Re: When pouring a liquid, why do tiny drops sometimes skim the surface?

Hi Jill,

I'm guessing a little bit on this one. The molecular attraction which causes surface tension is the same in a water droplet as in the liquid which is already in a container, such as a teacup. However, surface tension causes a droplet to assume a spherical shape, because that is the minimum energy configuration. That, for example, is why a thin layer of water on a surface will break up into droplets rather than form a continuous film (unless the water has a strong adhesion to the surface). You will therefore have to put energy into a droplet in order to break it apart and get it to join with the liquid in the teacup. The kinetic energy given to the water as you pour it is usually enough to do this, but some droplets may form, and retain their identity for a time.