Question

Small insects can walk across the surface of calm water. Their feet push the surface of the water down slightly, somewhat like a person walking across a trampoline, but they do not break the surface. What is the best explanation for why this happens

Answer 1

Answer:

Explanation:

Molecules within a liquid are pulled in all directions by intermolecular forces; there is no tendency for them to be pulled in any one way. However, molecules at the surface are pulled downward and sideways by other molecules, but not upward away from the surface. These intermolecular attractions thus tend to pull the molecules into the liquid and cause the surface to tighten like an elastic film.

A measure of the elastic force in the surface of a liquid is surface tension. The surface tension is the amount of energy required to stretch or increase the surface of a liquid by a unit area.  Surface tension enables small insects, like the water strider, to “walk” on water.