Slinky Drop Answer
Вставка
- Опубліковано 12 лис 2024
- Want more awesome HD slow-mo? • Does a Falling Slinky ...
Slinky not long enough? Click here: • Supersized Slow-Mo Sli...
How does a slinky fall when extended by its own weight and then released? We discover the surprising answer using a slow motion camera that records 300 frames per second. Answer link: • Slinky Drop Extended
For a great explanation, check out Rhett Allain's analysis here: www.wired.com/w...
vsauce rocks!!!
Always has been!
Yup.
is this the time when Vsauce featured you?
subscribe to you because of vsauce :D
@@blue_birb yea
"And as always, thanks for watching."
*thanks
What?
Thanks
@@Emalo Vsauce's outro
@@zeyy84 ohh yeaa of course now i remember
When 300 fps was fast
130 000 fps. can i run tf2 on my potato pc that fast ?
When less than 1 billion fps was fast
What are you talking about
Derek said it to be ultra-slow motion back then, today some phones can record 480fps & even higher!!
Vsauce?
+Elias linde That's how I got here.
+ERICSPEEd same :P
ME!!!
+Eliaslinde Hello, Michael Here.
Brain Candy
@Soundslikehope We dropped the longest slinky we could find - I think it's pretty impressive. It's linked in the description.
Hello World! Vsauce
hi
So THATS why the Coyote can run on air for a few seconds before he realizes he's run off a cliff and falls.
LMFAOO
@valentine446 your comment is obviously true. But sometimes we anthropomorphise objects to help others relate to the physics.
I have really three important points to explain
. . .
lmfao
Shaibah Wow.
+Untitled Name please explain
I have to explain it, but I didn't say I would
Its like, you have to do your best in your job, but do you do it? nope
It was a joke. He typed 3 points: " . . . " !
It is a suitable alternative but I wouldn't say it is better. Personify has another meaning 'to embody,' which is not what I meant so it is less clear.
It's okay
Actually the answer "end didn't notice" is untheoretical let me explain why the end of spring remained stationary:
When you hold one part of the spring in your hand and allow the second end to elongate as much as it takes to reach equilibrium both the weight force and spring force will be equal (note that the spring force is -k(L2-L1) or (stiffness) x (elongation)), so the only variable for the spring force is elongation.
To have an equal force to its weight it needs to elongate until delta L times K is exactly equal. Now when you drop the upper part it will be pulled by spring force and weight hitting the other end to create a down force and with the impact of both ends the spring force will reach zero and the weight force will be the only force on the system.
To make things simple think of a spring stretched horizontally on a table with hands holding each side and release one side you will not feel any change in forces in the hand holding the spring until the other side hit causing an impact force.
For the ball question, If you attached weight to the end the weight will make an equilibrium by extending the elongation but if the weight is much more than the spring elongation can handle it can't make an equilibrium thus the spring will move downward before getting together.
Thanks bro
@@Mk_114 You're welcome!
Obviously
How scalable is this effect? A 1km slinky?
No gravity then? Its for sure no gravity in action if done on a table.
My intuition would be to say yes. Think of the two ends of the slinky as separate masses. When the top one falls but the bottom one remains stationary, the top one will gain some momentum. When they meet and fuse, that momentum is transferred to the combined mass, which gives it an initial velocity. Then it falls according to gravity and builds up the velocity it would if you just dropped the bottom end.
Great! It's a really nice way to feel it apart from the physics explanation
"Slinky not long enough?"
Don't they sell pills for that?
hi past person
@@rangoony lmao
@@rangoony is he even alive now?
@@clasherworld9821 idfk😂
@@rangoony 😂😂
I literally said "That is AWESOME!" during this video. Thanks for getting me here, Vsauce!
It has been 7 years, so I came here to wake you up
I'm not sure what you're asking but the release dates of the videos may be your answer.
Yes, here it's me scrolling down in the comment section of a video which was uploaded 8 years ago by ya
Am I the only one that saw it clearly in the full speed portion?
no you're not
Yes, you're an unique Snowflake...
Nope. No you're not.
i can see it also very clearly!
