MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Surface tension. Metal needle floating on the surface of a glass of water due to surface tension. Surface tension is caused because the attraction (cohesion) between the water molecules makes the surface behave like an elastic skin. The surface layer is therefore able to support the needle, even though metal is denser than water. If the needle were pushed through the surface layer, it would sink to the bottom of the glass.
Model release not required. Property release not required.