eli5 why can a straw carry water without the bottom dripping but not a pool?

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Essentially my question is this: if I get a straw and put it in water, I cover my thumb on the top and pull out, water doesn’t want to leave. Idk why or how but regardless.

How come this same thing doesn’t apply for a swimming pool? Like a body of water is suspended because it has a lid or roof?

In: Physics

10 Answers

Anonymous 0 Comments

you are thinking about this the wrong way, the water is not suspended because of a lid or a roof or in the example of the straw the finger.

all the finger does is prevent air from getting in from the top so now in order for the water to drop down air needs to come in from the bottom.

Because the straw is narrow and theres only very little water in it the surface tension of the water is strong enough to hold the water up and prevent air from getting in.

if you increase the surface area and mass of the water by using a very large straw the surface tension wont be strong enough to hold all the weight and everything will drop down.

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