Why do small objects grip to wet surfaces best, but large objects grip to wet surfaces worse than a dry surface?

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My question probably doesn’t even make sense so here is an example. If you pour water over a massive boulder and throw sand at it, the sand will stick to the rock better than it would without the water. For larger objects like your hand, it would make it much harder to climb that rock than without the water poured on it. Why is it the opposite?

In: Physics

3 Answers

Anonymous 0 Comments

If a surface is wet, the water reduces friction. Just like grease, water is not solid and basically allows you to slip off a surface, just like a boat can go over water, but not land.

Small objects stick to water, because of the surface tension. The object itself is not heavy enough to break the friction between water molecules, so the water and sand stay in place.

You could picture it as a steep incline with a very thin rope. If you are light enough, the rope will help you climb, but if you are too heavy the rope will break and you fall down.

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