According to the United States Geological Survey, capillary action occurs due to the forces of surface tension, cohesion and adhesion. Capillary action is the tendency for water to move with the spaces of a porous material. For example, when a paper towel is placed in a glass of water, the water travels up the paper towel until the force of gravity overpowers the capillary forces.Continue Reading
Cohesion is the tendency for water molecules to stick together, whereas adhesion is the tendency for water molecules to stick to other substances. When combined with the tendency of water to resist external forces, which is also known as surface tension, water and other liquids climb up the sides of a thin glass vessel, called a capillary tube. HowStuffWorks explains that the diameter of the capillary tube and the ambient temperature affect the distance that the liquid rises.
There are many examples of capillary action in the natural world. According to HowStuffWorks, compact soil contains small spaces between the grains of dirt. Water rises through the soil via capillary action and evaporates upon reaching the surface. Additionally, as explained by USGS, plant roots rely on capillary action to draw water from the ground and transport it to the plant’s trunk, branches, twigs and leaves.Learn more about Motion & Mechanics
One example of adhesion is water climbing up a paper towel that has been dipped into a glass of water, and one example of cohesion is rain falling as drops from the sky. During adhesion, water is attracted to other substances, causing the positive and negative molecules of the water to be attracted to the paper. During cohesion, water is attracted to itself and turns molecules into drops.Full Answer >
In chemistry, adhesion refers to the tendency of unlike molecules to bond with one another, while cohesion refers to the attractive force between molecules of the same type. Surface tension, which is an essential property of water, illustrates the relationship between adhesion and cohesion.Full Answer >
The main source of attraction between two metals, or adhesion, is what causes friction, and any increase of friction requires an increase in adhesion. Friction itself is the force of resistance against two objects as one object slides or rolls over another. This force increases the amount of energy required to move an object a set distance.Full Answer >
The primary causes of friction are surface roughness, the plowing effect and molecular adhesion. Surface roughness is when serious abrasion occurs due to the roughness of the materials in contact. The plowing effect involves deformations of the objects that cause resistance to movement when the materials are relatively soft.Full Answer >