Usually, only things that are less dense than water will float in water. However, when liquid meets gas, it has surface tension. The water molecules touching the air are packed together more tightly, producing a sheet of surface tension on top of the water. This allows the surface of the water to sometimes support things that do not normally float.
- 2 Paperclips
- Piece of Tissue Paper
- Bowl of Water
1. Try to float one paperclip on the surface of the water. Did it sink or float?
2. Cut or tear a piece of tissue paper just a little bigger than the dry paperclip.
3. Gently place the tissue paper on the surface of the water.
4. Carefully, place the dry paperclip on top of the tissue paper.
5. Slowly, push the tissue paper down into the water using your finger. Make sure not to touch the paperclip while doing this!
6. This may take a few tries, but the surface tension should be able to support the paperclip once the tissue paper has been moved.
Explore more! Some insects, such as water striders, use surface tension to walk on water! They distribute their weight between their limbs to move across the water without breaking the surface tension and sinking. These animals are called pleuston, which means surface-living.