Instead of one positive charge outside a conductingwire, as was discussed in Section 2.14 and shown inFigure 2.34, consider a second conducting wire parallelto the fi rst one. Both wires have positive and negativecharges, and the wires are electrically neutral.Assume that in both wires the positive charges travelto the right and negative charges to the left. (a) Consideran inertial frame moving with the negativecharges of wire 1. Show that the second wire is attractedto the fi rst wire in this frame. (b) Now consideran inertial frame moving with the positivecharges of the second wire. Show that the fi rst wire isattracted to the second. (c) Use this argument to showthat electrical and magnetic forces are relative?
Elementary Classical Physics I Chapter 6: Energy and Work 6.1 Energy Energy ability to do work Scalar quantity Measured in Joules CONSERVED Energy Conservationenergy cannot be created nor destroyed; only transferred Types of energy 1) Potential 2) Kinetic 3) Internal a) Intermolecular motion 4) Electromagnetic 6.2 Work Work amount of energy transferred to or from a substance by means of an external force acting upon it over a distance Energy transferred to a system +Work Energy taken from a system Work Work and Force Configurations 1) 1D: Force and direction are collinear; Force is constant a) W=F Δxx b) Joules= N*m 2) 2D:Force and direction are coplanar; Force is constant a) Angle dot product i) W= |F|[d]cosθ ii) is the angle between the two vectors 3) 3D:Force and direction are 3D; Force is constant a) W=F *xxF *yy *zz 6.3 Varying Force 4) 1D:Force and direction are collinear; Force is varying 0 a) W= ∫ F(x)dx Δ x b) Force is a function of x c) F=kΔx 0 d) W=k xdx ∫ Δ x e) W=kx /2 0 to Δx f) W=½ kΔx 2 5) 2D:Force and direction are coplanar; Force is varying xf yf