Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 11/03/2016 16:50:01
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Lynne Fouquette asked the Naked Scientists:
Every day I transfer chilled water from a tapered neck, glass bottle to another vessel (to carbonate it with a CO2 cartridge.) Being impatient, I want to pour it as quickly as possible. There seem to be two ways to pour: tipping the bottle slightly, allowing a smooth stream of water going out as the air replaces it in the bottle, or the "glug-glug" method where the bottle is at a more acute angle and water pours, then stops momentarily as the air rushes in to replace it in the bottle. My question is which is faster, if there is any difference at all. My common sense tells me that there shouldn't be any difference, but my common sense commonly betrays me when it comes to physics questions.
I love, LOVE your program(s). I listen every day on my commute. Thank you so much for your commitment to disseminating research!
Lynne Fouquette
What do you think?
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Dear Lynne
We did an experiment to test the fastest way to empty a bottle (http://www.thenakedscientists.com/HTML/experiments/exp/the-fastest-way-to-empty-a-bottle/). It's all to do with how to replace the water with air; this needs to happen otherwise the void left by the departing water is a vacuum which will oppose the exit of more water.
The solution (excuse the pun) we offer is to swirl the bottle. The resulting vortex (whirlpool) has a central column of air that can enter smoothly and continuously, allowing a rapid exit for the water.
Try that and let us know how you get on!