[HN Gopher] Ketchup is a non-Newtonian fluid
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Ketchup is a non-Newtonian fluid
Author : pseudolus
Score : 24 points
Date : 2021-03-13 11:53 UTC (1 days ago)
(HTM) web link (www.scientificamerican.com)
(TXT) w3m dump (www.scientificamerican.com)
| User23 wrote:
| Also true for (some?) honey[1]. I remember learning about Ketchup
| and that, among many other things, from the Einstein Anderson
| books[2] when I was a child.
|
| [1]
| https://www.sciencedirect.com/science/article/abs/pii/S02608...
|
| [2] https://www.goodreads.com/series/101369-einstein-anderson
| simonblack wrote:
| Shake and shake
|
| The ketchup bottle.
|
| None'll come,
|
| And then a lot'll.
| DougN7 wrote:
| My Grandma said:
|
| Silly silly ketchup bottle
|
| First a little
|
| Then a lottle
|
| Same meaning :)
| lordgrenville wrote:
| I find this with some brands but not with others, so assumed it
| was a solved problem and some manufacturers are just cutting
| corners on bottle design. Is this not the case?
| devoutsalsa wrote:
| As someone who can use almost an entire bottle of Heinz 57 on
| an order of French fries, this made me laugh. Whenever I ask
| for ketchup at a restaurant and they bring me "only" 4 packets,
| I do my best not to roll my eyes in disappointment because I
| know how ridiculous I am.
| capableweb wrote:
| If I were you, I'd slow down with the ketchup alright, that
| sounds obsessively much. Consider that commercial ketchup
| tends to have lots of sugar and sodium.
| devoutsalsa wrote:
| It's alright. I'm balanced it out with a Diet Coke.
| kortilla wrote:
| Armchair nutrition advice on the internet, that's a first!
| What's next? Ice cream and cigarettes are bad!?!? The gall!
| carols10cents wrote:
| Through decades of experimentation, I have proven that hitting
| the 57 on the bottle is the best way to get the shearing force
| going.
| gerdesj wrote:
| Hold the bottle in one hand as normal and instead of hitting
| the back of it, hit the underside of your wrist instead ie
| hitting upwards not downwards.
|
| The bottle and the liquid are two "things" which are loosely
| connected together via "fluidy" friction etc. When you hit the
| back of the bottle, you are effectively trying to force the
| bottle around the ketchup that is trying to dribble out
| downwards. Gravity is trying to drag the ketchup out. The
| impact will make the ketchup a bit more liquid. Some ketchup
| will flow. We know it does because it does!
|
| When you make an impact upwards, then you are making the bottle
| try to leave the ketchup behind (inertia). Combine that with
| gravity and the impact liquidising the ketchup and more of the
| stuff comes out.
|
| There are other considerations such as the shape of the bottle.
| If you want the fastest deposition then probably something like
| a conical bottle with 45deg at the apex or whatever minimises
| internal surface area for a given contained volume. However
| that will dump an entire bottle in one go and you will impale
| your hand if you tap the back of it. It's quite a tough
| problem. The squeezy jobbies seem like a bit of a cop out
| somehow!
|
| Assume a spherical, infinite ketchup bottle. Be careful with
| your aim.
| halfmatthalfcat wrote:
| I've always heard this is by design.
| dheera wrote:
| > Ketchup is famous for being hard to get out of the bottle
|
| Whatever happened to that LiquiGlide stuff that was touted 10
| years ago? Why isn't it everywhere?
| thihguy wrote:
| Is solving the ketchup bottle problem like nuclear fusion, the
| solution is always 10 years away?
|
| The flexible plastic bottles mentioned in the article are just as
| bad, for some reason they make them very thick.
|
| Anyone know why ketchup doesn't come in a toothpaste like tube?
| That feels like it should work. What am I missing?
| monkey_monkey wrote:
| It's probably a sizing issue, given how much ketchup gets used,
| you'd need a lot of toothpaste tubes, and making them huge
| would lead the the same issues as you get with other
| containers.
| shriphani wrote:
| So we should be able to walk on the surface of a pool filled with
| ketchup?
|
| I've seen this video of people walking on custard on brainiac:
| https://www.youtube.com/watch?v=Iz9KnPZWOgs
| csunbird wrote:
| Braniac is back? I miss that show
| thihguy wrote:
| Unlikely - a spoon sinks in it.
| surround wrote:
| No, ketchup is shear-thinning, meaning it's _less_ solid when
| under stress.
| agumonkey wrote:
| I wonder if these properties are used in analog devices... I
| recently learned that ovens had thermal switches based on wax
| (and expansion under heat).
| klyrs wrote:
| https://en.wikipedia.org/wiki/Dilatant#Applications
|
| I'd say that shear thickening fluids as used in traction
| control systems can be seen as an analog clutch.
| thihguy wrote:
| The lock in a washing machine door works like that, which
| is why it takes two minutes to unlock.
| raverbashing wrote:
| Yes! And it's the opposite of oobleck. Meaning, it is shear-
| thinning (mayo is similar)
|
| There's also a 3rd category, the thixotropic fluids, they do
| become thinner with stresses but they take a while to solidify
| again
| _Microft wrote:
| Hmm, is it possible to add exactly so much corn starch to ketchup
| that the thinning and thickening effects cancel out?
|
| If it is then most likely only for a particular force applied
| because it seems unlikely that the effects are exactly opposite?
|
| Edit: it should have occured to me that combining ketchup with
| thickeners might be a well-researched topic in food science
| already.
| agumonkey wrote:
| Would make a magnificent youtube video.
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