What is referred to as the force within a liquid's surface?

Surface tension refers to the cohesive forces that cause the molecules on the surface of a liquid to be attracted to each other more strongly than they are to the air above. This results in a thin "film" on the surface, giving the liquid its shape and causing it to behave as if its surface were covered with an elastic membrane. This phenomenon is crucial in various applications, from understanding how small objects can float on water without sinking to how insects can walk on the surface of a pond.

The other terms do not describe the force within a liquid's surface. Liquid pressure relates to the force exerted by the liquid in all directions at a specific depth, while fluid dynamics studies the motion of fluids and the forces acting on them. Viscosity is a measure of a fluid's resistance to flow, indicating how “thick” or “sticky” a liquid is. Each of these concepts is important in the study of fluid behavior, but surface tension specifically captures the unique properties of the liquid's surface layer.