Chapter 14, Problem 86CP

A rectangular copper ring, of mass 100 g and resistance 0.2 1, is in a region of uniform magnetic field that is perpendicular to the area enclosed by the ring and horizontal to Earth’s surface. The ring is let go from rest when it is at the edge of the nonzero magnetic field region (see below). (a) Find its speed when the ring just exits the region of uniform magnetic field. (b) If it was let go at t = 0, what is the time when it exits the region of magnetic field for the following values: $a=25\text{cm,}\text{b = 50 cm B = 3T }$ , and $g=9.8m/s^2$ ? Assume the magnetic field of the induced current is negligible compared to 3T.