An electromagnetic rail gun can fire a projectile using a magnetic field and an electric current. Consider two conducting rails that are $0.500 \mathrm{~m}$ apart with a $50.0-\mathrm{g}$ conducting rod connecting the two rails as in the figure with Problem $39 .$ A magnetic field of magnitude $0.750 \mathrm{~T}$ is directed perpendicular to the plane of the rails and rod. A current of $2.00$ A passes through the rod. (a) What direction is the force on the rod? (b) If there is no friction between the rails and the rod, how fast is the rod moving after it has traveled $8.00 \mathrm{~m}$ down the rails?