What-If 0036: "Cornstarch"

What if there was a forum for discussing these?

Moderators: Moderators General, Prelates, Magistrates

User avatar
rhomboidal
Posts: 797
Joined: Wed Jun 15, 2011 5:25 pm UTC
Contact:

What-If 0036: "Cornstarch"

Postby rhomboidal » Tue Mar 12, 2013 4:17 pm UTC

http://what-if.xkcd.com/36

I much prefer the term "goop" to "non-Newtonian fluid."

richP
Posts: 195
Joined: Wed Aug 17, 2011 3:28 pm UTC

Re: What-If 0036: "Cornstarch"

Postby richP » Tue Mar 12, 2013 4:23 pm UTC

I can't decide if cornstarch girl would be a lot of fun, or incredibly boring. I do know that she'd be one extreme or the other.

User avatar
peewee_RotA
Posts: 504
Joined: Mon Dec 12, 2011 1:19 pm UTC

Re: What-If 0036: "Cornstarch"

Postby peewee_RotA » Tue Mar 12, 2013 4:30 pm UTC

"be careful of the broken glass while you're being swept out through the window"

be careful of the free glass while you're being swept out through the window"


Fixed it!
"Vowels have trouble getting married in Canada. They can’t pronounce their O’s."

http://timelesstherpg.wordpress.com/about/

Vroomfundel
Posts: 117
Joined: Wed Sep 29, 2010 7:36 am UTC

Re: What-If 0036: "Cornstarch"

Postby Vroomfundel » Tue Mar 12, 2013 4:42 pm UTC

Am I the only one that cringes at the sight of the ruined speaker :-\ I guess there aren't many bassheads around
lexicum.net - my vocabulary learning platform

mishka
Posts: 49
Joined: Mon Mar 28, 2011 3:47 am UTC

Re: What-If 0036: "Cornstarch"

Postby mishka » Tue Mar 12, 2013 5:04 pm UTC

Is snow a liquid or a solid? How is it different from an avalanche of molasses?

User avatar
styrofoam
Posts: 256
Joined: Sat May 08, 2010 3:28 am UTC

Re: What-If 0036: "Cornstarch"

Postby styrofoam » Tue Mar 12, 2013 5:18 pm UTC

mishka wrote:Is snow a liquid or a solid?

Snow is a solid. It's a powder made of very fine crystals.
aadams wrote:I am a very nice whatever it is I am.

User avatar
Moose Anus
Posts: 432
Joined: Fri Oct 14, 2011 10:12 pm UTC

Re: What-If 0036: "Cornstarch"

Postby Moose Anus » Tue Mar 12, 2013 5:21 pm UTC

mishka wrote:How is it different from an avalanche of molasses?
It's sugar free!
Lemonade? ...Aww, ok.

User avatar
peewee_RotA
Posts: 504
Joined: Mon Dec 12, 2011 1:19 pm UTC

Re: What-If 0036: "Cornstarch"

Postby peewee_RotA » Tue Mar 12, 2013 5:33 pm UTC

Moose Anus wrote:
mishka wrote:How is it different from an avalanche of molasses?
It's sugar free!

And it flows in January.
"Vowels have trouble getting married in Canada. They can’t pronounce their O’s."

http://timelesstherpg.wordpress.com/about/

Mike Rore
Posts: 19
Joined: Wed Dec 05, 2012 4:18 pm UTC

Re: What-If 0036: "Cornstarch"

Postby Mike Rore » Tue Mar 12, 2013 5:59 pm UTC

I guess this what-if renews my hope that someday my question is going to be featured.

Someday, Mike... someday.

Damon
Posts: 6
Joined: Mon Jul 16, 2007 2:46 pm UTC

Re: What-If 0036: "Cornstarch"

Postby Damon » Tue Mar 12, 2013 6:05 pm UTC

I had to follow the link to the Boston Molasses Flood, which led to the London Beer Flood. Amazing stuff!

Zinho
Posts: 102
Joined: Fri Apr 08, 2011 3:23 pm UTC

Re: What-If 0036: "Cornstarch"

Postby Zinho » Tue Mar 12, 2013 6:40 pm UTC

@Vroomfundel: Was there an earlier version that I missed where a bass speaker is shown? I don't see one in this comic.

mishka wrote:Is snow a liquid or a solid? How is it different from an avalanche of molasses?

