A bar magnet is released from rest along the axis of a very long vertical copper tube. After some time the magnet will.

According to Lenz's law, there is an opposition for motion of magnet when flux associated with tube changes with time. Due to change in flux, eddy currents are developed in tube which offers retarding force on magnet. After some time, speed of magnet increases due to which eddy currents increases so more opposition for magnet.
Finally at some instant retarding force balance the weight of magnet so it moves with constant speed.