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[deleted]

“The middle match is using the force from the bottle to push the other match up so it all evens out, the bottle is basically keeping itself up,”


[deleted]

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kdawgster1

Thank you, that is the last detail I was missing. I was looking at this thinking “I have a masters degree in mechanical engineering. Why can’t I figure this out!” Didn’t notice the match stick angle due to the camera perspective


netwoodle

I was thinking, "I am a window licking moron, but I don't believe in magic." I can kind of understand match stick angle.


n4bb

I was thinking “I’m a ape degen this must totally be magic”


Maguffins

*agrees in cave painting


useless_rejoinder

I screamed and threw a rock at the phone.


theRealGleepglop

I screamed and threw my phone at a rock.


ClarenceWorley47

I rocked and screamed a phone at my throw


itsanendless

I threw up rocks and my phone screamed


DisabledHarlot

I screwed a rock.


Johnsus_Christ

my phone screamed and threw up rocks at me


DrewBirdBlue

This one made me cackle, take this gift!


4x4Welder

I phoned and threw a scream at a rock.


subjectmatterexport

iPhone you scream we all rock for ice cream


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shoulda_been_gone

Ha, awesome


KarlMarxFarts

I was thinking “ooga ooga booga “


FracturedEel

I have a masters in match stick angles


Rhameolution

I was thinking it was going to light on fire 🔥


TheBlacktom

Physics and engineering is not that hard when demonstrated with match sticks. Problem is, usually they don't demonstrate just write bullshit on paper. Plus lots of stuff cannot be demonstrated by match sticks.


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Masothe

Dang so much for that person's masters degree in mechanical engineering


StoneHolder28

I only have a bachelor's in engineering and work experience as a structural engineer, but the center if gravity explanation is definitely the right one. The middle match holding everything up doesn't even make sense, you'd have to think the horizontal match is somehow fixed in midair.


dpzblb

Correct me if I’m wrong, but from my understanding, the lever explanation should be the right one. The two sides of the string are in tension and want to return to the original position, so the bottom horizontal match is in compression. This match is being held in place mostly due to friction, as the compression forces lead to a high normal force. At the same time, the string is pulling down on the top match. Thus, the strings are pulling down on the top match. However, the vertical match is also being put in compression due to the strings pulling down the top match and holding the bottom match, so it resists the top match and pushes back on it. Thus, the vertical match is pushing up on the top match. Since the downward from the string is located between the upward force from the vertical match and the pivot at the edge of the table, this becomes a lever. Finally, even though net downward force is clearly greater, since the vertical match is acting further from the pivot point than the strings, the net torque around the pivot point is zero. The main logical obstacle I have with the center of gravity argument is that if you reduce the bottle, string, and additional masses as a single point mass, the center of gravity of the whole system should not have drastically changed from the original situation. In particular, the center of mass of the entire bottle, string, and match system should be off the desk, making it fall.


Strawberry_Left

Have a look at [this video](https://youtu.be/3kX24bf7Xlg?t=92) for an extreme example of how the vertical stick alters the centre of gravity. The centre of gravity must be directly under the edge of the table. In the video posted here by OP, the centre of gravity is half the thickness of the string away from the edge of the table. When the vertical match is inserted, it pushes the weight half the string width under the edge of the table, so the weight is directly under the edge. If it was away from the edge, even by half the string thickness, then it wouldn't be in balance.


ExcitingAmount

Really, it's both. You can do the FBD to see where all the forces are, specifically the upward force from the angled match cancelling the moment from the couple formed by the downward force of the bottle and the upward force from the table, but ultimately the matches are just forming a hook. The CoG doesn't have to move much since the string is so close to the table, but in any static system all the forces eventually have to cancel out, and the only way for that to happen is for the CoG to be under a supported area.


StoneHolder28

The levers explanation can never work out if you ever try to apply actual values to it. I get why the logic is appealing but when you break down the trig it doesn't work that way. The issue you say you have is actually why this works. You're right it doesn't move drastically, because the center of mass is already very close to where it needs to be. But it does start off the desk and it does actually start "falling." This is what moves the center of mass. The big "lie" of this trick is in making people this it was always a static problem. But it isn't; the system starts as dynamic.


