A circuit consists of two very low-resistance rails separated by 0.300 m, with a 50.0 ohm resistor connected across them at one end and a conducting, moveable bar at the other end. The circuit is in a uniform 0.100 T magnetic field that is parallel to the area vector of the circuit. The bar is moving at a constant velocity such that the resistor dissipates 1.50 W of power. What is the speed of the bar?