:what causes this thing where you tip a cup/glass full of liquid and the liquid instead of falling down as soon as it reaches the edge, runs along the side and falls down once it reaches the bottom of the glass/cup?
In: Physics
This happens when the walls of the cup or glass are thick, or when the angle of the pour is shallow. A cup or glass with thin walls (and no “lip”) will allow the liquid to fall quickly down, even when the angle is shallow; a thick-walled or lipped cup will require a steeper angle for the liquid to fall freely.
This is called adhesion. Water is very very sticky and it likes to be attracted to things. It is far more attracted to the side of the glass than the air. Gravity has some effect, but not enough until theirs is more liquors with more mass.
Water also has a property called cohesion, where it sticks to itself. This is why there is a water droplet in the first place. The molecules of water stick to each other, and therefore they go down the side of the glass to stay with the molecules that are attracted to it.
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