A physics problem

[ChrisGreaves]

We all know how difficult it is to make a spinning bicycle wheel change direction. I am talking here about holding a front wheel by the axle stub, separate from the bicycle, giving it a good spin, then trying to turn it at right angles; if you try to turn it sideways it goes up (or down) and if you try to turn it up it goes left (or right). No snide comments about The Southern Hemisphere, please!

We know too how hard it is to carry a full mug of tea from the kitchen counter to the living-room without having several dollops of scalding hot tea slosh over the rim of the mug and fall on our slippered feet, if we’re lucky; on the cat otherwise.

So, combining these two observations, oughtn’t the contents of the tea mug be less likely to spill if I give the contents a jolly good stir immediately before setting off from the kitchen?

I mean, instead of sloshing upwards, the tea should continue to go sideways (rotating); perhaps faster, perhaps slower, but rotating nonetheless.

[Rudi]

I am far from a scientist and cannot prove in theory or equation my verdict;

The rotation of the liquid cannot be compared to the rotation force of a spinning wheel (something about centrifugal force springs to mind, if that is relevant or not), HOWEVER, the spinning liquid will be less likely to 'easily' spill or change direction in the cup due to the rotation. The rotation will not stop the spilling, but will contribute to less spilling than if the liquid were just being held by the cup. Also, the spinning will unfortunately not last too long, so by the time you pick up the cup and take a few steps the rotation is lost. How is that for a scientific reply

[HansV]

Why don't you test it? (I'd use cold water instead of scalding hot tea for the experiment)

[ChrisGreaves]

I am far from a scientist and cannot prove in theory or equation my verdict;
The rotation of the liquid cannot be compared to the rotation force of a spinning wheel (something about centrifugal force springs to mind, if that is relevant or not), HOWEVER, the spinning liquid will be less likely to 'easily' spill or change direction in the cup due to the rotation. The rotation will not stop the spilling, but will contribute to less spilling than if the liquid were just being held by the cup. Also, the spinning will unfortunately not last too long, so by the time you pick up the cup and take a few steps the rotation is lost. How is that for a scientific reply

Well!
Congratulations Rudi!!
I am forced to admit that it is one of the very worst I've ever seen posted on this or any other lounge or BBS.

OK, OK, Thank you, thank you ... (smiles and bows).

Back on topic: I AM curious: What made you think that "the spinning liquid will be less likely to 'easily' spill or change direction in the cup due to the rotation"?

I have a vague feeling that by rotating the fluid it ought to be a little more stable, that is, resistant to change, but I can't work out why I think this way.

I agree wrt the wheel vs. coffee debate. A wheel is a rigid material, not a fluid.
FWIW the kinetic energy of a fluid is proportional to the cube of the velocity, that of a solid object to the square, so I know that the mechanics of fluids is different from that of solids.

(Wanders off to the free organ recital ....)

[hlewton]

I tend to look for simpler solutions. Why not put less liquid in the cup? OR use coffee instead of tea. I never have a problem with a full cup of coffee. BTW I don't use cream or sugar, just black that may be the answer. Start simple, try to transport a hot cup of water and proceed from there.

[John Gray]

The way not to spill a cup of tea, coffee, etc, when walking and holding it is to look at the surface of the liquid while walking, and you will automatically make corrections.

This is unlikely to apply, however, if you are drunk, or have some other form of motion impairment.
Or are Chris Greaves...

[BobH]

Don't look at the cuppa. Looking at it almost ensures that your mind will tell your body to compensate for what it perceives as a spill and will over-correct which usually assures a spill. This is a trip learned by wait staff hundreds of years ago.

As for fizzics, I prefer cold Asti Spumante.

[viking33]

Don't look at the cuppa. Looking at it almost ensures that your mind will tell your body to compensate for what it perceives as a spill and will over-correct which usually assures a spill. This is a trip learned by wait staff hundreds of years ago.

As for fizzics, I prefer cold Asti Spumante.

I agree with you on this, Bob. That solution for not looking at the cup or bowl as you carry it, really works! That answer has been around for a longer time than both of us are old!

Also, Asti is a rather pleasant drink that doesn't spill out of the glass, since you tend to drink most of it right where you pour it.

[John Gray]

Watching the liquid works for me...!

[HansV]

Apparently US liquids behave differently than UK liquids...

[Jay Freedman]

I propose an anti-spill cup, with a flywheel built into the base of the cup to provide gyroscopic stabilization. The basic model could use a string wrapped around the flywheel's axle, which you'd pull to spin it up. For additional cost, the deluxe model would have a rechargeable-battery-powered motor.

[Claude]

The far easier solution is not to drink tea

[Leif]

At the risk of stirring things up, wouldn't a Self Stirring Mug solve everyone's problem?

(Available from teAmazon, with Prime delivery )

[HansV]

Chris might give it a whirl...

[Leif]

Chris might give it a whirl...

Anything to stabilise him...

[Rudi]

I propose an anti-spill cup, with a flywheel built into the base of the cup to provide gyroscopic stabilization. The basic model could use a string wrapped around the flywheel's axle, which you'd pull to spin it up. For additional cost, the deluxe model would have a rechargeable-battery-powered motor.

When/where can I buy one.

[HansV]

It's a Kitchen Table Science project for Jezza...

[Don Wells]

FWIW:

I have just tested a spinning body of water in a cylindrical container and found that when the container is tipped the surface of the water remains horizontal and the axis of the whirlpool remains vertical.

Conclusion: No benefit is derived from spinning the liquid in an open vessel.

[DaveA]

The far easier solution is not to drink tea

hard to spill out of a wine bottle

[BobArch2]

Here you go Buttercup... problem solved

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