Long enough vertical rails distance L from each other made of an ideal conductor are connected by a resistor R. A bar of mass M, also made of an ideal conductor, can slide along the rails without friction and without loosing electrical contact with the rails. A uniform magnetic field B is horizontal and perpendicular to the plane of the rails. At some point the bar was released with zero initial velocity.Find its velocity after long time. Find the bar's velocity as a function of time (for all times).