Magnetic Force on a Sliding Bar

A conducting bar (green) moves over two frictionless parallel rails (yellow) with a resistance . It creates a current due to the presence of a uniform magnetic field that is directed into the figure (marked with ×'s). The bar has mass , length , and initial velocity (blue) toward the right. After release at , position and velocity as a function of time are shown. Note that the induced current is counterclockwise and the magnetic force (orange) points in the direction opposite to the motion.