Julie’s town uses single-stream recycling, so julie puts all of her household recyclables in a single container to be picked up. the recycling plant must sort out the different materials, including paper, cardboard, different types of plastic, glass bottles and jars, aluminum drink cans, and steel food cans.

how would an electromagnet be used in this type of recycling plant?

to remove plastic bottles from glass bottles
to divide food cans from soft-drink cans
to separate paper from cardboard
to gather colored glass from colorless glass

to divide food cans from soft-drink cans      

Explanation:

An electromagnet is based on the principle that current through a coil produces magnetic field. Magnetic objects such as Iron, nickel, cobalt or objects made from their combination are attracted by the magnet. This property is used to separate materials in recycling plant.

Steel (alloy of iron)  would be attracted by the magnet where as aluminium would not be. Thus, steel food cans can be separated from the aluminium soft-drink cans using an electromagnet.

its temperature is increasing. this causes molecular vibrations to increase.