Physics I for Dummies Cheat Sheet - For Dummies

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1/5/12 Physics I For Dummies Cheat Sheet - For Dummies1/7 SheetPhsics I For DummiesFrom Physics I For Dummies, 2nd Edition by StevenHolznerPhysics involves a lot of calculations and problem solving. Having onhand the most frequently used physics equations and formulas helps youperform these tasks more efficiently and accurately. This Cheat Sheetalso includes a list physics constants that youll find useful in a broadrange of physics problems.Phsics Equations and FormulasPhysics is filled with equations and formulas that deal with angular motion,Carnot engines, fluids, forces, moments of inertia, linear motion, simpleharmonic motion, thermodynamics, and work and energy.Heres a list of some important physics formulas and equations to keep on hand arranged by topic so you dont have to go searching to find them.Angular motionEquations of angular motion are relevant wherever you have rotational motionsaround an axis. When the object has rotated through an angle of with anangular velocity of and an angular acceleration of , then you can use theseequations to tie these values together.You must use radians to measure the angle. Also, if you know that the distancefrom the axis is r, then you can work out the linear distance traveled, s, velocity, v,centripetal acceleration, ac, and force, Fc. When an object with moment ofinertia, I (the angular equivalent of mass), has an angular acceleration, , thenthere is a net torque .1/5/12 Physics I For Dummies Cheat Sheet - For Dummies2/7 engineA heat engine takes heat, Q

, from a high temperature source at temperature T

and moves it to a low temperature sink (temperature Tc) at a rate Qc and, in theprocess, does mechanical work, W. (This process can be reversed such thatwork can be performed to move the heat in the opposite direction a heatpump.) The amount of work performed in proportion to the amount of heatextracted from the heat source is the efficiency of the engine. A Carnot engine isreversible and has the maximum possible efficiency, given by the followingequations. The equivalent of efficiency for a heat pump is the coefficient ofperformance.Flid1/5/12 Physics I For Dummies Cheat Sheet - For Dummies3/7 volume, V, of fluid with mass, m, has density, . A force, F, over an area, A,gives rise to a pressure, P. The pressure of a fluid at a depth of h depends onthe density and the gravitational constant, g. Objects immersed in a fluid causinga mass of weight, Wwater displaced, give rise to an upward directed buoyancyforce, Fbuoyancy. Because of the conservation of mass, the volume flow rate of afluid moving with velocity, v, through a cross-sectional area, A, is constant.Bernoullis equation relates the pressure and speed of a fluid.FoceA mass, m, accelerates at a rate, a, due to a force, F, acting. Frictional forces,FF, are in proportion to the normal force between the materials, FN, with acoefficient of friction, . Two masses, m1 and m2, separated by a distance, r,attract each other with a gravitational force, given by the following equations, inproportion to the gravitational constant G:Momen of ineiaThe rotational equivalent of mass is inertia, I, which depends on how an objectsmass is distributed through space. The moments of inertia for various shapesare shown here:Disk rotating around its center:Hollow cylinder rotating around its center: I = mr

Hollow sphere rotating an axis through its center:1/5/12 Physics I For Dummies Cheat Sheet - For Dummies4/7 rotating around its center: I = mr

Point mass rotating at radius r: I = mr

Rectangle rotating around an axis along one edge where the other edge is oflength r:Rectangle rotating around an axis parallel to one edge and passing throughthe center, where the length of the other edge is r:Rod rotating around an axis perpendicular to it and through its center:Rod rotating around an axis perpendicular to it and through one end:Solid cylinder, rotating around an axis along its center line:The kinetic energy of a rotating body, with moment of inertia, I, and angularvelocity, :The angular momentum of a rotating body with moment of inertia, I, andangular velocity, :Linear moionWhen an object at position x moves with velocity, v, and acceleration, a, resultingin displacement, s, each of these components is related by the followingequations:1/5/12 Physics I For Dummies Cheat Sheet - For Dummies5/7 harmonic motionParticular kinds of force result in periodic motion, where the object repeats itsmotion with a period, T, having an angular frequency, , and amplitude, A. Oneexample of such a force is provided by a spring with spring constant, k. Theposition, x, velocity, v, and acceleration, a, of an object undergoing simpleharmonic motion can be expressed as sines and cosines.ThermodnamicsThe random vibrational and rotational motions of the molecules that make up anobject of substance have energy; this energy is called thermal energy. Whenthermal energy moves from one place to another, its called heat, Q. When anobject receives an amount of heat, its temperature, T, rises.Kelvin (K), Celsius (C), and Fahrenheit (F) are temperature scales. You can usethese formulas to convert from one temperature scale to another:The heat required to cause a change in temperature of a mass, m, increaseswith a constant of proportionality, c, called the specific heat capacity. In a bar ofmaterial with a cross-sectional area A, length L, and a temperature differenceacross the ends of T, there is a heat flow over a time, t, given by theseformulas:1/5/12 Physics I For Dummies Cheat Sheet - For Dummies6/7 pressure, P, and volume, V, of n moles of an ideal gas at temperature T isgiven by this formula, where R is the gas constant:In an ideal gas, the average energy of each molecule KEavg, is in proportion tothe temperature, with the Boltzman constant k:Work and energWhen a force, F, moves an object through a distance, s, which is at an angle of,then work, W, is done. Momentum, p, is the product of mass, m, and velocity,v. The energy that an object has on account of its motion is called KE.A List of Phsics ConstantsPhysics constants are physical quantities with fixed numerical values. Thefollowing list contains the most common physics constants, including Avogadrosnumber, Boltzmanns constant, the mass of electron, the mass of a proton, thespeed of light, the gravitational constant, and the gas constant.Avogadros number:Boltzmanns constant:Mass of electron:1/5/12 Physics I For Dummies Cheat Sheet - For Dummies7/7 of proton:Speed of light:Gravitational constant:Gas constant:bl og comments powered by DISQUSCopyright 2012 & Trademark by John Wiley & Sons, Inc. All rights reserved.M Subscribe by email RSSShoing 0 commentsLieLoginAdd Ne CommentSort b newest first