Why does water go gluglugglug when we pour it too fast? Will it take a shorter time to empty the container if we pour a bit slower?
In: Physics
In order for water to get out of the container, air has to get in to replace the lost volume. Otherwise you end up with a vacuum in the container and the water gets sucked *in*, not out.
If you pour normally, the water comes out the lower part of the opening and air goes in (at the same rate). But if you pour too fast, the water fills too much of the opening and the air starts to meaningfully speed up to get through the opening. This causes the pressure in the opening to drop, which pulls the water up to fill the opening. Once the water fully fills the opening it’s all water out, no air in, so you start to build a vacuum in the container. Once this gets strong enough to reverse the flow, the water stops and you get a “glug” as a slug of air gets pulled into the container. Now the water charges forward, plugging the opening again, and the cycle repeats…glug, glug glug.
You almost always get a faster total flow by going just up to, but not over, the “glug point”.
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