kinem1 - Physics 53 Kinematics 1 A child of ve can...

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Physics 53 Kinematics 1 A child of Fve can understand this. Send someone to fetch a child of Fve. — Groucho Marx Introduction and overview. In constructing the description of nature we call science it has been found useful to assume that things we observe directly with our senses are actually the combined effects of the behavior of a very large number of objects so small as to be invisible to us. That is, our senses are able to convey to us the gross aspects of things around us, but those aspects are in reality determined by the unobserved behavior of constituent microscopic objects. This “reductionist” assumption about the nature of matter was Frst introduced largely as a convenient model for mathematical analysis, without any direct evidence for the existence of the small objects. But since the late 1800’s we have come to realize that matter really does consist of such things, in the form of molecules, atoms, electrons, neutrons and protons, to which we give the generic name particles . ±or the purposes of this course we assume only that the particles possess mass, and that they are small enough (by our standards) that, as an approximation, we can say they occupy a single point in space. In the second course other properties they possess, especially their electric and magnetic properties, will be important to us. This course begins with a description of the behavior of a single particle. At Frst we are concerned with the appropriate quantitative (i.e., mathematical) description of where the particle is located in space at a particular time , and how that location changes with time as the particle moves . This study is called kinematics of a particle . We then discuss the “in²uences” that “cause” it to move in particular ways. This leads to dynamics of a particle , for which the relevant general principles are Newton’s laws of motion . In²uences affecting motion are called interaction forces ; we give simple mathematical descriptions of several that occur in everyday situations. Aspects of the state of motion itself are expressed through the important concepts of momentum and energy . Having established the rules for motion of a single particle, we show by mathematical argument how the behavior of systems of more than one particle (perhaps very many) can be accounted for in terms of these same rules. This leads to the discovery of conservation laws of mass, momentum, energy, and angular momentum, specifying conditions under which the totals of those quantities for the whole system remain constant in time, no matter how complicated the motions of the individual particles. PHY 53 1 Kinematics 1
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The rest of the course describes applications of these general principles. First we examine the behavior of a rigid body , a system of particles tightly bound together. Then we look in some detail at the important interaction called gravity , which Newton showed could account for the motion of satellites — including the planets and their
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This note was uploaded on 10/19/2011 for the course PHYSICS 53L taught by Professor Mueller during the Spring '07 term at Duke.

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kinem1 - Physics 53 Kinematics 1 A child of ve can...

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