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LordSyriusz

External forces (gravity and reaction from table) need to even out. No matter what forces are between matches, they cannot even out external forces. And only way the external forces can even out is for center of gravity to be below table. If it would be possible to to even out external forces with internal, then it would be possible to lift the chair you are sitting on. That's what he meant with fixed match, it cannot produce external force, not that it cannot be held with tension. And I'm engineer too, it's almost like we learnt those things...


Strawberry_Left

Have a look at [this video](https://youtu.be/3kX24bf7Xlg?t=92) for an extreme example of how the vertical stick alters the centre of gravity. The centre of gravity must be directly under the edge of the table. In the video posted here by OP, the centre of gravity is half the thickness of the string away from the edge of the table. When the vertical match is inserted, it pushes the weight half the string width under the edge of the table, so the weight is directly under the edge. If it was away from the edge, even by half the string thickness, then it wouldn't be in balance.


CallieCallie86

Masters in physics here. At first all the force is pointing downwards, once the other two matches are added, the force is split into two, one pointing diagonally to the left and other pointing diagonally to the right. This splits up the force into three sections, left, right, and a small downward. The left and right force cancels out. When in doubt, draw free body diagram.


StoneHolder28

Maybe you were just unclear, but at no point is the downward force reduced. It actually increases. You can even see this happen if you use a flimsier material like cotton swabs, where the top swab bends more when you add the other two because the extra tension pulls down more at the string but now there's some rigidity added where the vertical meets the top.


AmoebaMan

Masters is correct. Guy you’re replying to is either an ignoramus or not communicating effectively.


ScenicFrost

>the system isn't in equilibrium Bro it's not moving lmao it is definitely in equilibrium. This is a very standard problem in Statics. You're being super /r/confidentlyincorrect my man.


AmoebaMan

It’s not incorrect. Maybe incomplete, but it’s correct. Also, if you’re going to try to explain something about a construct involving three different matches, I highly recommend you be more specific than “the match.” Especially since you’re coming out of the gate saying center of gravity doesn’t matter, which makes you sound like a dunce.


[deleted]

You didn't do a free body diagram and solve it all? What, are you one of those engineers with a social life?


Cat_Marshal

I feel judged because I am an engineer browsing Reddit on a Saturday and I did a rough diagram in my mind before coming to the comments.


_lablover_

As a physics PhD I did the same thing. A quick diagram in my head and convinced myself that it would shift the center of gravity under the table


Cat_Marshal

It’s not center of gravity, it’s cancellation of forces.


_lablover_

It's center of gravity and counteracting moments. But center of gravity must end up beneath the bench or the whole system would fall


StoneHolder28

These videos pop up fairly often here. Most people will never change their minds. I'm digging through the comments until I find the inevitable "they used glue" comment. There's always at least one.


_lablover_

I already saw 2 that claimed magnets lol


shill_ouster

It's both. Gravity exerts a force, hence where it is applied will affect the cancellation of forces to use your language.


[deleted]

The first time I saw this I did the same and then googled for an FBD because I was too lazy to do it. But I'm not only a civil, but focused in geotech. So we just make it all up anyway. Oh this equation almost our entire discipline is based on? Yeah, that's wrong. But it works, so fuck it.


celluj34

Three body?


[deleted]

I was considering it lol


[deleted]

How do you know if someone’s an engineer? They’ll tell you


kdawgster1

Oh wow, I love that one! You mind if I steal it?


AbortedBaconFetus

>Why can’t I figure this out!” Didn’t notice the match stick angle due to the camera perspective This is intentionally recorded from this view so you can't see the angle change; yet keeping 'simple physics demonstration' as the title. It's likely the original video is longer with an explanation but it gets cropped out so you feel stupid. Whalecum to Reddit.