No you're not
anthropomorphise - To endow with human qualities; To attribute human characteristics to something that is non-human
(wiktionary)
ascribe human features to something (princeton wordnet)
Thanks, you saved my time
The tennis ball will stay in place (until the wave hits it) because if gravity is pulling it down more because of the weight of the tennis ball, then gravity is also causing the slinky to experience an equal amount of tension. The ball is causing a greater tension force as well as a greater pull of gravity, so the opposite and equal forces cancel out and leave the ball in its place.
or more simply put, the tennis ball becomes part of the original system, and we know what happens in that system.
all golfers tell me to finish with that "flourish" but i could never get them to understand it does nothing - you have already hit the ball. so thank you for proving my point.
The reason golfers finish "with a nice little flourish" is because following through like that is a: good for your arm, and b: helps you know whether you've directed the ball properly; if you don't finish through well, chances are you haven't swung very well either. It has nothing to do with golfers thinking it has some magical effect on the ball. In general it is best to assume that other people aren't doing things for stupid reasons.
That assumption is a good rule of thumb when dealing with experts who have properly studied what they are doing. It breaks down pretty fast when you move away from science and start getting to the areas of religion, the paranormal and conspiracy theories though.
But yeah. When I come across things that legitimate experts are doing that doesn't seem to make sense to me, my first thought is 'what am I not understanding' rather than 'these people are dumb'.
Yeh, his golf analaogy was about as good as his explaination of the slinky.
@@aaronfawcett9911 didn't u like his explanation?
"In general it is best to assume that other people aren't doing things for stupid reasons."
Yet, you are making that exact assumption about a physics expert.
@@salvatronprime9882 This comment's six years old, bud; you could have at least read more than the last line before responding.
something that makes me happy is that this video has 1.5 million views meaning some people are still smart smart enough to entrust the future to
I don't agree with the explanation when it said that the information need to travel all the way to the tennisball to "tell" it to drop. When the slinky just hangs in the air, the gravity pulls it out and gives it a tension that wants it to contract. Due to the gravity that is affecting the whole slinky. When the top part is dropped the tension is released and the slinky is trying to contract to its usual state. And while gravity still affecting the slinky it makes the top part accelerate with a greater speed then "freefall" on that mass should. Due to the tension in the slinky. The same tension that keeps the bottom not to start accelerating before the up tension is low enough to let gravity affect its acceleration. Same goes for the tennisball that makes the slinky extend longer and increases the tension to keep it in a lockes position. I can think of a few experiments that would show this. Greeting //Niklas Björling, Sweden
NIKLAS BJÖRLING yeah except gravity doesn't exist
AARON CAPPELLO: Well yeah you are correct, gravity doesn't really exist but the concept of gravity do, or well it is the easiest way for us to explain the forces that are happening. Though it isn't mass that creates "gravity" as Newton once said, (it works to calculate an approximate but it isn't as correct as Einsteins relativity equations which means it's more correct to use Energy and Momentum to calculate "gravity" which also applies in the same manner on photons and non-mass particles.
maybe in the case of gravity it is a bad example, however it does prove the compression force theory, where if you push a rigid object from one end, it takes time (the time it takes to move at the speed of sound) to move the object at the other end. i think that is what the video is trying to prove and my friends have found it a pretty troubling concept up until i showed them this video in combination with the vsauce one.
But I don t fully understand this. When you think about the middle part of the slinky, you have to consider two tension forces. One pulling up and the other pulling down.they would counteract each other so there's no movement. But what I cant understand is, why doesn't the middle part of the slinky start falling down? Can someone help answer this? I'm sure the answer may be quite obvious but I can't seem to grasp it fully.
Compression wave = information. It's not anthropomorphism to say that the information is "telling" the bottom to fall. In physics this is considered a form of information.
Guy: 300 frames per second,
Veritasium: well that is ULTRA SLO-MO
SLO-MO guys: we got this 1 million fps camera
I watched it at 300 fucks per second.
+Amox Thats a lot of fucks to give for something like this.
IM DIENG xD
+Wrong Code Hi Dieng, I'm Patrick.
u must be dry by now
Amox um... eh... how many ahem...
I was reading the paper Modeling a falling slinky from R. C. Cross and M. S. Wheatland and this video was quoted, someone i'm already subscribed to, what a small world.
