A miniature model train carrying a 1.2 m long straight metal rod is moved along a circular track within a uniform magnetic field. The field has a strength of 2.0 × 10 ^-4 T and is oriented perpendicularly to the track. If the scientists want to measure a motional emf of 2.0 V induced in the rod, how fast should the model train travel? Assume that the motion of the rod is perpendicular to the magnetic field.