One tube is made of copper, the other from plastic. From which tube will the magnet emerge first? Why?
plastic because there is no magnetic field to provide resistance.
The magnet from plastic tube would emerge first. This is so because electric emf will be produced in both due to changing magnetic field. But eddy currents will be stronger in copper tube because of free electrons. These currents will apply a retarding force on the moving magnet. In other words copper tube will itself become a stronger electromagnet with a polarity that opposes the motion of the magnet. this effect will be negligible in plastic tube because it has almost no free electrons.
