Here's why:
* Cohesive forces: The molecules within a liquid are attracted to each other (cohesion). At the surface, these molecules experience a net inward force because they are only surrounded by other liquid molecules on one side.
* Minimizing surface area: This inward force causes the liquid to minimize its surface area, which is why drops form a spherical shape (the shape with the smallest surface area for a given volume).
* Surface tension: This tendency of a liquid to minimize its surface area due to the inward cohesive forces is what we call surface tension.
Think of it like a stretched rubber sheet – it wants to shrink back to its smallest size, just as a liquid droplet wants to minimize its surface area.
