A rod of mass m and radius R rests on two parallel rails (Fig. P29.15) that are

Question:

A rod of mass m and radius R rests on two parallel rails (Fig. P29.15) that are a distance d apart and have a length L, the rod carries a current I (in the direction shown) and rolls along the rails without slipping. A uniform magnetic field B is directed perpendicular to the rod and the rails. If it starts from rest, what is the speed of the rod as it leaves the rails?