These capillary phenomena are macroscopic manifestations of molecular interactions, and can be explained in terms of surface tension. For students, the concept of surface tension is quite challenging since the microscopic intuition is often in conflict with the common macroscopic interpretations. read more
The force opposite the mass of the object on the surface, is still parallel to the liquid surface, but at this point, parallel is pointing at an angle up. These vector forces are all around the object and they cancel the downward force. read more
However, there is a tension in the surface. This can be seen because a particle at the surface only experiences half the interaction energy it is supposed to. Thus there is a certain energy you have to pay to create a unit of surface area. The surface tension is exactly the constant of proportionality between energy and surface area. read more
Sketch showing the surface tension as a force per unit length exerted by one subsystem on the other. The system on which the forces act is the dotted region. The force is parallel to the interface and perpendicular to the dividing line. read more