Navigating in the Big Dipper. All of the stars of the Big Dipper (part of the constellation Ursa Major) may appear to be the same distance from the earth, but in fact they are very far from each other. Figure P1.91 shows the distances from the earth to each of these stars. The distances are given in light-years (ly), the distance that light travels in one year. One light-year equals 9.461 * 1015 m. (a) Alkaid and Merak are 25.6o apart in the earths sky. In a diagram, show the relative positions of Alkaid, Merak, and our sun. Find the distance in light-years from Alkaid to Merak. (b) To an inhabitant of a planet orbiting Merak, how many degrees apart in the sky would Alkaid and our sun be?
PHYS 221 General Physics II 01/23/17 Dielectrics, Capacitors Lecture 4 Spring 2016 Electric field, electric potential Potential DiffereDevice is used for*independent of path Last Lecture electrocardiograms*independent of test charge • Electric force is conservative To find ▯V, find work done on a positive charge q by • Electric potential enerthe electric field as it moves from i to f. • Potential i PE elect −W elect −qEΔx The work done on the particle by electrostatic