Why Liquids Form Drops and Float

Surface tension and surface energy explain why liquids behave the way they do at their surface. A paint brush moves freely in water, but its bristles stick together after it is taken out. That change is caused by surface tension.

Inside a liquid, bulk molecules feel attractive forces from nearby ...

Liquid surfaces behave like a stretched membrane, meaning they tend toward surface area minimization. This property is called surface tension.

Molecules inside the liquid experience attractive forces equally on all sides from the surrounding molecules. But, surface molecules experience asymmetric forces.

The net inward force on sur...