That depends on what you mean by solid. The snow crystals at or below the freezing point of water are definitely solid. A snow bank on the side of a mountain may, however, be a mixture of frozen snow and some meltoff; whether you call this mixture "snow" or "slush" is a value judgement that I'm not sure has a good dividing line (when between 0 and 100 deg C does a pot of water become "hot"?).

Both a snow bank in an avalanche and cornstarch mixed into oobleck fall better into the category of "fluids" better than they do the phases of matter called "liquid" and "solid". Note that air is a fluid as well, and that fluidity is defined as deforming continuously under a shear stress. The snow bank won't start to deform until it reaches some critical stress threshold, then the agitation of tumbling down the hill reduces its viscosity; this combination of properties is called thixotropy. In contrast, the oobleck is a shear-thickening fluid, offering more resistance to flow as more stress is applied.

Since the molasses is shear thinning I'd guess that an avalanche of snow would act similarly to the Boston Molasses Flood at their respective scales. Both have an initial event that triggered the flow (the silo failing, in the case of the molasses), and both are shear-thinning so they'd have similar flow. The end of an avalanche, though, is probably more abrupt as the snow transitions back to a compact state; once the shear force (weight of snow on a slope) falls below a certain point it'll stop flowing. In contrast the molasses would continue to flow slowly as long as there is any slope to provide shear stress.

Comparing either to the oobleck sounds like a job for the Mythbusters; the trick would be wording it so that it sounds like they have something to debunk (instead of just "I'd love to see this happen"). Any wordsmiths want to take that on and submit it to Discovery Channel? :D

User avatar
keithl
Posts: 659
Joined: Mon Aug 01, 2011 3:46 pm UTC

Re: What-If 0036: "Cornstarch"

Postby keithl » Tue Mar 12, 2013 6:53 pm UTC

Uh - toilet outflows are not valved. Fill an ordinary flush toilet to the brim with any liquid, and it will drain down until it is level with top of the trap. Indeed, you must pour liquid in very rapidly to even reach the rim of an unplugged toilet.

Image

The "sucking, flushing" action is because once a bolus of water starts down the outlet drain pipe, it will pull a slight vacuum behind it, syphoning more water. Oobleck won't go down the pipe very fast, so it won't "flush", but it will nevertheless level off below the top of the toilet bowl while continuing to pour down the drain.

However, before the oobleck gets as high as the rim of the toilet bowl, it will leak out of the house through the door sills, probably never getting more than an inch deep on the floor. Related tip: do not leave the water running in the bathtub and fall asleep. Related tip number 2: do not keep servers in the basement below the bathtub.

EvanED
Posts: 4331
Joined: Mon Aug 07, 2006 6:28 am UTC
Location: Madison, WI
Contact:

Re: What-If 0036: "Cornstarch"

Postby EvanED » Tue Mar 12, 2013 8:18 pm UTC

Zinho wrote:Comparing either to the oobleck sounds like a job for the Mythbusters; the trick would be wording it so that it sounds like they have something to debunk (instead of just "I'd love to see this happen"). Any wordsmiths want to take that on and submit it to Discovery Channel? :D
"Myth: Comparing things to oobleck would not be awesome"

ricketybridge
Posts: 31
Joined: Tue Dec 04, 2012 8:34 pm UTC

Re: What-If 0036: "Cornstarch"

Postby ricketybridge » Tue Mar 12, 2013 9:09 pm UTC

I totally thought oobleck was some bullshit my elementary school teacher thought up when she couldn't think of anything else to do.

BunsenH
Posts: 24
Joined: Fri Jun 24, 2011 2:43 pm UTC

Re: What-If 0036: "Cornstarch"

Postby BunsenH » Wed Mar 13, 2013 2:03 am UTC

A bathtub full of oobleck is a lot of fun. It was one of the unofficial attractions sponsored by a convention committee in charge of random weird stuff at a couple of Minicons.

You can jog on the spot on it, but if you stand still, you start to sink, much as one would in quicksand. If you can hold one foot still (sinking slowly) while pulling upwards with and jiggling the other, one can vibrate the other foot free; then swap foot actions, and alternate until both feet are free enough to start jogging again.

