global conservation law; that is, whenever one measures (or calculates) the total energy of a system of particles whose interactions do not depend explicitly on time, it is found that the total energy of the system always remains constant. • The total energy of a system can be subdivided and classified in various ways. For example, it is sometimes convenient to distinguish potential energy (which is a function of coordinates only) from kinetic energy (which is a function of coordinate time derivatives only). It may also be convenient to distinguish gravitational energy, electric energy, thermal energy, and other forms. These classifications overlap; for instance, thermal energy usually consists partly of kinetic and partly of potential energy. • The transfer of energy can take various forms; familiar examples include work, heat flow, and advection, as discussed below. ________________________ WORLD TECHNOLOGIES ________________________ • The word energy is also used outside of physics in many ways, which can lead to ambiguity and inconsistency. The vernacular terminology is not consistent with technical terminology.
eBook - ePub- Justin P. Lomont, Ian C. Stewart(Authors)
- 2013(Publication Date)
- Visible Ink Press(Publisher)
PHYSICAL AND THEORETICAL CHEMISTRY
ENERGY IS EVERYTHING
What is physical chemistry?Physical chemistry is a branch of chemistry primarily concerned with developing a better understanding of the fundamental principles that govern chemical processes. It is an empirical science, meaning that it is based on experimental observations, though it is probably the most closely linked experimental branch of chemistry to developing new theories in chemistry. As the name implies, physical chemistry is intrinsically concerned with topics in physics that are also relevant to the study of chemistry.What is energy?In chemistry, energy serves as the “currency” for making or breaking chemical bonds and moving molecules (or matter) from one place to another.What is potential energy?Potential energy describes all of the nonkinetic energy associated with an object. This energy can be the energy stored in chemical bonds, in a compressed spring, or in a variety of other ways. Another example is gravitational potential energy, like that associated with a ball sitting at the top of a hill. Since there are many types of potential energy, there isn’t a single equation that describes them all. Since the value we assign to potential energy is always inherently described relative to some choice of a reference value, we can only actually measure changes in potential energy in a meaningful way. A closed system can exchange potential energy for kinetic and vice versa, but the total energy must always remain constant. This is stated in the First Law of Thermodynamics, which we’ll get to soon.What is kinetic energy?Kinetic energy is the type of energy associated with the movement of an object. Faster-moving objects have more kinetic energy, and the kinetic energy of an object is related to its mass, m, and velocity, v, by the equation:
eBook - ePub- E. Atlee Jackson(Author)
- 2012(Publication Date)
- Dover Publications(Publisher)
models (simplified pictures) of atoms, molecules, gases, and solids will illustrate the various types of interactions between particles. Finally, we shall consider some of the important modifications of these classical models that are required by quantum mechanics.2. KINETIC AND POTENTIAL ENERGY
To begin with, let us consider a particle moving in space as it is described in classical mechanics. The position of the particle r (t ) = x (t )i + y (t )j + z (t )k [where (i, j, k ) are the unit vectors in the (x , y , z ) directions] generally varies in time and has a velocityIf the particle has a mass m, it is said to have a kinetic energy (sometimes called the translational energy )(1)If a force F acts on the particle, its velocity will change according to Newton’s law(2)If no force acts on the particle, then it follows from Equation (2) that v is independent of the time, and consequently the kinetic energy is also a constant. We can also see this from the fact that(3)which vanishes if F vanishes.Now the force that acts on the particle generally depends on the position of the particle r and sometimes also on the velocity (e.g., frictional forces, or the force on a charged particle moving in a magnetic field). If the force depends only on r and if it can be expressed in terms of the gradient of some function Φ
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Library Press(Publisher)
Internal Energy In thermodynamics, the internal energy is the total energy contained by a thermodynamic system. It is the energy necessary to create the system, but excludes the energy to displace the system's surroundings, any energy associated with a move as a whole, or due to external force fields. Internal energy has two major components, kinetic energy and potential energy. The kinetic energy is due to the motion of the system's particles (translations, rotations, vibrations), and the potential energy is associated with the static constituents of matter, static electric energy of atoms within molecules or crystals, the static energy of chemical bonds. The internal energy of a system can be changed by heating the system or by doing work on it; the first law of thermodynamics states that the increase in internal energy is equal to the total heat added and work done. If the system is isolated, its internal energy cannot change. For practical considerations in thermodynamics or engineering it is rarely necessary, nor convenient, to consider all energies belonging to the total intrinsic energy of a sample system, such as the energy given by the equivalence of mass. Typically, descriptions only include components relevant to the system under study. Thermodynamics is chiefly concerned only with changes of the internal energy. The internal energy is a state function of a system, because its value depends only on the current state of the system and not on the path taken or process undergone to arrive at this state. It is an extensive quantity. The SI unit of energy is the joule. Sometimes physicists define a corresponding intensive thermodynamic property called specific internal energy , which is internal energy per a unit of mass of the system in question. As such, the SI unit of specific internal energy is J/kg. If intensive internal energy is expressed per amount of substance, then it is referred to as molar internal energy and the unit is J/mol.
