For 10 points, name this contractive tendency that allows liquids to resist an external force, and is the reason why some insects can walk on water.
The Gibbs-Marangoni effect is caused by a gradient in this phenomenon, while another effect of this is explained by Plateau-Rayleigh instability. This phenomenon can be measured by the Wilhelmy plate, Du Noūy ring, and pendant drop methods. This quantity is measured in units of energy per unit area, and its strength is reduced by surfactants. This phenomenon, which is represented as γ in the Young-Laplace equation, is the cause of puddling and capillary action. For 10 points, name this contractive tendency that allows liquids to resist an external force, and is the reason why some insects can walk on water.
The Gibbs-Marangoni effect is caused by a gradient in this phenomenon, while another effect of this is explained by Plateau-Rayleigh instability.
ANSWER:{ surface tension}