Lots of towels for the floor are highly recommended.

Disposal of the material afterwards led to complications: http://gerisullivan.livejournal.com/78702.html.

blowfishhootie
Posts: 486
Joined: Wed Sep 21, 2011 11:13 pm UTC

Re: What-If 0036: "Cornstarch"

Postby blowfishhootie » Wed Mar 13, 2013 3:01 am UTC

I think this week's what-if was more interesting when it just wasn't posted. I predict the end of what-if before June - and if it's not done by June, I predict it should be.

User avatar
Bernkastel
Posts: 13
Joined: Fri Nov 30, 2012 9:04 am UTC

Re: What-If 0036: "Cornstarch"

Postby Bernkastel » Wed Mar 13, 2013 5:56 am UTC

No, the local officials would not shut off your water, or anything like that. After all, it's not unpleasant; it's fun!

It really only starts when you get outside the house.

User avatar
Angelastic
Posts: 700
Joined: Thu Nov 03, 2011 8:36 am UTC
Location: .at (let's see what's through here!)
Contact:

Re: What-If 0036: "Cornstarch"

Postby Angelastic » Wed Mar 13, 2013 8:30 am UTC

Hmm, that's weird; one of the comments on BunsenH's blog mentions someone with the same name as someone I know. I wonder if it's the same person.

As for the what-if, I was disappointed that the non-Newtonian nature of oobleck was not mentioned later in the article; nothing about walking around at various speeds in a house knee-deep in oobleck. No unexpected effects of its movement around the house/out the window.
Knight Temporal, and Archdeacon of buttermongery and ham and cheese sandwiches. Nobody sells butter except through me.
Image Smiley by yappobiscuits. Avatar by GLR, buffygirl, BlitzGirl & mscha, with cari.j.elliot's idea.
Haiku Detector
starts a trend to make way for
my robot army.

User avatar
peewee_RotA
Posts: 504
Joined: Mon Dec 12, 2011 1:19 pm UTC

Re: What-If 0036: "Cornstarch"

Postby peewee_RotA » Wed Mar 13, 2013 10:19 am UTC

BunsenH wrote:A bathtub full of oobleck is a lot
Disposal of the material afterwards led to complications: http://gerisullivan.livejournal.com/78702.html.


Scooping slowly into an nearby sink with a steady water flow wasn't an option?
"Vowels have trouble getting married in Canada. They can’t pronounce their O’s."

http://timelesstherpg.wordpress.com/about/

BunsenH
Posts: 24
Joined: Fri Jun 24, 2011 2:43 pm UTC

Re: What-If 0036: "Cornstarch"

Postby BunsenH » Wed Mar 13, 2013 3:29 pm UTC

angelastic: one of the comments on BunsenH's blog mentions someone with the same name as someone I know

Just for clarity: the blog I linked to isn't my blog, though I do have an LJ which I post to occasionally (http://bunsen-h.livejournal.com). At any rate, fandom being what it is with a lot of metaphorical Venn-diagram circles intersecting, I wouldn't be surprised if it was the same person.

peewee_RotA: Scooping slowly into an nearby sink with a steady water flow wasn't an option?

When I heard the story, I wondered about that as well. A single sink would probably have taken too long, but I'm pretty sure that they had access to several sinks, bathtubs, etc., and it would probably have been less trouble than the bucket brigade down to the sewer outside the hotel which was, IIRC, the ultimate solution. I don't know what the failed "Plans B, C, and on" involved.

User avatar
peewee_RotA
Posts: 504
Joined: Mon Dec 12, 2011 1:19 pm UTC

Re: What-If 0036: "Cornstarch"

Postby peewee_RotA » Wed Mar 13, 2013 4:08 pm UTC

BunsenH wrote:angelastic: one of the comments on BunsenH's blog mentions someone with the same name as someone I know

Just for clarity: the blog I linked to isn't my blog, though I do have an LJ which I post to occasionally (http://bunsen-h.livejournal.com). At any rate, fandom being what it is with a lot of metaphorical Venn-diagram circles intersecting, I wouldn't be surprised if it was the same person.


