Capillary pressure

Capillary pressure is like when you suck liquid from a straw. Your mouth creates a vacuum that pulls the liquid up the straw. The smaller the straw, the harder it is to suck up the liquid because the liquid gets stuck on the sides of the straw.

Capillary pressure is like the liquid getting stuck on the sides of the straw. It happens when there are very small spaces, called capillaries, that liquids have to flow through. These spaces can be found in things like soil, rocks, or plants.

If the spaces between the capillaries are bigger than the liquid molecules, the liquid will flow freely. But if the spaces are smaller, the liquid will be "stuck" and it will need extra force to move through. This extra force is called capillary pressure.

Think of it this way: imagine a big group of people trying to squeeze through a small doorway. They can't all fit through at once, so they have to push and squish to get through. That pushing and squishing is like capillary pressure - the liquid has to push and squish to get through the small spaces between the capillaries.