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Liquid in Motion: Newsletter Challenge (March 2016)

Posted February 29, 2016 4:59 PM
Pathfinder Tags: challenge questions

This month's Challenge Question: Specs & Techs from IHS Engineering360:

Entering a laboratory, you notice a motionless clear cylinder resting on a table that is filled with a liquid circulating around inside. After hours of observation, you are puzzled to find that the liquid's motion has not changed. Knowing that no outside force or energy has entered the cylinder since you began observing, how is this possible?

And the answer is:

The liquid in the cylinder is superfluid helium-4.

Helium becomes a liquid when cooled to a temperature below its boiling point of 4.22 K (-268.93° C). Taken down a couple more degrees past its "lambda point" of 2.17 K (-270.98° C), liquid helium starts to exhibit unusual properties. It is at this point that a fraction of the helium has transitioned into a "superfluid." In this curious state of matter, the helium behaves like a fluid with zero viscosity. With no friction to slow its motion, the superfluid helium flows past the surface of the cylinder, continuing to circulate endlessly (or until it warms up and transitions back into its more regular liquid or gaseous states).

Unlike most liquids, helium doesn't turn into a solid when cooled down. Its atoms are light and weakly attracted to each other, so even when cooled to temperatures at which regular heat vibrations are absent, helium doesn't settle into a solid. At low temperatures its atoms wiggle with zero-point motion, a slight momentum bestowed by the quantum uncertainty principle. Instead of settling in a solid state, liquid helium undergoes a transformation known as Bose-Einstein condensation. Its atoms start acting in harmony, behaving like one big particle, no longer colliding together. It is these quantum effects that grant superfluids their remarkable properties.

For more on superfluid helium, including a detailed description of how superfluid helium is actually a mixture, with normal and superfluid components, see The physics of superfluid helium[pdf].

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#1

Re: Liquid in Motion: Newsletter Challenge (March 2016)

02/29/2016 5:11 PM

Superfluid (liquid) helium-4 has zero viscosity.

https://en.wikipedia.org/wiki/Superfluid_helium-4

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#2
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Re: Liquid in Motion: Newsletter Challenge (March 2016)

02/29/2016 6:16 PM

Add a little Marvel Mystery Oil to it and it would make a great penetrating oil. Cryogenically treats your nuts while you loosen them.

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#9
In reply to #2

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 2:14 AM

Sounds painful!!

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#10
In reply to #9

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 2:18 AM

If you don't like that sort of thing

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#25
In reply to #9

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 5:27 PM

Only when they thaw!

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#3

Re: Liquid in Motion: Newsletter Challenge (March 2016)

02/29/2016 6:24 PM

It is stated:

"...no outside force or energy has entered the cylinder since you began observing..."

So, no light can enter (or leave) the cylinder. No, wait, we're also told "...notice a motionless clear cylinder..."

And just how cold is it this room anyway?

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#4

Re: Liquid in Motion: Newsletter Challenge (March 2016)

02/29/2016 10:08 PM

Magnetic stirrer

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#5

Re: Liquid in Motion: Newsletter Challenge (March 2016)

02/29/2016 10:38 PM

You stated that nothing ENTERED the cylinder, but if some of the fluid is EXITING the cylinder, then Coriolis effect will cause the liquid to rotate. If you note the direction of rotation, you may infer whether the lab is in the Northern or Southern hemisphere.
https://en.wikipedia.org/wiki/Coriolis_force
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#6

Re: Liquid in Motion: Newsletter Challenge (March 2016)

02/29/2016 11:01 PM

The liquid has magnetic properties and there is a magnetic stirrer built into the table. This is no mystery.

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#7

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 1:29 AM

It's actually the room and your brain that is spinning around the axis of the cylinder

Or counterspinning, depending on the hemisphere

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#8

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 1:53 AM

This can't be possible unless the room is at the same temperature as the material in the cylinder.

If not, energy is entering the cylinder by means of conduction.

If there is a magnetic stirrer, electrical energy is entering and being transformed into mechanical energy, but this would be "outside force" you note in your challenge.

Unless the scenario is a black hole (and I don't think anyone knows what happens in there) the description violates the Second Law of thermodynamics.

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#11

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 2:57 AM

Possibly liquid crystal in the presence of a magnetic field.

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#13
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Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 4:43 AM

'Knowing that no outside force or energy has entered the cylinder since you began observing, how is this possible?' This rules out a magnetic stirrer, a magnetic field or electrical source, heat source or any other external influence.

Therefore, if this is indeed factual, the inertia would need to be generated within the liquid and it would be liquids and or chemical reactions, that react, break down and react again within the solution.

I assume there may also be a colour change when the reactions take place.

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#12

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 4:17 AM

There is a stirrer powered by a self contained power pack releasing energy within the cylinder. The problem does not state that no energy is being consumed, merely that it energy and force have not entered the cylinder during the observation period.

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#14

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 5:28 AM

"a table that is filled with a liquid circulating around inside"

The magnetic stirrer is acting on the liquid in the table.

Energy entering or leaving the cylinder, and, the cylinder itself are completely irrelevant.