300 fps is ultra slow motion camera?
I love the fact that after 3 and a half years, my phone have 240 fps camera (and other slow motion cameras have a quarter of a million fps) :)
Looking forward to see 1000 fps phone cameras in the future :P
your phone cant have more than 60 fps i mean your camera dont be stupid pls
@@milosraskovic6053 why not lol
It happened, there are Xperias with 960fps now
I did at least three stories in Awesome HD slinky slo-mo
Oh yeah I do remember ☺️
Shoutout would be good 👍🏼
Wait wtf how does your comment have 1 like
300 fuc........frames a second
I heard it too xD
Wow! Your videos constantly get better Derek! I have an idea for a video. Dropping a tennis ball and a ping-pong ball and seeing which bounces higher, THEN dropping the ping-pong ball on-top of the tennis ball and asking people what they would expect to happen and why. Just an idea. Keep up the great work!
yup I know the slo-mo guys. I didn't see the link in the description at first. I've actually made a better vid with a Phantom now: /watch?v=uiyMuHuCFo4
I'm giving you a big Hooah! for the educational value of your comment. You're a gentleman and a scholar.
one smart old man
To better understand, place a bit tighter slinky horizontally on a long table and pull it with both hands. Now release only one hand. Whichever hand you release, the slinky collapses towards the other side, because that is where the pull is.
This situation is very similar, you can assume gravity is one hand and his hand the other. When his hand is released, it has to collapse first, because the tension force is still there until it is fully collapsed. Only then, the gravity acts to make it fall.
I have a question. What would happen if the object dropped were not in a state of tension, for example: a chain. Are the results the same because the "message that the top has been released" not traveled instantly, or does the Slinky's internal tension play a major role?
Good question.
from what I've read in the interwebs. this happens because the slinky is contracting as its falling. so yes tension does play a role
+Mete0r27 The same thing WOULD happen! Only in rigid objects the change happens much much faster. You can think of it like this, instead of it being an actual spring that's holding "the bottom" up, it's the intermolecular forces, but it's still tension, and the information still needs to travel through the material, and that still happens at a finite speed. Fun fact, the fall always happen at the speed of sound in that material. :)
There is a simple way to know that the information transfer can not be instantaneous, and that is that it would break universal speed limit, the speed of sound in vacuum (of course, you have to know or accept the proof for why there is such a limit).
Watch vsause video on "how much does a shadow weigh", they talk about it in there (about 5 minutes in)!
I just tried it with a chain now and no it doesnt fall like a slinky, it all falls at the same time
Pretty cool. You can see it without slow-motion too
Once you know what happens you can see it without slowmo!
because I already predicted this would happen, I could see it straight away! :D
Meisje uit Brabant me 2
The simple way to think of this is that each ring of the slinky is experiencing a force towards the adjacent ring. The ring at the bottom is experiencing a force down-wards due to gravity and an upwards force towards the ring above and are in balance. The top ring is experiencing a downward force due to gravity and a downward force from the ring below and are countered by being held. When released, the bottom ring still experiences both forces until the above ring moves, so the slinky cascades.
The amazing thing is that one could see it with naked eye in real time, actually.
Seeing this in 2021 shows how much slow motion camera technology changed over time. 240p and not even that much of framerate.
Vsauce...
Upvote me because I said this word.
Oof
When they got on with dropping the top of the slinky, notice how the bottom (and the entire length of the slinky below his fingers) had already come to rest at a position where the tension force of the spring equaled the pull of gravity. Now when he lets go of the top of the slinky the only force acting on it is gravity. The bottom part (and the rest of slinky until the collapse reaches it) is still being acted upon by equal forces of tension and gravity up until the falling mass meets each part
try searching " Ramesh Raskar: Imaging at a trillion frames per second "
I know i’m 7 years late, but i know exactly what you’re talking about and i love that video!!
The speed of sound applies to him letting go of the slinky. You see, him holding the slinky applies a force what physicists call the "Normal Force" which sets the total force of the slinky to 0 Newtons when held stationary. When he lets go, only the top of the slinky experiences the change immediately, and the change is propagated to the remainder of the slinky through molecular rubberbanding at the speed of sound through a solid (faster than in air).
