Description: both magnitude and direction are available. Generally speaking, it is called vector in physics and vector in mathematics. In the computer, the vector diagram can be infinitely enlarged and never deformed.
Liquid has cohesion and adsorption, both of which are manifestations of molecular gravity. Cohesion enables liquid to resist tensile attraction, while adsorption enables liquid to adhere to other objects. At the boundary between liquid and gas, that is, the interface between the surface of liquid and two immiscible liquids, due to the attraction between molecules, there is a very small pulling force. Imagine that there is a film on the surface that bears the tension of this surface. This tension of liquid is called surface tension.