Physics
Materials Energy
Materials energy refers to the energy associated with the atomic and molecular structure of materials. It encompasses the potential and kinetic energy stored within the bonds and interactions between atoms and molecules in a material. Understanding materials energy is crucial in various fields such as materials science, engineering, and physics, as it influences the behavior and properties of materials.
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3 Key excerpts on "Materials Energy"
eBook - PDF- Richard L. Myers(Author)
- 2005(Publication Date)
- Greenwood(Publisher)
The arrangement and recon- figuration of atomic nuclei is the source of nuclear potential energy. Elastic potential energy results from the deformation on an object. For example, when a spring is com- pressed or stretched, energy is stored in the spring as elastic potential energy. Kinetic energy is the energy of motion. Anything that moves possesses kinetic energy. Translational kinetic energy is equal to one-half times the product of mass and the magnitude of velocity squared: translational kinetic energy = l/2(mv 2 ) Rotational kinetic energy is equal to one-half times the product of the moment of inertial and the magnitude of rotational velocity squared: rotational kinetic energy = \/2(IOJ 2 ) The fact that translational kinetic energy is related to the square of the velocity has con- sequences during storms when wind speeds increase significantly above normal condi- tions. A 50 mph wind compared to a 10 mph wind has 25 times the kinetic energy, while hurricane winds of 100 mph would have 100 times the kinetic energy of a 10 mph wind. An object resting on the ground has zero kinetic energy and zero gravitational potential energy with respect to the Earth's surface, but it would be wrong to assume it possesses no energy. The object is made of atoms, and each atom contains electrons revolving around an atomic nucleus. By virtue of their trans- lational, rotational, and vibrational motion, atoms possess kinetic energy. Matter also pos- sesses chemical potential energy stored within chemical bonds, as mentioned previously. The internal energy is the sum total of the kinetic and potential energy possessed by the atoms and molecules comprising matter. Work Inherent in the definition of energy are the terms work and heat. Work and heat are transfer properties and can be considered processes that transfer energy across a sys- tem's boundary. Work can be transferred to the system across the system boundary from the surroundings or from the system to the surroundings.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
That is, energy is conserved because the laws of physics do not distinguish between different instants of time. Energy in various contexts The concept of energy and its transformations is useful in explaining and predicting most natural phenomena. The direction of transformations in energy (what kind of energy is transformed to what other kind) is often described by entropy (equal energy spread among all available degrees of freedom) considerations, as in practice all energy transformations are permitted on a small scale, but certain larger transformations are not permitted because it is statistically unlikely that energy or matter will randomly move into more concentrated forms or smaller spaces. The concept of energy is widespread in all sciences. • In the context of chemistry, energy is an attribute of a substance as a consequence of its atomic, molecular or aggregate 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. A reaction is said to be exergonic if the final state is lower on the energy scale than the initial state; in the case of endergonic reactions the situation is the reverse. Chemical reactions are invariably not possible unless the reactants surmount an energy barrier known as the activation energy. The speed of a chemical reaction (at given temperature T ) is related to the activation energy E , by the Boltzmann's population factor e − E / kT – that is the probability of molecule to have energy greater than or equal to E at the given temperature T . This exponential dependence of a reaction rate on temperature is known as the Arrhenius equation.
eBook - PDFIntroductory Chemistry
An Active Learning Approach
- Mark Cracolice, Edward Peters, Mark Cracolice(Authors)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 44 Chapter 2 Matter and Energy closer to one another within a molecule or when unlike-charged particles are moved apart, the potential energy of the molecule is increased. Chemical systems tend to change in a way that reduces their total energy. For example, a fuel will burn on its own, transferring energy to the surroundings, after the burning reaction is initiated with a spark. The chemical energy within molecules comes largely from the arrangement of minuscule charged particles within the mole- cules. Reduction of the energy in a chemical system to the smallest amount possible is one of the driving forces that causes chemical changes to occur. You will see this mentioned again from time to time in this textbook. Target Check 2.7 a) Is the process of boiling water exothermic or endothermic with respect to the water? b) A charged object is moved closer to another object that has the same charge. The energy of the system changes. Is it a change in kinetic energy or potential energy? Is the energy change an increase or a decrease? Learn It Now! There are three pairs of terms in Section 2.9 that represent concepts that you need to understand: reactant and product; exothermic and endothermic; and kinetic and potential energy. Be sure that you understand each individual term as well as how it is related to the term it is paired with. 2.10 Conservation Laws and Chemical Change The Law of Conservation of Mass and Energy In 1905, Albert Einstein (Figure 2.27) published a paper in a scientific journal (see the discussion about communication in science in Section 1.2) that proposed that a fundamental principle of nature is the sameness between energy and mass. This mass-energy equivalence may be expressed as the equation Figure 2.27 Albert Einstein (1879–1955) is possibly the most well-recognized scientist in history.
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