- Allan D. Kraus, James R. Welty, Abdul Aziz(Authors)
- 2011(Publication Date)
- CRC Press(Publisher)
3 Energy and the First Law of Thermodynamics Chapter Objectives • To describe the forms of energy and to define what is meant by kinetic, potential, internal, and total energy. • To define work and to show that it is not a property but a path function that depends on the path between two state points. • To define heat transfer and to show that it is not a property but a path function that depends on the path between two state points. • To present the concept of conservation of energy and to link all of the energy quantities considered into the first law of thermodynamics. • To consider thermodynamic cycles. • To develop the ideal gas model. • To consider enthalpy and specific heats for ideal gases. • To present the equations that govern three of the five fundamental processes of the ideal gas. 3.1 Introduction Energy may be defined as the capability or capacity to produce work. It is contained in all matter and while it exists in many different forms, these forms, however, are well defined. Because matter is anything that possesses mass and occupies space , energy is related to mass. Moreover, we may note that Einstein’s theory of relativity suggests that mass, m , may be converted to energy, E , (and energy may be converted to mass) via E = mc 2 where c = 2 . 9997 × 10 8 m/s is the speed of light. However, for all energy-mass interactions other than nuclear reactions, the amount of mass converted to energy is extremely small and can be neglected. Thus, in this study, we state the conservation of mass principle that is often quoted in subsequent discussions as Mass can neither be created nor destroyed and its composition cannot be altered from one form to another unless it undergoes a chemical change. 37 38 Introduction to Thermal and Fluid Engineering FORMS OF ENERGY Kinetic Energy is the energy that a body possesses by virtue of its motion. Potential Energy is the energy that a body possesses by virtue of its position.
eBook - PDFThermodynamics
Fundamentals and Engineering Applications
- William C. Reynolds, Piero Colonna(Authors)
- 2018(Publication Date)
- Cambridge University Press(Publisher)
2 Energy CONTENTS 2.1 Concept of Energy 16 2.2 Microscopic Energy Modes 17 2.3 Internal Energy 18 2.4 Total Energy 18 2.5 Energy Transfer as Work 18 2.6 Energy Transfer as Heat 20 2.7 Energy Balances 22 2.8 Examples 23 Exercises 28 In the first chapter we reviewed the concept of energy as it arises in mechanical systems. We interpreted work as a transfer of energy and used this idea to develop expressions for kinetic and potential energy. These were special instances of the general concept of energy, which is perhaps the most fundamental concept in all of science. In thermodynamics, another relevant mode of energy transfer is heat. Once all these concepts are clear, they can be used together with the first law to analyze and design an infinite variety of systems and devices, which are at the foundation of current and future societies. 2.1 Concept of Energy The Energy Hypothesis The ideas inherent in the general concept of energy are encapsulated in what we call the Energy Hypothesis : Matter can be treated as having a property, called energy , that is an extensive, conserved scalar mea-suring its ability to cause change; work is a transfer of energy. The terms used above are very important: ● extensive means that the energy of a system is the sum of the energies of its parts; ● conserved means that the total amount of energy in an isolated system does not change; ● scalar means that energy is a quantity without directional (vector) character; ● work is a transfer of energy; it provides the key to the quantitative evaluation of the energy contained by matter. In Section 1.4 we used these ideas to obtain expres-sions for the kinetic and potential energy of matter. 2.2 Microscopic Energy Modes 17 Other energy forms are evaluated in the same way. Since the energy hypothesis is itself used in the evaluation and measurement of the energy of mat-ter, it is not possible to test the hypothesis of energy conservation by experimental measurements of energy.
eBook - PDF- Anco S. Blazev(Author)
- 2021(Publication Date)
- River Publishers(Publisher)
ENERGY APPLICATIONS Energy, in all its forms and variations, is widely used in the sciences. For example: • In physics , energy is considered a quantity that ex -ists, but is indirectly observed (or invisible and im -measurable in its purest form. It comes to life, and is measurable when its other components (force and distance) are considered. In that case energy becomes work, and can be measured as a physical entity. The work then could be observed, measured and expressed as heat, electric power, mass, speed, etc. variables. For example, photons traveling from the sun through space have potential energy stored, which upon impact onto a solar panel is released and converted into heat (heating the panels) and elec -tricity, which can be extracted and used. • In chemistry , energy is an attribute of a substance as a consequence of its atomic, molecular or aggre -gate structure. Since a chemical transformation is accompanied by a change in one or more of these kinds of structure, it is invariably accompanied by an increase or decrease of energy of the substances involved. Some energy is transferred between the surroundings and the reactants of the reaction in the form of heat or light; thus the products of a reaction may have more or less energy than the reactants. Chemical reactions are invariably not possi -ble unless the reactants overcome an energy barrier known as the activation energy. The speed of a chemical reaction (at given temperature T) is relat -ed to the activation energy E, by the Boltzmann’s population factor e−E/kT, which represents the probability of a molecule to have energy greater than or equal to E at the given temperature T. This exponential dependence of a reaction rate on tem-perature is known as the Arrhenius equation. The activation energy necessary for a chemical reaction can be in the form of thermal energy. • In biology , energy is an attribute of all biological systems from the biosphere to the smallest living organism.