I could see clearly that without a slow-mo camera.
me too
They were at a bad angle
I agree, partially. The bottom part of the "slinky" is the lightest part of the slinky, and is supporting almost nothing, and the total tension of the slinky is similar to the gravity being acted upon it or in equilibrium, meaning that when it is released the "elastic force" of the slinky is almost the same as gravity and the bottom of the slinky is being pulled up just as much as it is down. Where as the top is pulled down with both gravity and elastic force.
Minute Physics sent me to Veritasium, who sent me to Vsauce! I love them all!
This guy is actually right. The bottom end moves towards the centre and at the same time, gravity pulls it down. Therefore, there is zero displacement of the bottom end. But the upper end is pulled by two forces at once. Which explains the video.
I would love to see this on a larger scale like a person hanging from a bungy rope like a foot from the floor and have it be dropped from a helicopter
The bungee cord would probably snap back and hit the guy in the nuts.
Guitarbage XDDDD you made my day
it remains stationary due to tension. The speed of sound in the slinky is at least 2000 m/s, which would only be visible at 300 fps in 2 frames if the slinky was long enough for the wave to propagate at least the duration of 1 frame, which at 300 fps, is 1/300 = 0.00333... seconds * 2000 m/s = 6-7 meters. FOR TWO FRAMES. What you are seeing is change in momentum, not change in force (aka IMPULSE)
SCIENCE.
Science amazes me every day!
*****
No doubt about it.
No , Jesus invented that
Shhhhhhhhhhhhh mate
that could have been explained abit better, for those confused by his description the body of the slinking isn't falling because the top is pulling on it, and until the top reaches the bottom it's still being pulled by the top due to tension. his description made it sound like it has sentience, so a little confusing to me why he chose such a comparison, none the less never knew a slinky did that before, cool vid!
he explained it wrong. the bottom of the slinky doesn't start moving until the top of the slinky hits it because the upper portion of the slinky is still pulling it up.
I'm gonna trust "some guy" over a physicist...
"The upper portion of the slinky is still pulling it up" is the tension he is talking about in the video. So he explained it exactly how you explained it.
Did you really miss the part where he described tension acting as a force pulling it up?
.....did you miss the part where they talk about tension?
The physicist explained it wrong, but you didn't say why. The part when he said that the bottom of the slinky doesn't know when to fall until it's top reaches the bottom is false because all of the slinky is falling, it's just the tension of the top of the slinky accelerates the bottom of the slinky at the same rate as gravity, so the bottom of the slinky looks like it's just sitting there when it's actually accelerating upwards at 1g (that's zero net force by the way) before the two ends of the slinky even meet, until the top slinky reaches the bottom, then the tension stops, and the whole thing hits the ground. Don't just take my word for it, go search up about "net force" and you will see what I'm talking about.
as long as it is a good slinky the base will stay still until the slinky colapses all the way. This happens because the slinky is trying to contract against gravity (the base is trying to go up to meet the top) but the force of the contraction is equal to the force gravity exerts on it in the opposite direction. The forces cancel eachother out and the base stays still
This works like gravity i think. I heard that if sun disappeared we wouldnt notice that for 8 minutes after it happened. So gravitation works sort of like slinky but much much faster. :) Isnt it?
It works for all kinds of information
If the sun disappeared we wouldn't notice it for 8 minutes because of the speed of light. Light from the sun travels at 3x10^8 m/s and takes approximately 8 minutes to reach Earth.
Steven Horng i know that. But gravity has the same speed so after those 8 minutes we would lose what was holding us to the sun and fly away.
Premislao89 Gravity does not behave in the way you claim. Far from it. Carlip's paper "Abberation and the Speed of Gravity" tells us, in short, that if the sun were to hypothetically disappear we would fly off at a tangent immediately rather than 8 minutes later.
Hashim Khan This way gravity would be faster than light and i heard that nothing can be faster than light. :| Also if gravity doesnt work like that why bottom of spring doesnt fall together with top? If it was immediate bottom wouldnt wait for top to come and hit it.
I love the slinky! I have a silver ones just like this and I never knew it did that. I might have to add that to my contest video. Slinky is putting on a contest. Just go to "slinky contest" and rules and directions are explained for you. I'm having so much fun singing along to their theme song.