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#15
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Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 6:02 AM

''....cylinder, (resting on a table), that is filled with a liquid circulating......''

The joys of punctuation, and the lack thereof, allowing ambiguity and interpretation of each person.

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#37
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Re: Liquid in Motion: Newsletter Challenge (March 2016)

04/06/2016 8:11 AM

I was wondering if anyone else had spotted that....I keep telling you that grammar is important...

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#38
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Re: Liquid in Motion: Newsletter Challenge (March 2016)

04/06/2016 8:26 AM

Not here, anything goes it seems. And oddly, others assume understandings. How do they manage?

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#16

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 8:18 AM

The liquid is a 'ferrofluid' and the cylinder is sitting on a magnetic stirrer.

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#17

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 9:26 AM

Ferro fluid and a rotating magnet beneath the table.

Sorry USB i should read the responses before i post.

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#18

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 9:59 AM

The liquid is in outer space. The liquid is still while the container and the "room" (space station), and observer spins around it.

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#19

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 11:10 AM

...a trick question maybe...? No external force or energy has entered - no magnetic stirrers then.

I guess an internal battery powered spinning device device was put before you started watching.

No clues to what the liquid is, or how fast it is spinning - assuming horizontal - but it could be vertical - a form of cooling by heat transfer with energy leaving the cylinder setting up in internal rise and fall current due to change in density - or a change in pressure due to liquid leaving the cylinder.

But I like the idea of a 'spinning' room where you are turning - and not the cylinder. Or the space lab.

#5, 7, 12 & 13 could be pointing in the right direction.....

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#20

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 12:35 PM

a circling catalytic chemical reaction

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#21

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 1:06 PM

The liquid in the container is on a spinning planet, which is also orbiting a star

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#27
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Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 9:32 PM

Isn't Earth a spinning planet which orbit the Sun?

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#22

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 1:09 PM

I think superfluidity is the answer. I have a hard time imagining it but it's like superconductivity except molecules instead of electrons. Welcome to the quantum world.

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#23

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 2:09 PM

https://en.wikipedia.org/wiki/Electrostatic_fluid_accelerator

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#24

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 3:17 PM

It is indeed liquid helium as Rixter has stated. The cylinder is perfectly insulated and the helium was stirred before "you" got into the room.

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#26

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 6:42 PM

Belousov Zhabotunsky reaction. Ferroin changing due to how many molecules are attached to it.

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#28

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/01/2016 10:09 PM

The liquid is a nourishing soup - or just Detroit tapwater - in which a fly is swimming in a clockwise circle. The reaction force sends the soup anticlockwise.

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#29

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/15/2016 11:07 AM

After painting with silver aluminum paint and cleaning the brush in gasoline, later in the afternoon I was fascinated to see the liquid in the can rolling up in the center and down at the sides.

I assume this was evaporation cooling the surface causing a thermal cycle. Not sure how you would see this in clear liquid but I know from personal experience it happens.

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#30

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/15/2016 4:52 PM

Reading this it does not say how the clear cylinder is resting on the table so lets put it sidways so its axis is parallel to the table. Then lets heat up the one side with a flame or some heat source whatever. Maybe also cool the oposite side with ice or a heatsink or fan or what ever. The liquid now rotates in a cirular motion due to hot liquids rising and cold liquids sinking but circulates horizontaly.

problem solved

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#31
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Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/15/2016 6:01 PM

"Knowing that no outside force or energy has entered the cylinder since you began observing".

"[H]eat up the one side".

Problem NOT solved

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#32
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Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/16/2016 8:51 PM

As I see it its a trick question. Outside force means no one using a magnetic spinner or such. Energy ok well lets say it was not a noticeable energy such as the sun coming through the window heating it up on the one side. This way no one has noticeable put energy into it.

As I see it nothing can go on moving indefintely, there is always friction even in liquids. The question uses the words "noticable energy". This is the best I can think of.

You got anything?

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#34
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Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/17/2016 1:04 PM

no outside force or energy has entered the cylinder since you began observing

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#33

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/17/2016 6:10 AM

So what in fact happened to the posting of the answer?

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#35

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/17/2016 6:10 PM

"Knowing that no outside force or energy has entered the cylinder since you began observing" Actually you fell asleep "After hours of observation" and some gave it a good stir .....!

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#36

Re: Liquid in Motion: Newsletter Challenge (March 2016)

03/30/2016 8:52 PM

Beer brewing in a clear glass flask swirls for hours under the heat generated by bacterial action...

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#39

Re: Liquid in Motion: Newsletter Challenge (March 2016)

04/10/2016 6:16 AM

After hours of observation

Observation needs energy (visible light?) that heat's up the liquid helium so that the liquid will loose its superfluid state.

br

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#40

Re: Liquid in Motion: Newsletter Challenge (March 2016)

04/10/2016 9:18 PM

"After hours of observation..."

Your explanation is correct, but the above condition calls into question even the possibility of such an occurrence.

The situation you describe is possible if the room is quite cold, and having not noted anything about room temperature is somewhat analogous to stating that the sun will not rise tomorrow, but not noting that you are referring to the roughly 6 month night at the poles.

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