While we're on the subject of you, have you ever purchased a pre-paid phone and threw it away a week later?
"Vowels have trouble getting married in Canada. They can’t pronounce their O’s."

http://timelesstherpg.wordpress.com/about/

User avatar
orthogon
Posts: 3078
Joined: Thu May 17, 2012 7:52 am UTC
Location: The Airy 1830 ellipsoid

Re: What-If 0036: "Cornstarch"

Postby orthogon » Wed Mar 13, 2013 4:48 pm UTC

BunsenH wrote:angelastic: one of the comments on BunsenH's blog mentions someone with the same name as someone I know

Just for clarity: the blog I linked to isn't my blog, though I do have an LJ which I post to occasionally (http://bunsen-h.livejournal.com). At any rate, fandom being what it is with a lot of metaphorical Venn-diagram circles intersecting, I wouldn't be surprised if it was the same person.


Don't say it. Don't say it.

Spoiler:
Don't you mean an Euler diagram? That the circles intersect tells us nothing if it's a Venn diagram.

Damn, I said it. And this time last week I'd never even heard of an Euler diagram. Truly, pedantry is like entropy.
xtifr wrote:... and orthogon merely sounds undecided.

BunsenH
Posts: 24
Joined: Fri Jun 24, 2011 2:43 pm UTC

Re: What-If 0036: "Cornstarch"

Postby BunsenH » Wed Mar 13, 2013 4:54 pm UTC

peewee_RotA: While we're on the subject of you, have you ever purchased a pre-paid phone and threw it away a week later?

Uh, no, why do you ask?

For future experimenters with oobleck: I'd like to point out that the analysis of the problem in the blog — "That much oobleck under the pressure of even a thin film of water resembles nothing so much as concrete" — is incorrect. Modest static pressure doesn't make oobleck any more or less tractable, though the buoyancy of the water might make the oobleck a bit more difficult to control. (If the pressure + temperature + time combination is high enough to let the starch particles soften and stick to each other, on the other hand, you might as well just give up and start wishing for the Amylase Fairy.) You can scoop it, if you move slowly, and jiggling your scoop will make the oobleck more fluid.

The best solution to the problem that I can think of (admittedly untested) would be something like a caisson, large enough to encompass the bathtub faucet and the drain, and also large enough to let the contents of the caisson be scooped out initially. Then start the tub faucet running, and let the oobleck flow very slowly into the caisson, with good mixing.

User avatar
peewee_RotA
Posts: 504
Joined: Mon Dec 12, 2011 1:19 pm UTC

Re: What-If 0036: "Cornstarch"

Postby peewee_RotA » Wed Mar 13, 2013 5:06 pm UTC

BunsenH wrote:peewee_RotA: While we're on the subject of you, have you ever purchased a pre-paid phone and threw it away a week later?

Uh, no, why do you ask?


T'would be Bunsen's Burner phone.



Another option is to place an amp directly next to the tub and crank up the volume. As the oobleck evacuates, mop it up. Rinse the rest down the drain.
"Vowels have trouble getting married in Canada. They can’t pronounce their O’s."

http://timelesstherpg.wordpress.com/about/

naj
Posts: 3
Joined: Mon Mar 07, 2011 6:17 am UTC

Re: What-If 0036: "Cornstarch"

Postby naj » Wed Mar 13, 2013 5:13 pm UTC

Related works: Mythbusters http://www.youtube.com/watch?v=5GWhOLorDtw and Brainiac http://www.youtube.com/watch?v=BN2D5y-AxIY.
Mythbusters are actually using cornstarch, but not really a pool. Brainiac use a proper garden swimming pool :)

User avatar
bmonk
Posts: 662
Joined: Thu Feb 18, 2010 10:14 pm UTC
Location: Schitzoed in the OTT between the 2100s and the late 900s. Hoping for singularity.

Re: What-If 0036: "Cornstarch"

Postby bmonk » Wed Mar 13, 2013 9:20 pm UTC

blowfishhootie wrote:I think this week's what-if was more interesting when it just wasn't posted. I predict the end of what-if before June - and if it's not done by June, I predict it should be.