I love reading comments from people who don't understand physics yet still watch these kinds of videos, they try and seem clever and just facepalm :)
Or maybe you could just respect that people are trying to learn. No, they don't know it all, and neither do you.
Physics too mainstream
+LiableOne5 Yes, all we need is love.
let him think he's special
Hey Derek! I have another argument ( a much easier one )!
Say, the bottom end of the slinky starts falling as soon as we let go... The whole slinky would be falling. As a result, more kinetic energy would be generated in this case than the actual one ( where it waits till the top end falls ). Since the total work done due to the gravitational force is the same, it means that the loss in ( spring ) potential energy is less in this case. However, this contradicts the fact that every system tends to the configuration of lowest potential energy!!
I didn't need a slowmo cam to see that
Gravity and the slinky are at an equilibrium where gravity is maxed out compared to the recoil tension of the slinky. So when he lets go the bottom can’t go up because gravity already is maxed out pulling it down, the bottom can’t go down because the tension of the recoil in the slinky is holding it up. So only the top, which no longer has the anchor fighting gravity, can fall.
0:20
Well, that's ultra slow-mo.
Another explanation is that the center of mass is in free fall and is displacing downwards as the shape changes and if you understand the calculus, you'll appreciate that while the slinky pulse is at a constant speed, the CM is accelerating at 9.8m/s^2
Really amazing I was amazed that bottom part was stationary i now have understood the Bottom part was stationary due to THE NET FORCe was zero as tension and gravity cancel each other. :D pretty Good , I dont understand why *3 people dislike it ..
Correct, but not only that but the same tension force is also pulling downwards on the top part which combined with gravity also acting downwards produces a downwards acceleration on the top greater than free fall. This is why the top end falls faster than you would expect for much of the descent.
@@arnesaknussemm2427 ah interesting
@@HarshvardhanMishraPIER8 lol it's funny how it's been 7 years and you're still talking about it!
The weight of the falling bottom part is compensated by the pull of the top part until compression force is completely exhausted.
Therefore the top part is falling faster than it normally would at the cost of the floating bottom for a few misdirecting seconds.
The fact that it takes professors to explain and demonstrate this is shocking.
If this guy wants to apply these concepts to sports, he'd better learn about the sports themselves and some basic biomechanics as well as the physics. The "flourish at the end" he mentions tennis and golf players doing is known as a follow through, and is done to decelerate the arm more gradually, reducing the chance of repetitive strain injuries like tennis elbow. The athletes concerned know perfectly well when the ball has left their racquet/club for many, many reasons.
You missed what he said.
What he said was, when you strike a ball, the vibration from the impact takes time to reach your hands so that you can feel it, and by the time you actually feel the vibration from the impact, the ball has traveled a significant distance from the tool you struck the ball with.
***** I understood what he said perfectly well, thank you. He said that you often see golf players doing a "flourish" at the end "thinking (laughing mockingly) that it has some effect on the ball". THAT is where he's totally out of his depth, and should probably keep his mouth shut. He's trying to sound intelligent by mocking the players for thinking their flourish matters to the ball's trajectory, but in the end only demonstrates his own ignorance as to what the follow through's function is.
Sound is the reason it remains stationary. However sound, like light, moves at different speeds through different mediums and circumstances. While in a straight line you're not likely to see it, however there are turns and conflicting contact points slowing it down to a point visible in 300 fps.
Reply if vsauce brought you here!
yep.
e
I also found out about this channel from Vsauce, but it was quite a while ago. Maybe even a year. I've been loving it ever since :)
What if they are wrong? Mabey the slinkey is actualy compressing from both ends but the bottom is comeing up just as fast as gravity is pulling it down, creating an illusion were the bottom isnt moveing.
Derek Schumacher nope they aren't ten years old and can spell maybe
peterisbetterthanyou Yang stfu at least he's coming up with a theory, and thats one more that you made thus far
Chris Vo
+Derek Schumacher Isn't that basically what they said?
yeah, im pretty sure thats what they said but they explained it in terms of forces acting on the bottom of the slinky e.g. the tension (or compression as you put it) is acting upwards and the weight is acting downwards.
