6 Work And Energy

6 Work And Energy - Chapter 6 Work and Energy Chapter 6...

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Chapter 6 Work and Energy 82 Chapter 6 WORK AND ENERGY PREVIEW Work is the scalar product of the force acting on an object and the displacement through which it acts. When work is done on or by a system, the energy of that system is always changed. If work is done slowly, we say that the power level is low. If work is done quickly, the power level is high. Kinetic energy is the energy an object has because of its motion, and potential energy is the energy an object has because of its location or configuration. If the energy of a system remains constant throughout a process, we say that energy is conserved . The content contained in all sections of chapter 6 of the textbook is included on the AP Physics B exam. QUICK REFERENCE Important Terms conservative force a force which does work on an object which is independent of the path taken by the object between its starting point and its ending point conserved properties any properties which remain constant during a process energy the non-material quantity which is the ability to do work on a system joule the unit for energy equal to one Newton-meter kinetic energy the energy a mass has by virtue of its motion law of conservation of energy the total energy of a system remains constant during a process mechanical energy the sum of the potential and kinetic energies in a system potential energy the energy an object has because of its position power the rate at which work is done or energy is dissipated watt the SI unit for power equal to one joule of energy per second work the scalar product of force and displacement
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Chapter 6 Work and Energy 83 Equations and Symbols       v F P t W P KE PE KE PE h h mg PE W mgh PE mv mv KE KE W mv KE s F W f f f g g f f cos 2 1 2 1 2 1 cos 0 0 0 2 0 2 0 2 v F s F where W = work F = force s = displacement F • s = scalar product of force and displacement KE = kinetic energy v = velocity or speed m = mass PE = potential energy (denoted as U on the AP Physics exam) g = acceleration due to gravity h = height above some reference point P = power t = time Ten Homework Problems Chapter 6 Problems 8, 10, 16, 20, 61, 64, 67, 73, 77, 78 DISCUSSION OF SELECTED SECTIONS 6.1 Work Done by a Constant Force As you know by now, there are many words in physics that have meanings which are well-defined but not necessarily used in the way they are normally used outside of the context of a physics course, and work is certainly one of these words. In physics, work is defined as the scalar product of force and displacement, that is, W = F·s = Fscos where is the angle between the applied force and the displacement. Here, the force and displacement vectors are multiplied together in such a way that the product yields a scalar. Thus, work is not a vector, and has no direction associated with it. Since work is the product of force and displacement, it has units of newton-meters, or joules (J). A joule
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This note was uploaded on 03/30/2012 for the course PHYSICS 201 taught by Professor Rollino during the Fall '11 term at Rutgers.

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6 Work And Energy - Chapter 6 Work and Energy Chapter 6...

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