Kiernanstrat

You can see it because the string and match heads don't meet up. The base of the last match is perfectly inline with the string and the top isn't.


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SourNipples_

What a narcissist lmao


UncleShaggy69

This makes me feel better about not getting my masters in mechanical engineering


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Ajedi32

That's not it. If you were to push the bottle slightly under the table with your finger instead of placing the third match you could move the center of gravity even further, but that wouldn't stop it from falling. The first matchstick would just tip over the ledge and the entire thing would fall. The key here is that after the third matchstick is placed the first matchstick isn't merely balancing on the ledge anymore, it's supported by the second and third matchsticks. It *can't* tip over without pushing the second matchstick out of position. The three matchsticks basically form a hook. Depending on how much friction there is between the second matchstick and the string, it could theoretically support the entire weight of the bottle on nothing but the tip of the first matchstick. (Though realistically there probably isn't _that_ much friction holding the second matchstick in place, which is why they didn't actually do that here.) I'm a little baffled the parent comment here managed to get almost 200 upvotes without anyone else pointing this out. Makes you wonder how many things on Reddit are upvoted merely because they _sound_ right rather than because the people supporting them actually thought it through.


doodlebug001

Thank you, I was breaking my brain trying to understand how that comment was correct. Your explanation was what I intuited in the first place.


TheTigersAreNotReal

If you want to get really technical, this is a typical [cantilever beam](https://en.m.wikipedia.org/wiki/Cantilever) problem you would get in an engineering course. The third matchstick is applying an upward force on the end of the first matchstick. This creates a [“moment”](https://web.mit.edu/4.441/1_lectures/1_lecture5/1_lecture5.html) on the first matchstick, with the fulcrum being the position of the string. The rotational effect of the moment forces the long side of the first matchstick downward into the table, preventing it from tipping over.


phpdevster

> I'm a little baffled the parent comment here managed to get almost 200 upvotes without anyone else pointing this out. Makes you wonder how many things on Reddit are upvoted merely because they sound right rather than because the people supporting them actually thought it through. I'm willing to be a *lot*. Now and again people post interesting space images in /r/space and /r/astronomy and there's always a lot of incorrect information that gets passed around. It's interesting to see shit like that in topics you have deep knowledge about. Your reply the parent comment is correct. At the end of the day, the match sticks are made to form a hook. *How* they form a hook is mildly interesting, but easy to work out when you draw out the forces involved. But how a hook works here isn't interesting. We've all seen how one behaves. If you substituted those match sticks with a solid metal hook (even one in the exact same shape), nobody would bat an eye.


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EternalPhi

Especially considering *you can see the tip of the 3rd matchstick touching the tip of the first matchstick*, which would obviously be angled *away* from the table.


oijsef

Read the top comment and thought I was so dumb for thinking the string angles were offsetting something. Still too dumb to get as far as your explanation though so thank you! I wonder if this is some point you can take advantage of, like instead of friction use screws and then you don't need as much anchor?


inko75

yeah there's some dumb shit up above. there's also like 500 examples of this posted already and humans actually use some of these principles when climbing/hanging onto ledges.


Croatia2Montenegro

As someone who knows something about something, and have read Reddit comments about that something that sound like they know what they are talking about but actually know nothing close. You’re spot on. I do think, in general Reddit is on of the smarter guys in the room, but their arrogance keeps them from ever getting close to the smartest guy in the room. That guy is just a lurker who doesn’t engage with this BS.


McGuirk808

I don't think center of gravity is part of the deal here. I think the center matchstick is sort of making a hook out of the top matchstick. By supporting the red head of the top match in front of the pivot ooint created by the string, it prevents the top match from flipping forwards under the weight and essentially has made it a stable hook.


