A metal crossbar of mass m slides without friction on two long parallel conducting rails a distance b apart. A resistor R is connected across the rails at one end; compared with R, the resistance of the bar and rails is negligible. There is a uniform field B perpendicular to the plane of the figure. At time t = 0 the crossbar is given a velocity of magnitude v0 toward the right. What happens next? Does the rod ever stop moving? If so when? How far does it go? What about conservation of energy?

A metal crossbar of mass m slides without friction on two long parallel conducting rails a distance b apart. A resistor R is connected across the rails at one end; compared with R, the resistance of the bar and rails is negligible. There is a uniform field B perpendicular to the plane of the figure. At time t = 0 the crossbar is given a velocity of magnitude v0 toward the right. What happens next? Does the rod ever stop moving? If so when? How far does it go? What about conservation of energy?