That's an excellent question that touches on urban infrastructure we see every day but rarely think about! The weight of an empty public trash can isn't a single number, as it varies significantly based on material and size.
The most common type you'll encounter on city sidewalks is a plastic barrel-style bin. An average, empty 40-50 gallon plastic trash can typically weighs between 15 and 30 pounds (7 to 14 kg). They are designed to be lightweight for easy handling by sanitation workers.
For more heavy-duty or decorative purposes, cities use metal bins, usually made of galvanized steel. An empty metal trash can of a similar size can weigh a substantial 50 to 100 pounds (23 to 45 kg) or more, making them much more difficult to tip over or vandalize.
Smaller pedestrian bins, often attached to lampposts, are naturally lighter, usually in the 5 to 15-pound (2 to 7 kg) range. So, while there's no universal weight, you can generally expect an empty public bin to be heavier than it looks, especially if it's metal!