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Mercury exhibits more cohesion than adhesion with glass Rain water flux from a canopy. Among the forces that govern drop formation: cohesion, surface tension, Van der Waals force, Plateau–Rayleigh instability. Water, for example, is strongly cohesive as each molecule may make four hydrogen bonds to other water molecules in a tetrahedral ...
Cohesion is the component of shear strength of a rock or soil that is independent of interparticle friction. In soils, true cohesion is caused by following: Electrostatic forces in stiff overconsolidated clays (which may be lost through weathering) Cementing by Fe 2 O 3, Ca CO 3, Na Cl, etc. There can also be apparent cohesion. This is caused by:
For example, the mass of a sample is an extensive quantity; it depends on the amount of substance. The related intensive quantity is the density which is independent of the amount. The density of water is approximately 1g/mL whether you consider a drop of water or a swimming pool, but the mass is different in the two cases.
This occurs between water and glass. Water-based fluids like sap, honey, and milk also have a concave meniscus in glass or other wettable containers. Conversely, a convex meniscus occurs when the adhesion energy is less than half the cohesion energy. Convex menisci occur, for example, between mercury and glass in barometers [1] and thermometers.
Flotation of objects denser than water occurs when the object is nonwettable and its weight is small enough to be borne by the forces arising from surface tension. [5] For example, water striders use surface tension to walk on the surface of a pond in the following way. The nonwettability of the water strider's leg means there is no attraction ...
Cohesion causes water to form drops, surface tension causes them to be nearly spherical, and adhesion keeps the drops in place. Water droplets are flatter on a Hibiscus flower which shows better adhesion. In surface science, the term adhesion almost always refers to dispersive adhesion.
The theory is intended to explain how water can reach the uppermost parts of the tallest trees, where the applicability of the cohesion-tension theory is debatable. [ 7 ] The theory assumes that in the uppermost parts of the tallest trees, the vessels of the xylem are coated with thin films of sap.
The unusual density curve and lower density of ice than of water is essential for much of the life on earth—if water were most dense at the freezing point, then in winter the cooling at the surface would lead to convective mixing. Once 0 °C are reached, the water body would freeze from the bottom up, and all life in it would be killed. [36]