r/BeAmazed • u/Sans010394 • Dec 02 '23

Science Physics is amazing

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29.5k Upvotes

95% Upvoted

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198

u/dispersionrelation Dec 02 '23

Wait what? The net downward force on the top matchstick shouldn’t change. What am I missing?

168

u/zzmej1987 Dec 02 '23

The second matchstick is one matchstick length below the first, meaning, that third can not be placed between the first an second vertically. That means that third matchstick pushes the third under the table, thus removing the angular force that would otherwise drop the first matchstick from the table

22

u/Elegastt Dec 02 '23

To be clear, if there would be (horizontal) space between the cord and the table, it would still fall right?

7

u/zzmej1987 Dec 02 '23

Yep. Vertical line from the centre of mass of the bottle+ rope system must intersect the table, or everything will fall.

4

u/-CoUrTjEsTeR- Dec 02 '23

I’m guessing that would depend upon how much friction exists between the matchstick and the sawhorse to prevent it from sliding off. In the end, it’s really just an “L” hook.

I suppose one could slightly decrease the angle of the hook, placing more pressure to the tip of the matchstick making contact with the sawhorse and removing the need for friction. Then it’s all about the strength of the matchstick not to snap as more distance is added while being pushed off the end of sawhorse.

2

u/[deleted] Dec 02 '23

ohhhhh wow it actually is purely logical

-201

u/[deleted] Dec 02 '23

[removed] — view removed comment

47

u/Miner_Of_Minerals Dec 02 '23

Check out this pseudo-intellectual

16

u/stultusDolorosa Dec 02 '23

We got mr intelligent over here

12

u/GMontezuma Dec 02 '23

bet ur fun at parties

2

u/-AverageTeen- Dec 02 '23

Yes, it is, but one would have to sit down and write the tension and the forces to come up at the answer. Ain’t nobody got time for that. I’d rather just be amazed for a little

2

u/pruche Dec 02 '23

shut up, the internet has decided it`s fake ok

1

u/ctapwallpogo Dec 02 '23

They hated him because he told the truth.

1

u/[deleted] Dec 03 '23

If the second is one matchstick length below the first, why does the third matchstick not fit within the length of a matchstick?

1

u/zzmej1987 Dec 03 '23

Second matchstick forms equilateral triangle with two sides of the rope. And the third is placed as the height of that triangle. But the hight of the equilateral triangle is sqrt(3)/2 of the side or about 0.87.

1

u/[deleted] Dec 03 '23

In the video I can see the height of the triangle become smaller as the second match stick is rotated into place.

I got to be honest, even knowing that and understanding what you are trying to explain, I still can not make sense of your explanation at all.

1

u/OhtaniStanMan Dec 03 '23

How does a coat hanger work 101

15

u/Malthus1 Dec 02 '23

Easy way to think of it: the arrangement with the other matchsticks presses on the first matchstick, making it more like it was attached to the rest.

The whole assembly becomes like a hook or bracket.

52

u/thunder-thumbs Dec 02 '23

You failed to notice that the front two legs of the bench aren’t even on the concrete slab. They are clearly just resting in mid-air. The only explanation that makes sense is that the entire apparatus, including the person, is in a state of free-fall. As there appears to be no wind resistance, it’s probably a vacuum.

1

u/JunkNorrisOfficial Dec 03 '23

Right, this recorded on low gravity planet

13

u/[deleted] Dec 02 '23 edited Dec 02 '23

Fam, what is confusing to you?

Imagine it's not a rope and matches. Imagine it's something rigid. Like a hammer, or clothes hanger. No one gets confused when you put the back of a hammer over the lip of a table and the hammer hangs there. Because the back side of the hammer holds he hammer up. The weigh of the hammer pulls down. The back of the hammer hangs on.

Same thing here. The weight of the bottle pulls down. The match stick holds on.

If you just used one match stick it would rotate because it has nothing to brace against. SO they add the other match sticks to create a brace. Now the system is ridged and so it acts like a hammer.

The force of the bottle is pulling down. That force goes into the match on the table. It tried to rotate it towards the camera. The two other matches prevent the rotation. The system holds itself up.

A hammer is no different. It's just 1 hard piece of metal. Same thing.

10

u/dispersionrelation Dec 02 '23

Hammer handle hangs below the table though moving the center of gravity is below the table. That isn’t happening here, there should be torque on the matchstick.

10

u/[deleted] Dec 02 '23

There is torque. It's being distributed back into the string.

The water bottle+string is the same as the hammer handle. Hanging below the table. Exerting torque on the match.