1ampoc

That's part of the answer, but it is also necessary for the COM to be right below the edge. If u take the bottle with all the matches as your system, u will realise that ur explanation only involves internal forces and thus only proves the rigidity of the matchstick structure. There are only 2 external forces acting on the system - gravity at the COM and the normal contact force at the table. Friction is possible, but in equilibrium it would be 0 since it serves as the only horizontal force. Without COM being right under the edge, there would be a torque about the COM. However, the reason COM is below the edge may not be because the third matchstick is tilted inwards. It could simply be because the system is rigid, and so after rotating, it would enter a stable equilibrium where COM is below the edge. In fact, any rigid L-shape object which can be positioned such that the COM is right below the edge would probably achieve stable equilibrium (Try it)


Skuuder

This is incorrect.


hardonchairs

Yeah looks like the last match is just preventing the first match from pivoting right at the edge. Since it can't pivot, it hangs on like a hook.


cock_daniels

looks like the angled match causes extra load points on the edge of the bench which neutralize the moment of force on what appears to be the weight-bearing match.


[deleted]

r/confidentlyincorrect


ThatBee9614

Not at all but good try


[deleted]

Really don't think that's right, the "trick" is that the single match separating the rope is a floor supported by the force of the ropes clenching it together, then the 3rd match/middle match connecting the two is taking all the force from the 1st match and as the 1st match tries to tip over under the weight of the whole thing it's pushing the 3rd match down into the 2nd which now has to move the match down further in order to tip now, and because the force of the rope clenching is greater than the gravitational force it doesn't move


Aeolian_Leaf

It's not though, you can clearly see the two match heads are together.


[deleted]

Bracing the matches the way they have turns the structure into a rigid object. That's all, that's the trick. An L-shaped piece of wood wouldn't fall off; this won't fall for the same reason.


Martin_Samuelson

Yup. And it’s the tension of the band that is squeezing the three sticks together.


Cepitore

The “trick” is that in order for the bottle to fall, the first match needs to tip head first, but it’s being braced by the other two matches and is unable to tip.


norsurfit

I was waiting for the matches to light themselves on fire!


After-Cell

That distraction could be part of it...


[deleted]

Totally missed the Gorilla Glue application


A-Hot-Ceeto

We need a physics update


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Proudpapa7

I Can’t hold a candle to your logic.


Way_to_many_pancakes

It’s literally physics it’s not a magic trick


After-Cell

I need an explainer video. The forces pushing from and to... I just don't seem to get it Edit: Ah. I think the last march moves the center of gravity under the bench, because its head is closer to the camera


Meesterchongo

The last match uses the force of the bottle that is pushing down due to gravity to now push it up and equal its balance. That’s due to the horizontal one that is holding the tension of the string. The string look to push that it which instead forces the middle one up into the top one counter balancing. I think I could be wrong and a potato


Way_to_many_pancakes

Look it up but uhhh sure that sounds right I can’t remember how it does it


BenniesBananas

I wish it did light on fire. My imp brain would have just watched in childish amusement. Now I hurt inside and my cortexes are angry. Bye Reddit, we will try again tomorrow.


Oshen11111

Haha me too....I was like oh shit this dudes gunna light all 3 of these bad boys somehow with this string and bottle...fantastic let's watch.


TinanasaurusRex

I thought the video ended early because I was waiting for this.


Oshen11111

Lol right


fakeplasticdaydream

Theoretically, he could light the back end of the support match and it would burn down to a certain point making this even more fuckerier


someguy7710

Same here. Was disappointed


CatApologist

Practicality aside, I assume there's no upper limit to this? If you used steel i beams and thick steel chains, could you hang your mom off of it?


blah23863

Nothing could hold that kind of weight.


WoolyHitToDie

NFT detected Opinion ignored


raphanum

It was free though, so who cares


HOOTRAGEOUS

Everyone does


DirtyDiaperDog7

Hoot hoot


Linkalee64

"What if you’re raped and forced,,,,, to give birth because you live in America,," "Then you shouldn't have gotten raped." Wow, yeah, that guy is an asshole alright.


WoolyHitToDie

Huh?


Linkalee64

The guy you're replying to. I scrolled through his history to confirm if he was a crypto bro or not, and found that reply from him.


