Damped and forced oscillations, resonance — practice question

A bar magnet with mass $180\,\text{g}$ is hung from the free end of a spring, as shown in Fig. 2.1. The magnet is positioned so that one pole lies close to the middle of a coil of wire. The coil is joined in series with a resistor and a switch, and the switch is open. The magnet is moved vertically and then released so that it oscillates, with one pole staying inside the coil and the other pole remaining outside it. At time $t = 0$, the magnet is oscillating freely as it goes through its equilibrium position. At time $t = 3.0\,\text{s}$, the switch in the circuit is closed. The graph in Fig. 2.2 shows how the vertical displacement $y$ of the magnet varies with time $t$.