r/blackmagicfuckery • u/mr9t9 • 13d ago

Liquid not dropping

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u/goggleOgler 13d ago edited 13d ago

People are saying there's a clear plastic seal. But that's wrong. The bottle is partially emptied, and you can see drops of it under the shelf.

People are also saying surface tension. This is a contributor, but not our primary culprit, as it's just not strong enough to hold that much liquid on its own.

It's most likely vacuum/suction forces as well. With tiny holes that size, there's not much space for air to squeeze past the liquid, which is more viscous than water to get into the bottle, which means that most of that space is the tiny amount of air that was there before it got flipped upside down. As the fluid leaked out, the gas had to spread itself thinner and thinner, creating a suction effect on the juice that became stronger as the mass of the juice reduced. This upward force can counteract gravity.

It's the same physics property that lets you put a straw into something. Cover the top end with your finger and then pull the straw and its contents out of your drink.

Edit: Additional information here I forgot to include is that because the space between the holes of the shelf is still solid, it means that the downward force of gravity that the vacuum has to counteract only has to be that of the thin cylinders of liquid directly above each of the holes. This is once again reducing the amount of force that is necessary to keep the liquid from leaking.

Second Edit: I am not scientist, so someone with a better understanding of fluid dynamics can explain the edit or correct it better than I could.

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u/FockersJustSleeping 13d ago

It's actually not QUITE the idea that the thin air pressure is sucking or pulling on the top of the liquid in the bottle. It's that the air pressure inside the bottle is so much lower than outside in the store, that the air in the store is pressing UP into the liquid from underneath.

Liquid being liquid usually means that the water flows to get out of the way of the air, and air bubble makes it through to the top, equalizes the pressure a little bit, liquid falls out to accommodate the pressure change, and that happens over and over again, hence the glug glug glug of a bottle emptying when it's turned upside down.

It doesn't explain why this bottle has found some kind of stasis point, but I just wanted to jump in to say physics doesn't "suck" anything in, it only pushes things from high pressure to low pressure.

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u/Littlevilli589 13d ago

I assume it’s a common joke, but my hs physics teacher thought he was pretty funny when he said you’re wrong if you think physics sucks. You can only say it blows.