WoolyHitToDie

Ohhhhhh, ye that’s pretty cringe


Theoretical_Action

Cringe


i_have_chosen_a_name

User of new Reddit detected


[deleted]

The fabric of spacetime is shitting itself right now.


MercilessParadox

I'm shitting myself right now


Lysol3435

Opening a black hole around her. That explains why you didn’t get any love. Nothing could escape her gravity


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Textbuk

No she doesn't! She just shifts the centre of gravity. Do not ever inaccurately insult my mum again, you uncultured bovine cell line.


[deleted]

Now THAT'S a mama joke


Cleaglor

Holy shit dude, you killed him


Commercial_Bonus9914

I mean, they'd have to be super thick chains


Aduialion

Alas, you are a man with a vision who is limited by the technology of our times


land-o-thomas

In what world is hanging ur mom impractical?


bruhpotato420

There is an upper limit. The matchsticks can snap


CatApologist

Ahh, thanks for the completely rational response to my ridiculous post.


Matt4Prez2K17

This is like that damn floating structure made of chains or strings


meponder

Tensegrity tables?


Matt4Prez2K17

THOSE


Demogorgon02

I made one a couple years back, and I commend the people who invented them


raphanum

Tegridy


[deleted]

Randy Marsh’s next hobby will be woodworking. MMW.


colby_jack_cheese

I can understand the way those tables work as it seems to be about balance but I still don’t understand this video


StunningSprinkles854

The matches are used to offset the vertical loading so that it aligns with the timber saw horse beneath the match. You can see the cord is resting on the timber not the match.


[deleted]

Tegrity Weed


Lickwidghost

Tegrity Farms


WarmTastyLava

Like your [spine](https://youtu.be/JHJNNZ_zTls)


strain_of_thought

Well that finally answers a question I have had my entire damn life about how the hell the spine can structurally support the body when it's so obviously flimsy and delicate.


HairballTheory

Load transfer


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LedParade

Sperm migration


Disposable_Fingers

Semen switch.


Sir_Micks_Alot69

Ejaculate exchange.


[deleted]

Jizz juxtaposition


atthedustin

Nut correspondence


[deleted]

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HighSpeedDoggo

Male testosterone exchange


adhominem_expert

I do it every morning


[deleted]

Only do this if she's on birth control


DaGinja34

This is something you would not want to discover when the witch trials were going on.


joeChump

I don’t think they had Lipton back then.


Lunaris52

They didn’t have witches either


xoxoyoyo

it is called a hook. it doesn't look like a hook but it works exactly the same


TheBlacktom

Yep. It's a ? Instead of an L.


serch_the_stoic

I literally thought it was glue and this comment actually made me understand how this works..... genuine thank you to you


TheBlacktom

The trick is the camera angle. From the side it would be obvious.


psychojunglecat3

Thank you. This was hurting my brain and “hook” made it click.


Johnny90

Woah....


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NuclearHoagie

I'm pretty sure this could still work without any friction at all, you'd just have to align things precisely. Every piece is held in place by a balance of weight, tension, and normal forces, I don't see much friction acting here in the first place.


StoneHolder28

The first match is on a slight angle, so no friction would let it slide right off. I struggled with that when I made a set with smooth surfaces.


mib_sum1ls

your brain is held in place by a balance of weight, tension and normal forces


CallieCallie86

It's not friction, it's the horizontal forces canceling out


The_Reddit_Pigeon

Hmm . . . How


[deleted]

The 3rd matchstick prevents the 1st one from dipping down, so everything hangs like a hook. The 2nd one is supporting the 3rd one because it is pinched in place by the string from the weight of the bottle


comeonsomebody

The weight is exchanged when the glory of the unflamed is crafted


SoxxoxSmox

I think if you're approaching it from the perspective of "how does the center of gravity not hang over the edge of the table," the trick is to note that the bottle is angled slightly towards the table, and the vertical match is angled backwards, causing it to hang underneath the table even further. You can see it more clearly in [this example linked elsewhere in the thread using a hammer.](https://physics.stackexchange.com/questions/307721/hanging-a-hammer-from-a-table-and-a-stick-so-that-its-midpoint-is-outside-of-the). The much heavier head of the hammer moves the structure's center of gravity back under the table surface, while the hammer handle provides torque to prevent the ruler from tipping over the edge.