Clearly another case where we need to apply more power to see how interesting an explosion we can produce.
Having become a Wizard on n.p. 2183, the Yellow Piggy retroactively appointed his honorable self a Temporal Wizardly Piggy on n.p.1488, not to be effective until n.p. 2183, thereby avoiding a partial temporal paradox. Since he couldn't afford two philosophical PhDs to rule on the title.

rmsgrey
Posts: 3631
Joined: Wed Nov 16, 2011 6:35 pm UTC

Re: What-If 0036: "Cornstarch"

Postby rmsgrey » Wed Mar 13, 2013 9:59 pm UTC

bmonk wrote:
blowfishhootie wrote:I think this week's what-if was more interesting when it just wasn't posted. I predict the end of what-if before June - and if it's not done by June, I predict it should be.

Clearly another case where we need to apply more power to see how interesting an explosion we can produce.


Powdered cornstarch in air makes a reasonably explosive mixture...

User avatar
Locoluis
Posts: 102
Joined: Mon Dec 11, 2006 7:30 pm UTC
Location: Santiago, Chile
Contact:

Re: What-If 0036: "Cornstarch"

Postby Locoluis » Thu Mar 14, 2013 1:03 am UTC

richP wrote:I can't decide if cornstarch girl would be a lot of fun, or incredibly boring. I do know that she'd be one extreme or the other.


Have you heard about the Cornchip Girl from "Recess"? http://recess.wikia.com/wiki/Cornchip_Girl

I bet she's like that, only all grown up.
Sueños del Sur - A webcomic about four siblings, their family, friends, adventures and dreams.
http://sds.lgm.cl/

moops
Posts: 10
Joined: Thu Aug 11, 2011 10:03 pm UTC

Re: What-If 0036: "Cornstarch"

Postby moops » Thu Mar 14, 2013 3:08 am UTC

That did not go NEARLY far enough.


more oobleck. MUCH more. I want to observe the effects of a planet with a 3000 mile deep layer of oobleck.

User avatar
Davidy
Posts: 221
Joined: Sat Dec 01, 2012 1:18 am UTC

Re: What-If 0036: "Cornstarch"

Postby Davidy » Thu Mar 14, 2013 5:41 am UTC

rmsgrey wrote:
Powdered cornstarch in air makes a reasonably explosive mixture...


Almost *anything* powdered in air makes a reasonably explosive mixture. Ref silo explosions, etc. We used to put a candle in an upside down Charles Chips can and use a long rubber tube to blow flour into the can. The explosion would send the can 10 feet high.
"It's only funny until someone loses an eye, then it's still funny but they can only see it in 2-D."

BunsenH
Posts: 24
Joined: Fri Jun 24, 2011 2:43 pm UTC

Re: What-If 0036: "Cornstarch"

Postby BunsenH » Fri Mar 15, 2013 3:39 pm UTC

moops wrote:more oobleck. MUCH more. I want to observe the effects of a planet with a 3000 mile deep layer of oobleck.


At the bottom, the combination of heat and pressure drive off volatiles, leaving coal.

At the top, fermentation produces vast amounts of ethanol and CO2. We get a runaway greenhouse effect that destroys all life on the planet.

Everybody dies. Oh, the embarrassment.

User avatar
addams
Posts: 10268
Joined: Sun Sep 12, 2010 4:44 am UTC
Location: Oregon Coast: 97444

Re: What-If 0036: "Cornstarch"

Postby addams » Fri Mar 15, 2013 4:03 pm UTC

styrofoam wrote:
mishka wrote:Is snow a liquid or a solid?

Snow is a solid. It's a powder made of very fine crystals.


That is what 'they' say.
'They' also say, 'When it 'sets up', it is hard as concrete.'

Sometimes.

Spoiler:
http://en.wikipedia.org/wiki/Avalanche#Powder_snow_avalanches


Spoiler:
Hold hands and stick together. The lands of Snow are very, very quiet, sometimes.
Then there is a loud noise. That is what 'They' say.


by naj » Wed Mar 13, 2013 9:13 am UTC

Related works: Mythbusters http://www.youtube.com/watch?v=5GWhOLorDtw and Brainiac http://www.youtube.com/watch?v=BN2D5y-AxIY.
Mythbusters are actually using cornstarch, but not really a pool. Brainiac use a proper garden swimming pool

It is all about that second clip.
Spoiler:
The second clip is so funny. At 2:17 into the clip is where, "The Math was Wrong? How Wrong?"

