Forms of Energy

Energy is usually defined as the capacity to do work or transfer heat All forms of energy are either kinetic or potential. Kinetic energy is the energy that results from motion. It is calculated with the equation 

If the charges Qi and Q2 are opposite (i.e., one positive and one negative), the result is a negative value for E, which indicates attraction. Like charges (i.e., both positive or both negative) result in a positive value for E, indicating repulsion. 

The energy within a system can be transformed from one form to another. 

Name the three common forms that energy is divided into. See if you can define each 

Energy is classified according to three specific forms (1) The macroscopic Idnetic energy, Ek is the energy associated with the bulk (macroscopic) motion of the system as a whole. For example, an object of mass m moving at velocity V has a kinetic energy 

Energy is not an absolute quantity but rather is only defined relative to a reference state, so we must be careful to identify the particular reference state that we are using. As you read this text, what is your kinetic energy (assuming you are not riding the bus)  

If you answer zero, you are correct in the context of a weU-defined reference state, the Earth. However, if instead we had considered the sun to be the reference state, the answer would be quite different. The Earth is in motion with a velocity of 30,000 m/s around the sun, and your kinetic energy is on the order of 10 J In the case of kinetic and potential energy, we usually define Ek (i e., V ) as zero when there is no motion relative to the Earth and Ep (i.e., z) as zero at the surface of the Earth. In fact, these reference states are so obvious they are sometimes implicitly assumed. In this text, we will be care-frd to identify references states explicitly. This effort wiU become useful in the case of U, where there is more than one convenient reference state. What is the reference state used for U in the steam tables  

Most of the energy we encounter can be placed into two broad categories potential energy and kinetic energy. Potential energy is associated with the relative position of an object. For example, a roller coaster gains potential energy as it is 

As implied above, energy has many forms, and they are interconvertible, subject to some restrictions (the restrictions apply only to the direction of conversion). Let us consider a 1-kg ball of steel. What forms of energy can it possess  

If the steel is at a temperature of 20 C, you can hold it in your hand. If it is at a temperature of 200°C, you cannot hold it in your hand very long. Clearly, the ball at 200°C produces effects which the ball at 20°C cannot. Yet, if we measure the mass of the ball, it is the same at 20°C as it is at 200°C (within the precision of current measuring techniques). If we could label the atoms when the ball was at 20 C and take a census of them when the ball was at 200°C, we would find exactly the same atoms present. Therefore, the difference between what the ball will do at 20°C and what it will do at 200 C is not dependent on changing the mass or identity of the matter present. Something else obviously is involved. For now we say that a body which is hot possesses more internal energy than the same body does when cold. 

Now suppose that instead of an iron ball we have a balloon which contains a mixture of gasoline and oxygen with a tbtal mass of 1 kg at 20°C. Now we can introduce a small spark, and the contents of the balloon become very hot (explosively so). After a moment the contents will be much hotter than at the start, and they will have a different chemical composition instead 

an approximate rule (with exceptions internal energy is a measure of hotness plus the abi 

Salad oil, egg yolks, and vinegar do not form a homogeneous mixture. If they are gently shaken together and then allowed to settle, they will separate cleanly. If, however, they are beaten very vigorously, to break up the oil into small droplets, then they will form a stable system called mayonnaise. Under normal conditions mayonnaise will not separate back into salad oil, egg yolks, and vinegar it is an emulsion. Emulsions possess properties that their unmixed constituents do not. These are due to the surface energy of all the microscopic droplets which make up an emulsion. 

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Table 6.1 gives the mathematical forms of energy terms often used in popular force fields. The constants may vary from one force field to another according to the designer s choice of unit system, zero of energy, and fitting procedure. 

Thermodynamics is the study of thermal, electrical, chemical, and mechanical forms of energy. The study of thermodynamics crosses many disciplines, including physics, engineering, and chemistry. Of the various branches of thermodynamics. 

Figure 3 provides a comparison of the energy costs in the U.S. residential market for natural gas, electricity, or No. 2 fuel oil (1). The prices of all three forms of energy to residential users have increased for the period shown. Electrical energy has had the largest doUar increase. 

The term pressure drop usually refers to the pressure loss that is not recoverable in the circuit, and it is lost energy that is dissipated into the fluid stream in the form of heat energy. The pressure drop in a flow circuit is associated with various forms of energy dissipation owing to friction, change in flow area, flow turning, and others ... 

Ferromanganese is produced iu blast fiimaces and electric smelting fiimaces. Economics usually determine which smelting process is chosen for ferromanganese. Both methods require about the same amount of coke for reduction to metal, but iu the case of the blast fiimace, the thermal energy required for the smelting process is suppHed by the combustion of additional coke, which iu most countries is a more expensive form of energy than electricity. 

In an energy-conscious world, SI provides a direct relationship among mechanical, electric, chemical, thermodynamic, molecular, and solar forms of energy. AH power ratings are given in watts. 

There exists a form of energy, known as internal energy, which for. systems at internal equilibrium is an intrinsic propei ty of the. system, functionally related to its characteristic coordinates. 

When applied to closed (constant-mass) systems for which the only form of energy that changes is the internal energy, the first law of thermodynamics is expressed mathematically as... 

The most common form of energy deposition used for planar shock wave research has been electrical resistance heating of a metal foil which vaporizes, driving a flyer plate to a high velocity before it impacts a specimen. In a hybrid system incorporation both resistance vaporization and an electromagnetic push, velocities to 18 km/s are reported for kapton flyer plates which are... 

THERMODYNAMICS The Study of laws that govern the conversion of one form of energy to another. 

But it was not until J. P. Joule published a definitive paper in 1847 that the ealorie idea was abandoned. Joule eonelusively showed that heat was a form of energy. As a result of the experiments of Rumford, Joule, and others, it was demonstrated (explieitly stated by Helmholtz in 1847), that the various forms of energy ean be transformed one into another. 

When heat is transformed into any other form of energy, or when other forms of energy are transformed into heat, the total amount of energy (heat plus other forms) in the system is constant. This is known as the first law of thermodynamics, i.e., the eonservation of energy. To express it another way it is m no way possible either by meehanieal, thermal, ehemical, or other means, to obtain a perpetual motion maehine i.e., one that ereates its own energy. 

Therefore, when a noise is to be reduced, the sound energy must be con verted into another form of energy, such as kinetic energy of a medium or heat. 

The First Law Heat, Work, and Other Forms of Energy... 

Cogeneration is the production of two useful forms of energy in a single energy conversion process. For example, a gas turbine may produce both rotational energy for an electric generator and heat for a building. 

Efficiency is a practical measure of the performance of a converter efficiency is equal to the desired form of energy divided by the total energy converted. If the light converted 100 joules of energy into 10... 

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