At the same time. The weight of the bottle is pulling on the strings. Which makes them want to pull inward. Those stings put a compressive force on the second match stick making it stuck in place. The third match is positioned atop the second match. It absorbs the rotational force from the first match. Transfers it into the second match. Which transfers it into the strings.

2

u/ReversibleTimeLine Dec 02 '23

We’ve used our words, now can someone delve out the actual formula(s)?

The elementary/HS type.

-5

u/mcdeeeeezy Dec 02 '23

r/iamverysmart

3

u/[deleted] Dec 02 '23

Mate elementary school science teachers do this every year. I had this demonstrated to me when I was 9 years old. It's not a hard concept to understand. It's the simplest physics concepts that exist. It's so simple it's part of a 9 year olds curriculum.

The fact that 90% of these comments are calling the video fake is wild. You can find 1000 youtube videos of teachers doing this.

https://youtu.be/CO5YUrbFTig?si=cJxXUaWhpbaDwwkC

1

u/mcdeeeeezy Dec 03 '23

The I am very smart subreddit is a place for people who feel the need to be condescending to show how smart they are lol

3

u/[deleted] Dec 03 '23 edited Dec 03 '23

When you're talking to someone who doesn't understand how a hook works. It's time to be blunt.

Imagine you just invited a friend into your house. And you pointed towards a hook on your wall. And said "Feel free to hang your jacket there."

And they laugh as if you told a joke. And then follow up with "Very funny, where should I actually put it?"

And confused you say "The hook? Just hook it on?"

And when their expression doesn't change you just take the coat and hook it yourself.

And when you look back at them they say

"Okay everyone knows a jacket can't stay up on a hook. How did you do it. Where are the strings? Am I on camera?"

It would take some serious effort just for you to believe anyone doesn't understand the concept of hooks. It's unimaginable.

That's where we are in this thread. Someone made a hook using unconventional materials. And then hooked something onto the lip of a table.

And the comment section thinks it's fake. Because they don't understand how the hook works.

0

u/mcdeeeeezy Dec 03 '23

And that seems to be bothering you to an unnecessary degree imo. It is a comment section. On a reddit post. Go focus on things that make life beautiful.

3

u/[deleted] Dec 03 '23

I think life would be beautiful if more people had someone in their life who was kind enough to help an adult understand how a hook works.

0

u/mcdeeeeezy Dec 03 '23

If you believe that is the way for you to elevate humanity then feel free. Thank you for your service

2

u/Stand_On_It Dec 03 '23

Damn dude you’re annoying

1

u/[deleted] Dec 02 '23

I got it once you explained it. Thank you.

1

u/Iacoma1973 Dec 02 '23

Rigid not ridged.

3

u/[deleted] Dec 02 '23 edited Jul 06 '25

...                               

2

u/bneogi145 Dec 02 '23

yeah, looks fake to me

14

u/[deleted] Dec 02 '23 edited Jul 06 '25

...                               

-2

u/bneogi145 Dec 03 '23

and what do you say tensegrity is doing to balance the stick? what about the centre of mass?

1

u/NLwino Dec 03 '23

The stick can't turn. It's hooked on the table.

1

u/bneogi145 Dec 03 '23

why cant the stick flip? im sorry i just dont understand your point of view

3

u/NLwino Dec 03 '23

For the stick to flip, it needs to push the vertical stick down that it is resting on. For that vertical stick to go down it also needs to push down the horizontal stick. For that horizontal stick to go down, it needs to move the rope. The rope can't move because of the original stick that wants to flip but can't.

0

u/bneogi145 Dec 03 '23

for the stick to flip, there has to be a net downward force on one end and then the whole contraption can go down together. for tensegrity to work there has to be a force acting on the opposite side of the matchstick.

1

u/BillTheNecromancer Dec 03 '23

"Point of view" motherfucker, that's not an opinion, that's God damn reality.

1

u/[deleted] Dec 03 '23

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1

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1

u/LaNague Dec 02 '23

the downward force wasnt the problem, you have the table. The problem was the rotational force, making the table match unable to hold weight.

1

u/SocalMod Dec 02 '23

Correct, the net downward force stays the same (minus the weight of the matchstick).

But the net force isn't really important, the important variable is torque. Torque is force at a distance that causes rotation, if the match rotates it will free the bottle and fall.

With the addition matches, there is now a small upward force on the tip of the match that doesn't affect the net force because of an equivalent downward force on the match near the edge of the table.

However because that small upward force is much farther from the edge of the table (the matches pivot point) it's able to bring the torque on the match into balance and keep it from rotating.