| This might sound trivial, but I've always been curious as to why exactly when you put your finger on the top of a straw in a drink and lift it up, the liquid stays in it. We're studying pressure and fluids right now in my physics class, and I have a general idea that it has to do with the pressure of the outside air pushing up on the liquid in the straw. What I don't understand is exactly how to describe the whole thing. Shouldn't the pressure of the air in between the liquid and your finger be the same as it was before you put your finger on the straw? Does that pressure actually change at all just from enclosing it? And if it doesn't change, then wouldn't the same forces be acting on the liquid that were acting on it before you put your finger on it? thanks in advance |
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| When you put your finger on the straw, the juice does move down a bit. As it does so, your finger prevents air from entering the top of the straw, which produces a vacuum. The force caused by the air pressure at the bottom of the straw trying to get into that vacuum is exactly balanced with the force of gravity, preventing the juice from moving. The reason it doesn't simply bubble up the straw is because of the surface tension on the boundary between air and liquid. This same force is what allows you to drink from a straw. You suck the air out and air pressure at the top of the juice glass forces the juice at the bottom into the straw to replace it. Nature abhors a vacuum. Its a bit confusing but I hope I was able to clear it up a bit |
| Google it. |
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| Google is your friend. https://www.physicsforums.com/threads/why-does-the-liquid-stay-in-the-straw.434003/ |
 I respect your opinion as long as you respect mine. |
Joey_DarKSidE said: When you put your finger on the straw, the juice does move down a bit. As it does so, your finger prevents air from entering the top of the straw, which produces a vacuum. The force caused by the air pressure at the bottom of the straw trying to get into that vacuum is exactly balanced with the force of gravity, preventing the juice from moving. The reason it doesn't simply bubble up the straw is because of the surface tension on the boundary between air and liquid. This same force is what allows you to drink from a straw. You suck the air out and air pressure at the top of the juice glass forces the juice at the bottom into the straw to replace it. Nature abhors a vacuum. Its a bit confusing but I hope I was able to clear it up a bit Wow nice answer cleared it up for sure |
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| Cohesion. It's a property of water and most water based liquids. It's cool when you see water sticking to the undersides of enclosures where the rain doesn't hit directly or much at all indirectly. |
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Niddy said: Google it. daky-kun said: Google is your friend. https://www.physicsforums.com/threads/why-does-the-liquid-stay-in-the-straw.434003/ Just fuck off it's casual discussion every thread here is just a disguised blog of a recent event that had happened to somebody that had triggered them to ask a question. you failures couldn't even answer the question in the first place, I'm sure you would have used the opportunity to feed your own ego. |
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| ^ he mad |
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| Weird coincidence that the biggest toxic piles of shit in the thread are weaboo loli-pedophile avatar fags that probably got no where to go in life. Why don't you google that degree LMAO. IT WOULD TAKE ANYBODY THAT ACTUALLY PASSED HIGH SCHOOL 15 SECONDS TO THINK OF THE ANSWER THATS LONGER THAN IT TOOK FOR YOU TO COME UP WITH THAT "GOOGLE IT" RESPONSE Yep, Mal is dead. |
clockmasterx said: Calm down nig.Niddy said: Google it. daky-kun said: Google is your friend. https://www.physicsforums.com/threads/why-does-the-liquid-stay-in-the-straw.434003/ Just fuck off it's casual discussion every thread here is just a disguised blog of a recent event that had happened to somebody that had triggered them to ask a question. you failures couldn't even answer the question in the first place, I'm sure you would have used the opportunity to feed your own ego. |
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| Man everyone is kind of angry. |
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| lotta sensitive folk in this thread.. |
| Ummm, because you're blocking the liquid with your tongue? |
My waifu, do not steal.  |
Azumaoru said: Ummm, because you're blocking the liquid with your tongue? No, if you put your tongue on the top of the straw, it should flow out the bottom, but it doesn't. Btw OP, I found where you copy and pasted this from LOL https://www.physicsforums.com/threads/why-does-the-liquid-stay-in-the-straw.434003/ |
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| I hate straws some irrational reason. |
| Anyone who doesn't hate anime hasn't watched enough anime. - Anonymous |
JKelbe said: Weird coincidence that the biggest toxic piles of shit in the thread are weaboo loli-pedophile avatar fags that probably got no where to go in life. Why don't you google that degree LMAO. IT WOULD TAKE ANYBODY THAT ACTUALLY PASSED HIGH SCHOOL 15 SECONDS TO THINK OF THE ANSWER THATS LONGER THAN IT TOOK FOR YOU TO COME UP WITH THAT "GOOGLE IT" RESPONSE Yep, Mal is dead. Ok who's shitty alt is this? |
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Happy_Halloween said: Maybe it's yours.JKelbe said: Weird coincidence that the biggest toxic piles of shit in the thread are weaboo loli-pedophile avatar fags that probably got no where to go in life. Why don't you google that degree LMAO. IT WOULD TAKE ANYBODY THAT ACTUALLY PASSED HIGH SCHOOL 15 SECONDS TO THINK OF THE ANSWER THATS LONGER THAN IT TOOK FOR YOU TO COME UP WITH THAT "GOOGLE IT" RESPONSE Yep, Mal is dead. Ok who's shitty alt is this? |
My waifu, do not steal. |
Azumaoru said: Happy_Halloween said: Maybe it's yours.Ok who's shitty alt is this? the plot thickens |
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| Cohesion like someone above said. Surface tension is still my favorite among the weird shit that water can do though lol. |
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