In this case there is a force in the spring trying to join the two ends. In this case the underside of the spring tends to rise and the top part to descend. This one descends while the one from above, as a result stands still. If this spring is placed horizontally the two ends would walk at the same speed. The fall velocity of this spring in this case is greater than that of light.
I wish he was my grandpa, you could sit and listen to his stories for hours
Centre of mass of the slinky is below the middle of its length where the acceleration at any point of time can be calculated by
(F-T)/m ;where F is the gravitational force at the centre of mass , T is the tension at the centre of mass , and m as the mass of the slinky.
As the slinky is dropped from its top end the Tension "T" slowly decreases and the acceleration slowly increases reaching its max. Value as g (approx 9.81m/s^2).
This might be the explination of the fall.
In my humble opinion this phenomenon occurs because the top of the slinky is under two downward forces: gravity and the elastic force (which at the atomic level is roughly the result sum of the strong force and electromagnetic force), but at the bottom of the slinky the atoms only are under the gravitational force the elastic force is actually also pulling (not hard enough) in the same direction but the opposite way, so... it's kind of obvious that the top can only go one way and of course, that's down....🤓
I dont know if you guys have seen the Vsauce video on this, called something like how much does a shadow weigh, but he explains why the bottom doesnt move. Its something to do with when you push something, the information is transfered via compression waves. So the bottom doesn't move because it hasn't received the information to move yet.
In the experiment proposed in the end of the video, the same thing will happen that in the first one, but faster. The lower end will have a bigger weight force and so a bigger tension, so when the information that the tension has seized gets there, the acceleration will be bigger. The information will also travel faster due to the weight.
1:01 I think a completely off topic conclusion of this experiment is a demonstration of how the speed at which a brain processes sensory information decays with age :)
Yes! The top falls faster because the forces on it are the force of gravity -mg (as all the slinky has on it) and -T (the force the parts of the slinky have on each other). Therefore a=(-mg-T)m or a=-g -T/m, a more negative acceleration than just g. This also makes sense because the sum of the forces on the bottom must be 0, so for the bottom a=0=-mg+T so T=mg. It gets a little complicated because we're not dealing with halves, but you get the idea.
The funny thing however, is in golf, like most human behavior, that flourish and follow through has an immense amount of impact on your game, some people think your follow through is the most important part, the ball is gone but moving through that precise motion consistently is the challenge so having a good clean follow through keeps it all flowing right through the hard part right past it by the time you feel it, that way you don’t have any brain involved, it’s just the same movement, nice clean line straight through and past the problem area and away goes the ball, but you mess up that follow through and it throws the shot off wildly.
Yes, the flexibility of the pole would have some effect on the velocity of the reaction, but to travel faster than the speed of light, you would have to find a material that has a speed of sound faster than the speed of light. For example, to travel faster than the speed of sound in AIR, then you use a jet, which metal has a speed of sound faster than the speed of sound in air. It moves faster. Check out Super-sized Slow-Mo Slinky Drop and skip forward to 2:33 for exactly what I mean.
it's perfect logic... causality... when you drop the top, it takes a finite time for the information to get to the bottom... it happens in everything.. even solid items when you drop... but obviously it happens much faster to solid ones
I understand this now, basically what is happening is that each curve of the slinky is being held by the curve above it, until the curve above it is no longer held by the curve above it, which is all set in motion by the first curve of the slinky being released by his hand.
It's crazy how 12 years ago, 300 FPS was thought to be ultra slow-mo. Pretty cool how tech has advanced!
There's another way of thinking about this. When an object is dropped, the centre of the mass of the object accelerates towards the ground at g. When you look at the slinky when its been held like at 0:24, its centre of mass will be lower than half way down the slinky, as the slinky is more bunched up at the bottom. The centre of mass accelerates downwards when it's let go, even though not all of the slinky accelerates down. The tope of the slinky actually accelerates faster than g.
It's just science. The tension on the slinky is pulling the bottom 'up' at roughly the same force as gravity, Making the bottom seem to 'float'
I think you might be misunderstanding the concept on display here. "Information" is just shorthand for the more complicated series of interactions that occur as part of any given event. You could make it hover longer by using a longer slinky or dropping it in an environment with lower gravity (Though the gravity would need to be at least strong enough to counter the force of tension in the slinky). But there's no magical way to just slow down the information transfer.