How Much fun and How Dangerous is that stuff?
I would want to get into it. How did those people stay out?

Self control? What about the After Party?
Two rescue people for each three swimmers? Right?

Rules! That stuff is dangerous.
Mud and sand do that, too.

The more dangerous a thing is the more rules that thing needs. Right?
Of course, some things are so dangerous; Learning 'The Rules' only helps amateurs.


Can you think of One Example? One Example where Learning 'The Rules' only helps amateurs?
Life is, just, an exchange of electrons; It is up to us to give it meaning.

We are all in The Gutter.
Some of us see The Gutter.
Some of us see The Stars.
by mr. Oscar Wilde.

Those that want to Know; Know.
Those that do not Know; Don't tell them.
They do terrible things to people that Tell Them.

Kit.
Posts: 1117
Joined: Thu Jun 16, 2011 5:14 pm UTC

Re: What-If 0036: "Cornstarch"

Postby Kit. » Fri Mar 15, 2013 5:54 pm UTC

Angelastic wrote:As for the what-if, I was disappointed that the non-Newtonian nature of oobleck was not mentioned later in the article; nothing about walking around at various speeds in a house knee-deep in oobleck. No unexpected effects of its movement around the house/out the window.

Nothing about dropping a playing boombox into a roomful of oobleck...

User avatar
Pfhorrest
Posts: 5447
Joined: Fri Oct 30, 2009 6:11 am UTC
Contact:

Re: What-If 0036: "Cornstarch"

Postby Pfhorrest » Fri Mar 15, 2013 6:32 pm UTC

Transport now to a science lab
Where the students complain that all their projects are drab
The experiments are boring, just made of lose
Except for these weird non-Newtonian goos.

And so I brought my boombox, from back at my pad
And what happened next was totally rad!

Oobleck went flying everywhere!
The physics were unintuitive
A bunch of corn starch and water dancing
It was messy to say the least

Oh! A boombox can change the world
You gotta know your limits with a boombox
This was a cautionary tale
A boombox is not a toy!
Forrest Cameranesi, Geek of All Trades
"I am Sam. Sam I am. I do not like trolls, flames, or spam."
The Codex Quaerendae (my philosophy) - The Chronicles of Quelouva (my fiction)

webgiant
Posts: 252
Joined: Mon Aug 17, 2009 5:36 pm UTC

Re: What-If 0036: "Cornstarch"

Postby webgiant » Sat Mar 16, 2013 9:01 pm UTC

Vroomfundel wrote:Am I the only one that cringes at the sight of the ruined speaker :-\ I guess there aren't many bassheads around

I started preemptively cringing when I read Randall's "It depends what you consider unpleasant." Randall seems to have a gift for coming up with entirely new things which are unpleasant, all within the parameters of whatever science he's using this week in the "What If?" column.

User avatar
Himself
Posts: 157
Joined: Sat Aug 27, 2011 4:17 am UTC

Re: What-If 0036: "Cornstarch"

Postby Himself » Sun Mar 17, 2013 2:55 am UTC

BunsenH wrote:
At the bottom, the combination of heat and pressure drive off volatiles, leaving coal.


I did a quick calculation using the density of water (I think oobleck is denser) and found that pressure at a depth would be about 47 gigpascals which I believe is more than enough to produce diamond.
"Looking me am a civilization person"
-Ratio Tile

BunsenH
Posts: 24
Joined: Fri Jun 24, 2011 2:43 pm UTC

Re: What-If 0036: "Cornstarch"

Postby BunsenH » Sun Mar 17, 2013 7:22 pm UTC

Himself wrote:
BunsenH wrote:
At the bottom, the combination of heat and pressure drive off volatiles, leaving coal.


I did a quick calculation using the density of water (I think oobleck is denser) and found that pressure at a depth would be about 47 gigpascals which I believe is more than enough to produce diamond.


Oobleck is definitely denser than water (since added water sits on top of it), and 47 GPa is high enough pressure that diamond is the stable phase (a phase diagram is at http://pchemblog.umwblogs.org/2011/10/30/phase-diagram/). It looks like it's high enough pressure that graphite isn't even metastable.


Return to “What If?”

Who is online

Users browsing this forum: No registered users and 7 guests