Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: raineywoods on 26/11/2014 18:32:05
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I notice when I remove my tea bag after steeping it in a cup of water, it always spins in a clockwise fashion. Does anyone know the physics behind this reaction?
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That's the way the string is twisted?
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Check with an unused teabag - if they still spin clockwise then that's just a product of the manufacturing process. If not, then I expect it comes from a habit you have in the way you pour the water from the kettle into the mug.
Having just made a cuppa myself, I suspect that it is an artifact of habit. Personally I am right-handed, and the most accurate way to make sure I don't spill the water is to pour it into the opposite side from me, which results in an anticlockwise rotation of the water as I fill the mug, so naturally the bag unwinds clockwise.
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Check with an unused teabag
They rarely rotate significantly until wet.
which results in an anticlockwise rotation of the water as I fill the mug, so naturally the bag unwinds clockwise.
Not if the teabag is resting against the side or bottom of the mug.
I'm still with Bored Chemist on this.
BTW, as someone who rarely uses teabags with strings, my mental image on reading the OP was of a teabag being spooned out of a mug and gyrating on the spoon. I suspect that would have lead to a lively thread. [;D]
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They rarely rotate significantly until wet.
Then soak a teabag in hot water (while preventing its rotation) to prove that it's not being wet that causes the rotation somehow?
Not if the teabag is resting against the side or bottom of the mug.
I find that generally the water has sufficient angular momentum to lift the teabag and cause it to rotate with the water, even in such a case as you describe.
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<<Why does my tea bag always rotate clockwise...>>
Answer: because it's a "tea time" bag [:)]
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It also occurs with the drainage of water in a toilet bowl. It either depends on the manufacturer or which side of the equator you are on.
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It also occurs with the drainage of water in a toilet bowl. It either depends on the manufacturer or which side of the equator you are on.
That's an urban myth ...
... no consistent difference in rotation direction between toilet drainage in the Northern and Southern Hemispheres can be observed...
http://en.wikipedia.org/wiki/Coriolis_effect#Draining_in_bathtubs_and_toilets
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It also occurs with the drainage of water in a toilet bowl. It either depends on the manufacturer or which side of the equator you are on.
As RD explained, that's a common misconception. It's based on the assumption that it's caused by Coriolis forces acting on the water. The fact is that it's due to things such as the direction in which water leaves your toilet and the shape of the bowl and the angle at which the liquid initially enters that bowl. If there was a container of water which had a hole at the bottom which was simply "unplugged" with no rotation acting during the unplugging then there's no way to determine which way it will rotate, if it rotates at all. It might rotate according to the Coriolis effect but the effect is miniscule to have a large effect on the direction of direction of the water.
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It also occurs with the drainage of water in a toilet bowl. It either depends on the manufacturer or which side of the equator you are on.
That's an urban myth ...
... no consistent difference in rotation direction between toilet drainage in the Northern and Southern Hemispheres can be observed...
http://en.wikipedia.org/wiki/Coriolis_effect#Draining_in_bathtubs_and_toilets
It also occurs with the drainage of water in a toilet bowl. It either depends on the manufacturer or which side of the equator you are on.
As RD explained, that's a common misconception. It's based on the assumption that it's caused by Coriolis forces acting on the water. The fact is that it's due to things such as the direction in which water leaves your toilet and the shape of the bowl and the angle at which the liquid initially enters that bowl. If there was a container of water which had a hole at the bottom which was simply "unplugged" with no rotation acting during the unplugging then there's no way to determine which way it will rotate, if it rotates at all. It might rotate according to the Coriolis effect but the effect is miniscule to have a large effect on the direction of direction of the water.
Thanks for the clearification.
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Thanks for the clearification.
My pleasure! :)
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Update to the OP: Twinings Spicy Chai tea bags rotate anti-clockwise! [;D]
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Update to the OP: Twinings Spicy Chai tea bags rotate anti-clockwise! [;D]
That's a great find! Only spend about 4 months.
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After some Googling, i came upon this old post.
My query is the same,
BUT!
When my teabag is on the string inside the mug suspended from the bottom and edges it spins anti-Clockwise until it comes to a stop, when the bag is removed from the cup, it spins clockwise until it comes to a stop, once inserted back into the water, spins anti-clockwise, repeats over and over for both actions.
why?
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Well, I don't think it's the Coriolis effect, neither Brownian motion., How about the way the strings strands are twisted together? Combined with the elasticity and tension of a drier relative wetter string?
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Hi Bunty Chops, welcome to the emporium of wisdom and tea bags.
I applaud you investigative enthusiasm, but I have to ask if you like your tea cold?
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Couldn't we name this wet string theory?
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Well, I don't think it's the Coriolis effect, neither Brownian motion., How about the way the strings strands are twisted together? Combined with the elasticity and tension of a drier relative wetter string?
String twist is likely the correct answer. When you are holding the bag above the tea. The string is under the tension of the weight of the tea bag. when you lower it into the tea the weight of the bag is partially supported by the tea, this relaxes the tension on the string, allowing the twist to "relax", which rotates the bag. Lifting the bag out again puts tension back on the string, tightening it up the twist, and rotating the bag back. A wet tea bag pulled out of the tea should rotate "back" more than a dry tea bag initially rotated when put in as the wet tea bag will be heavier and put more tension on the string.
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Check with an unused teabag - on the off chance that despite everything they turn clockwise, that is only a result of the assembling procedure. In the event that not, I expect it originates from a propensity you have in the manner in which you pour the water from the pot into the mug.
Having quite recently made a cuppa myself, I speculate that it is a curio of propensity. By and by I am correct given, and the most precise approach to ensure I don't spill the water is to empty it into the contrary side from me, which results in an anticlockwise revolution of the water as I fill the mug, so normally the pack loosens up clockwise.
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Check with an unused teabag - on the off chance that despite everything they turn clockwise, that is only a result of the assembling procedure. In the event that not, I expect it originates from a propensity you have in the manner in which you pour the water from the pot into the mug.
Having quite recently made a cuppa myself, I speculate that it is a curio of propensity. By and by I am correct given, and the most precise approach to ensure I don't spill the water is to empty it into the contrary side from me, which results in an anticlockwise revolution of the water as I fill the mug, so normally the pack loosens up clockwise.
That reminds me Kamel, usually as you pour the water on to the teabag, the string and tab dissappear into the cup in the manner you are suggesting !
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I notice when I remove my tea bag after steeping it in a cup of water, it always spins in a clockwise fashion. Does anyone know the physics behind this reaction?
most likely it has to do with the twist of the tea bag string! lol