Gravity cannot overpower the remaining tension until the top portion of the slinky rejoins with the rest of itself.
the tension within the slinky is greater than the pull of gravity, party due to the weight of the slinky being more evenly distributed while it is extended.
when it does rejoin, not only is the tension being released, but the weight of the slinky collides with itself, causing outward distribution of tension enabling gravity to finally pull strongly enough on the slinky to move it
Slinky behaves as a closed system, as a whole. Its center of mass will have a uniform "1g" acceleration towards the ground at all times. The system itself is a different story. it is a self/gravity-loaded system in equilibrium, with a potential for dampened oscillation, to boot. So, the bottom will start falling but not before the deformation wave from the system equalization process reaches in (speed of sound in solids, I think) plus all the non-symetrical, in-system, oscillation-augmented elastic deformation into a relaxed spring state.
The centre of mass is a position defined relative to an object or system of objects. It is the average position of all the parts of the system, weighted according to their masses. For simple rigid objects with uniform density, the centre of mass is located at the centroid.
Think about it this way, imagine the slinky force ie the compression strength of the slinky. it will pull itself into the middle of the slinky equally, until we account for gravity pulling down, the top is being pushed down by 2 forces you see, while the bottom is being pulled up (compression to center) and pushed down (gravity). the compression force is at least equal enough to cancel out the force of gravity pulling it down, until the compression energy and the slinky is fully compressed.
Okay, now this is just madness getting these 8 and 10 year old videos recommended for me lol. He’s racking up crazy views without even making more videos.
Do 2 tests side-by-side
1. drop a slinky with a tiny weight at the bottom
2. drop a slinky with a considerably higher weight at the bottom
measure
1. extension (distance from the topmost round to the bottommost one)
2. the time it takes to contract
My guess is that the heavier objects you have at the bottom, the higher the velocity the top will experience.
The bottom round is falling because of gravity, but the tension with the 2nd round keeps it up. The 2nd round is both falling and being pulled down by the 1st one, but the tension with the 3rd round keeps it in place. This propagates to the very top round with increasing tension at every round, causing the topmost round to be pulled down by both, tension and gravity. And until the 1st round's tension with the 2nd one does not decrease, it remains hanging. Like a ceiling lamp hanging at the ceiling until the ceiling falls down reducing tension in the thread/wire between the lamp bulb and the hook in the ceiling
look at it backwards if u hold the top of a splinky gravity pulls the rest of it down but it does not touch the ground because the strength in your arm is greater then gravity and it doesnt go back up becuase gravity is strong enough to hold pretty close to the ground so when u let go of your force the slinky retracts but is held in place by gravitys hand, its like if u held it and gravity decided to let go, the part ur holding wouldnt move well the rest caught up then u would feel the force
the 'center' of the slinky is pulling the top and bottom toward it while falling. Keeping the bottom 'up' and pulling the top down juat a tad faster. Then when it reaches center the whole thing falls.
I prefer that the slinky is under going two motions: first, it is collapsing in on itself, making both ends contract. At the same time, it is also falling as one system due to its center of mass. The top is being pulled more while the pulling forces at the bottom are cancelled out. So it stands still until there is no pulling up due to tension. Pretty much the same as the video explanation but I think a bit clearer.
happiest interviewer ever
was wondering if anyone came here from the slow mo guys, i know i certainly did and subbed loving the videos, well done!
Yes. It's pretty sweet. It has to do with the energy wave going through the slinky as it falls. The longer the slinky, the longer it takes the wave to get to the bottom. Until then, the end of the slink doesn't "know" that it's floating.
Hi. I can answer your question :) The song is "Pendulum" and is available as an apple loop in either iMovie or Garageband on a mac.
Congrats on getting onto reddit, things are only gonna go up from here!
This is a much more accurate explanation than that garbage about information taking time to travel through the slinky or that it takes time for the slinky to "know" what's happened.
Because of tension that was there before he let it go. The fact that the tension was released when he let go traveled with the falling top is why it stood there.
In short, it didn't know it was let go, it still thought that it was being held up.
It's called personification, a literary concept; many of my professors have used it for explaining even far more abstract concepts.