p1um5mu991er

You mean I'm supposed to pay attention at school?


academicRedditor

Love it


_lablover_

It's impressive how many people decide to correct a partially correct but incomplete explanation and give a different but still incomplete explanation that is therefore equally as wrong


beepbeeboo

BURN THE WITCH!


Mother-Joe

can someone explain examples where this would be used in actuality


tegith

Most architecture and bridges would use similar properties. The diamond shape created by the two matches in the string distributes the force to put as little force into the match on the table as possible. If you really want your mind blown, the vertical match within the diamond shape is a zero force member. Meaning there is no tension or compression within the match at all. It's just kinda vibing there


RollingLord

Don’t think the vertical piece is a zero-force member. It’s at a joint with a reaction force from the match lying on the table. Furthermore, at the “connection” point, the horizontal member doesn’t have a hinge, therefore forces can be transferred from the vertical member to the horizontal member. To clarify, the horizontal member is basically just a simply supported beam with a point load acting on the center.


OneMoreAccount4Porn

Fancy architecture.


southernmamallama

My brain does not compute. Are you a wizard???


soberscotsman80

When your math teachers said that you use math in everyday life this is the kind of things they were referencing


nec240b

Wait, so this is basically like those purse hooks people use at restaurant tables and bar counters? The ones where only a coin-size circle lays on the top surface?


burdman89

They used matches and set nothing on fire? Dislike


[deleted]

So what your telling me is buildings I trust with my life to stay together could quite possibly be held together with tooth picks and some chewing gum.. awesome


thespicypyro

*squints* “Magnets…”


slime445

Hold the fuck up


Blort_McFluffuhgus

Fascinating


AceTheJ

It’s a simple spell but quite unbreakable


Gfuelfiend2020

The trick is that the weight on the match only allowed the glue under the match stick to dry while he played with the string for fun


Wildwood_Hills270

That’s so fast acting super glue /s


daguerre

But when does the fire start?


BeneficialUse8570

*stands on jar*


moumous87

The simple beauty of black magic fuckery


DependentYou7405

Now I don't have to worry about keeping my lemon juice suspended while on the go.


[deleted]

Flat earthers were right! Gravity isn’t real!


topredditbot

Hey /u/overcookedsloth48, This is now the top post on reddit. It will be recorded at /r/topofreddit with all the other top posts.


[deleted]

Now set it on fire


nonlinear_nyc

Make it burn!!!


yourdad300

No wayy


principe_olbaid

Burn the witch!


ExactReport691

Total and complete fuckery


theineffablebob

Idk kinda boring Just turn on BBC news for me


racecarjohnny2825

I don’t remember the movie but the quote was”a physics genius could hang a elephant off a cliff with a shoe string”


myusrnameisthis

I'm sitting here, watching this fucker lift the weight and the stupid fucking matches dont budge. I wait for a beat, and then I start cracking up. "Wtf is this black magic? Shit, I got to post this on blackmagicfuckery." That is when i realized i was watching it here alteady. I also realized my edible had kicked in. This had me stunned for a moment until I worked it out. Lol


New_Cause_5607

Was I the only one waiting for something to catch on fire?


Various_Wash_4577

Those pre-formed rafter assemblies you see stacked together at construction sites when they're delivered. Those are engineered as a truss to push up as weight is pushing down from the roof load. All the angles of those cross braces are put in at specific angles and locations for maximum strength. Thats why its better to purchase them already pre-formed by companies that specialize in rafter trusses. The principle of this video is very similar to a truss making an opposing force beneficial to its strength.


didymus_fng

I’m disappointed there wasn’t fire involved.


Bitter-Heat-8767

So wait, where’s the fire?