What do you think would happen if you stuck some pencils through a plastic bag filled with water? It would start to leak, right? At least, that is what I thought before I did this experiment. This is a mind-blowing experiment that is SUPER easy to conduct.
What you need:
- A plastic bag
- Water
- Sharpened pencils
- A tray
Steps:
- Pour the water into the plastic bag and seal the bag
- Poke the pencils straight through the bag
- Make sure to keep a tray underneath the plastic bag in case it starts leaking water
- Watch in amazement as the pencils slide through the bag without leaking any water!
So how does this work?
Most plastic bags are made out of a polymer called low-density polyethylene. This polymer is very widely used because it is low in cost, lightweight, durable, a barrier to moisture, and very flexible. The tip of the sharpened pencil can easily slip between the molecules of the polymer, but the polymer’s flexible property helps to form a temporary seal against the edge of the pencil. When the pencil is removed, the hole in the plastic bag remains because the polyethylene molecules were pushed aside permanently, and the water leaks out.