Unit 2 Discussion: Energy, Gravity and Thermal Expansion

Electromagnetic induction This is the process where an electromotive force is produce across a conductor that is exposed to time varying magnetic fields How it is applied Electromagnetic induction is used in so many ways that is power transmission and also the power generation. There are other effects which can also result from the electromagnetic induction for example the eddy currents and sometimes in the transformer. Eddy currents This is the is the swirling current that is normally set up in a conductor as a result of the in response to a changing magnetic field. According to Lenz¹s law, the current normally swirls in such a way that creating a magnetic field which is opposing the change that occurs. Eddy current normally used during braking of the train this occurs when the metal wheels are exposed to a magnetic field which are from an electromagnet this will generate an eddy currents whithin the wheels then there will be magnetic interaction that occurs between the eddy currents and the applied field causing slowing down of ...

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THERMAL EXPANSION CONCEPT Most materials are subject to thermal expansion: a tendency to expand when heated, and to contract when cooled. For this reason, bridges are built with metal expansion joints, so that they can expand and contract without causing faults in the overall structure of the bridge. Other machines and structures likewise have built-in protection against the hazards of thermal expansion. But thermal expansion can also be advantageous, making possible the workings of thermometers and thermostats. HOW IT WORKS Molecular Translational Energy In scientific terms, heat is internal energy that flows from a system of relatively high temperature to one at a relatively low temperature. The internal energy itself, identified as thermal energy, is what people commonly mean when they say "heat." A form of kinetic energy due to the movement of molecules, thermal energy is sometimes called molecular translational energy. Temperature is defined as a measure of the average molecular translational energy in a system, and the greater the temperature change for most materials, as we shall see, the greater the amount of thermal expansion. Thus, all these aspects of "heat"—heat itself (in the scientific sense), as well as thermal energy, temperature, and thermal expansion—are ultimately affected by the motion of molecules in relation to one another. MOLECULAR MOTION AND NEWTONIAN PHYSICS. In general, the kinetic energy created by molecular motion can be understood within the framework of classical physics—that is, the paradigm associated with Sir Isaac Newton (1642-1727) and his laws of motion. Newton was the first to understand the physical force known as gravity, and he explained the behavior of objects within the context of gravitational force. Among the concepts essential to an understanding of Newtonian physics are the mass of an object, its rate of motion (whether in terms of velocity or acceleration), and the distance between objects. These, in turn, are all components central to an understanding of how molecules in relative motion generate thermal energy. The greater the momentum of an object—that is, the product of its mass multiplied by its rate of velocity—the greater the impact it has on another object with which it collides. The greater, also, is its kinetic energy, which is equal to one-half its mass multiplied by the square of its velocity. The mass of a molecule, of course, is very small, yet if all the molecules within an object are in relative motion—many of them colliding and, thus, transferring kinetic energy—this is bound to lead to a relatively large amount of thermal energy on the part of the larger object. MOLECULAR ATTRACTION AND PHASES OF MATTER. Yet, precisely because molecular mass is so small, gravitational force alone cannot explain the attraction between molecules. That attraction instead must be understood in terms of a second type of force—electromagnetism—discovered by Scottish physicist James Clerk Maxwell (1831-1879). The details of electromagnetic force are not important here; it is necessary only to know that all molecules possess some component of electrical charge. Since like charges repel and opposite charges attract, there is constant electromagnetic interaction between molecules, and this produces differing degrees of attraction. The greater the relative motion between molecules, generally speaking, the less their attraction toward one another. Indeed, these two aspects of a material—relative attraction and motion at the molecular level—determine whether that material can be classified as a solid, liquid, or gas. When molecules move slowly in relation to one another, they exert a strong attraction, and the material of which they are a part is usually classified as a solid. Molecules of liquid, on the other hand, move at moderate speeds, and therefore exert a moderate attraction. When molecules move at high speeds, they exert little or no attraction, and the material is known as a gas. Predicting Thermal Expansion COEFFICIENT OF LINEAR EXPANSION. A coefficient is a number that serves as a measure for some characteristic or property. It may also be a factor against which other values are multiplied to provide a desired result. For any type of material, it is possible to calculate the degree to which that material will expand or contract when exposed to changes in temperature. This is known, in general terms, as its coefficient of expansion, though, in fact, there are two varieties of expansion coefficient. The coefficient of linear expansion is a constant that governs the degree to which the length of a solid will change as a result of an alteration in temperature For any given substance, the coefficient of linear expansion is typically a number expressed in terms of 10−5/°C. In other words, the value of a particular solid's linear expansion coefficient is multiplied by 0.00001 per °C. (The °C in the denominator, shown in the equation below, simply "drops out" when the coefficient of linear expansion is multiplied by the change in temperature.) For quartz, the coefficient of linear expansion is 0.05. By contrast, iron, with a coefficient of 1.2, is 24 times more likely to expand or ...

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Electromagnetic induction This is the process where an electromotive force is produce across a conductor that is exposed to time varying magnetic fields How it is applied Electromagnetic induction is used in so many ways that is power transmission and also the power generation. There are other effects which can also result from the Electromagnetic induction for example the eddy currents and sometimes in the transformer. Eddy currents This is the will be the whirling current that is typically set up in a conductor as a consequence of the because of a changing attractive field. As per Lenz¹s law, the current ordinarily whirls in a manner that making an attractive field which is contradicting the change that happens. Whirlpool current ordinarily utilized amid braking of the train this happens when the metal wheels are presented to an attractive field which are from an electromagnet this will produce a swirl streams whithin the wheels then there will be attractive cooperation that happens between the vortex ebbs and flows and the connected field bringing on backing off of the wheel. An electric generator This gadget is utilized as a part of changing electrical energy into mechanical energy furthermore it can do the converse coming about to the mechanical energy. Inside the generator there is a wire which is ...

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