- John Reisel(Author)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
2.2 TYPES OF ENERGY Just as Julius Caesar said that all of Gaul is divided into three parts, for our purposes we can say that all of the energy of a substance is divided into three parts: internal energy, kinetic energy, and potential energy. Although each of these forms plays a prominent role in certain applications, they are usually not equally important. As we will see later, and as illustrated in Figure 2.1, we can neglect various forms of energy in a system depending on the application; this will simplify our thermodynamic problems. FIGURE 2.1 The total energy of a system is the combination of the system’s internal energy, kinetic energy, and potential energy. Internal Energy Kinetic Energy Total Energy Potential Energy Copyright 2022 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 37 2.2 Types of Energy 2.2.1 Potential Energy Potential energy is the energy in a system resulting from the system being in a gravitational field, and it is due to the mass of the system being higher than some reference point. There is the potential for the substance to produce an effect, and this potential will be unleashed if the sub- stance is allowed to fall under the effect of gravity toward the reference point—typically the ground or floor. A sub- stance that does not change its height during a process retains its initial potential energy. For example, as shown in Figure 2.2, a ball that is being held out a window has potential energy, but no changes are produced until the ball is released. Until the ball is released, the potential energy contained in the ball is essentially useless.
No longer available |Learn more- Irving Granet, Maurice Bluestein(Authors)
- 2014(Publication Date)
- CRC Press(Publisher)
In addition, it pos-sesses energy due to the internal attractive and repulsive forces between particles. These forces become the mechanism for energy storage whenever particles become separated, such as when a liquid evaporates or the body is subjected to a deformation by an external energy source. Also, energy may be stored in the rotation and vibration of the molecules. Additional amounts of energy are involved with the electron configuration within the atoms and with the nuclear particles. The energy from all such sources is called the inter-nal energy of the body and is designated by the symbol U . Per unit mass ( m ), the specific internal energy is denoted by the symbol u , where mu = U . Thus, mu U = (2.1) or u U m = (2.2) 64 Thermodynamics and Heat Power From a practical standpoint, the measurement of the absolute internal energy of a system in a given state presents an insurmountable problem and is not essential to our study of thermodynamics. We are concerned with changes in internal energy, and the arbitrary datum for the zero of internal energy will not enter into these problems. Just as it is possible to distinguish the various forms of energy, such as work and heat, in a mechanical system, it is equally possible to distinguish the various forms of energy associated with electrical, chemical, and other systems. For the purpose of this book, these forms of energy, work, and heat are not considered. Students are cautioned that if a system includes any forms of energy other than mechanical, these items must be included. For example, the energy that is dissipated in a resistor as heat when a current flows through it must be taken into account when all the energies of an electrical system are being considered. 2.5 Potential Energy Let us consider the following problem, illustrated in Figure 2.3, where a body of mass m is in a locality in which the local gravitational field is constant and equal to g .
- S. Bobby Rauf(Author)
- 2021(Publication Date)
- River Publishers(Publisher)
Law of Conservation of Energy The law of conservation of energy states that energy can be con-verted from one form to another but cannot be created or destroyed . This can be expressed, mathematically, as: 8 Thermodynamics Made Simple for Energy Engineers ∑ E = ∑ Energy = Constant Table 1-3. Rankin Temperature Conversion Formulas Table 1-4. Kelvin Temperature Conversion Factors FORMS OF ENERGY IN MECHANICAL AND THERMODYNAMIC SYSTEMS Potential Energy Potential energy is defned as energy possessed by an object by vir-tue of its height or elevation. Potential energy can be defned, mathemati-cally, as follows: E potential = m.g.h, {SI Units} Eq. 1-8 E potential = m.(g/g c ).h, US Units} Eq. 1-8a When the change in potential energy is achieved through performance of work, W : W = Δ E potential Eq. 1-9 9 Introduction to Energy, Heat, and Thermodynamics Kinetic Energy Kinetic energy is defned as energy possessed by an object by virtue of its motion. Kinetic energy can be defned, mathematically, as follows: E kinetic = ½.m.v 2 {SI Units} Eq. 1-10 E kinetic = ½. (m/g c ). v 2 {US Units} Eq. 1-10a Where, m = mass of the object in motion v = velocity of the object in motion g c = 32 lbm-ft/lbf-s 2 When the change in kinetic energy is achieved through performance of work, W : W = Δ E kinetic Eq. 1-11 Energy Stored in a Spring 2 Potential energy can be stored in a spring—or in any elastic object— by compression or extension of the spring. Potential energy stored in a spring can be expressed, mathematically, as follows: E spring = ½.k.x 2 Eq. 1-12 And, W spring = Δ E spring Eq. 1-13 Where, k = The spring constant x = The contraction or expansion of the spring 2 Note: In steel beam systems, beams act as springs, when loaded, to a certain degree. The defection of a beam would represent the “ x ,” in Eq. 1-11. Pressure Energy Energy stored in a system in form of pressure is referred to as pres- 10 Thermodynamics Made Simple for Energy Engineers sure energy.
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