Eli5 why does not gravity pull the water down from a sponge or any other absorbant material?
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Because the adhesion force between the water and that absorbent material is stronger than the gravitational pull on the water from the Earth. Water has physical properties that can make it move against gravity in certain circumstances. This is how trees are able to extract water from the roots to feed leaves despite the fact that the cells that transport the water are dead and thus there isn’t any active pumping of the water.
It does. But the electrostatic attraction between the sponge and the water is stronger. “But what if it’s weaker?” well then it’s a really bad sponge, and the water will flow out of it and to the ground.
It actually does.
If you soak a sponge and sit in on your counter for a day, you’ll find that the water has moved to the bottom while the top is drier.
It just takes time because the water has to move through material. So it’s not quick, but it happens.
For essentially the same reason it doesn’t pull your phone out of your hand toward the floor. Your grip is stronger than the gravitational force.
Gravity is actuallly incredibly weak. A tiny fridge magnet is enough to resist the pull of the whole planet. So are your legs, every time you stand up, come to that. And there are strong attractive forces between the water and the sponge – gravity doesn’t stand a chance.
Gravity wins big time out over huge distances, though, because it drops off in strength more slowly than other forces. When the others have given up, gravity just keeps on going.
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