In the figure below, a rectangular conducting wire of width L, resistance R, and mass m, is suspended in an area with a uniform magnetic field B pointing outwards, which is just above the dotted line.  Below the dotted line there is no magnetic field.  If this wire is dropped and during the fall it accelerates until it reaches a final velocity (terminal speed) vt. If the air friction is neglected, determine 

(a) the equation vt

(b) in which direction the induced current flows in the wire.