- Plastic mesh bag used for produce at the grocery store
- Wide mouth bottle
- Rubber band
- Index card
- Pitcher of water
- Bucket to catch the falling water
How does it work?
If you dip a piece of the screen (the mesh bag) into a glass of water, you notice that the water fills the screen holes. A force called cohesion, which is the attraction of molecules that are the same to each other, causes this effect. The surface tension “membrane” is always trying to contract, which explains why falling droplets of water are spherical or ball shaped. The water stays in the bottle even though the card is removed because the molecules of water are joined together to form a thin membrane between each opening in the screen. Tipping the bottle or touching the screen will break the surface tension and surprise everyone with a gush of water!