PHY 2054 Midterm: 2054_Spring13_Exam3_Solutions
Document Summary
Exam 3 solutions: an electron and a proton, located far apart and initially at rest, accelerate toward each other in a location undisturbed by any other fields or particles. Just before they collide, the ratio of their kinetic energies, Recall that the kinetic energy can be written as. Solution: because of equal and opposite electrical forces, we have conservation of momentum, meve. Thus the ratio of kinetic energies is, using equality of momentum, 2: four particles of charge q are fixed at the corners of a square with sides of length l, as shown in the figure. One particle is moved from its original posi- tion to the center of the square by an external force. The work performed by the external force is: Solution: the initial potential energy of particle 4 (caused by particles 1, 2 and 3) is force is. Wext = !we = "u = 5 / 2 !
