Chaotic 1,2 pendulum

[TacoDude314]

Run, Forrest, Run!!!!!!!!!!!

[TaterGumfries]

22 people don't like chaos.

[DogBoots77]

Best riverdancer ever

[iloverikku714]

i think it want to kick me

[magicalhats15]

I feel like this just doesn't have the understated elegance of a normal pendulum.

[JayKingsley17]

reminds me of a little guy running for his life

[TheMeansardine]

F=MA!!

[TheBserk]

the way it violently swings pisses me off for some reason.

[kai001]

What's the difference between this and a perpetual motion machine?

Also, what's causing the bars to move? Are there magnets in the stand and on the ends of the bars repelling eachother? If not, couldn't that keep it in motion non-stop?

[Dawid4Real]

lols if you paint legs and stuff it woulda almost look like spongebob with crazy legs o_o

[madbillt66]

I used to have a strange nightmare of a thing like this chasing me along the A13......

It can't get out can it? :)

Cheers, Bill

[peterbufano]

beatifull!

[megaverse]

Man this looks unreal ...it really looks like Comps graphic images (CGI) but well i've never played with one so i don't know ;)

[jstarret]

No, this is the natural speed.

[obbytoo]

Now imagine the pendulums were replaced with springs!

[IpkisStanley]

imagine they were replaced with knives. That would be a fun toy!

[Asdam12]

Boy that is lookin' pretty chaotic! But I'm not sure the definition really applies in the right way...

[jstarret]

If there was no friction at all, then it would be truly chaotic.

[Asdam12]

Ah, I see.

[sidewaysfcs0718]

there would still be gravity to slow it down ..since it pulls it downwards ..truely chaotic u would need 0 gravity .. i think..

[Acrimonius1408]

Would I be correct in assuming that this is 'only' an assembly of steel bars on a frame?

'Cos I want to build one.

[jstarret]

They are aluminum bars, but steel would work. It would be more difficult to machine, though. I used cheap ball bearings, unlubricated so that there is little friction. But you are correct, it is as simple as it appears.

[ezekieloak]

This displays non-linear, predictable behaviour. Not chaotic.

[jstarret]

What is your definition of "chaotic"?

[ezekieloak]

Democratic Process.

[allismind]

@ezekieloak actually this IS a chaotic pendulum... it's time evolution varies greatly with only a small change in initial conditions... hence chaotic...which is nonlinear... such as the 3 (or more) body problem in physics

[pgroot26]

@ezekieloak

I'm pretty sure this does display what is defined as "chaotic behavior". I found the equation to predict the motion of one of these for a class I took. The definition of chaotic doesn't mean that it can't be predicted, but that it is extremely sensitive to -and can produced vastly different results due to- specific initial conditions.

[sacr3]

@pgroot26 The only real equation that predicts what happens was created by a program. An Evolutionary Program that went over the many equations humans made and came out with one that was correct

[haakondahl]

@ezekieloak I don't feel that it;s predictable, except in a gross sense, e.g., we know it won't leap to the ceiling.  Within reasonable parameters though, predictable is not an adjective that leaps to mind. I lack the math (been years), but I think I have the concept.

[kyufan1]

@ezekieloak our prof showed us this model to illustrate chaotic motion...

[uNf0rGiViNg]

lol nerds. it just looks trippy

[Hillary092]

haha! agreed.

[picbuck]

I'm sure this is a really, really stupid question from a non-engineer. But...leaving chaos aside as another question, the pendulums seem to remain in motion for an awfully long time.

The energy input was your setting the pendulums into motion with gravitational acceleration, 32 feet per second per second, as I recall.

But they go, and they go, and they go. You sure you're not getting more energy out than you put in?

[jstarret]

No, the energy dissipates and circulates just as it should. Because the bars are pretty massive, it holds a lot of potential energy when you lift it up.

[picbuck]

Oh! The mass of the bars. Right. Dah. Thanks.

[inglishspeeker]

it keeps going for a long time also because there is little friction. those must be nice bearings.

[HereToCorrectYou]

It's Riverdance for nerds..... Love it!

[jstarret]

I agree that chaotic systems are predictable to a certain degree. When you simulate a system like this, though, with no friction, after a while there are events where the pendulum can go over the top in one way or the other with only the tiniest difference in velocity. If the round off error in the simulation says it will go one way while it really will go the other, from then on the simulation is wrong. You can still say what *kind* of things it will do, just not where it will actually be.

[jstarret]

No, it is chaotic. You can write down the equations of motion, but there is no closed form solution, and when you try to compute the orbits numerically, roundoff error soon overwhelms the true dynamics.

[patsagainstrats]

That's retarded, just like its builder.

[jstarret]

Just which comment did I make yesterday that got you so upset? Perhaps you could get dozens of accounts so you could reduce my stars to zero. That would show me.

[callumginty]

Nice video, I liked it.

[LeonSzillard]

yawn

[jstarret]

What did you expect?

[LeonSzillard]

well I simply think it's boring.

I noticed stuff like this when I was a small kid. It's not exactly atomic physics, and "chaotic behaviour" as they call it these days, it's definitely not a new discovery.

[pudah657]

wait is this unpowered? if so AWESOME

[D24D24D]

BORING!!!

[meiun666]

This is actually very interesting, if you know anything at all about it. The starting angle of the two pendulums differing even as little as 0.0000001° leads to immense differences between the paths of the pendulums as the motion continues.

[Lex5151]

Is this a real model or 3D?

[jstarret]

This is a real physical pendulum.

[demonapiccolo]

It would be cute if it were painted like a little man or clown! Then it would just look like it is doing a dance! ^_^

[ChopSockeyJockey]

Am i the only one reminded of John Cleese and the ministry of silly walks ?

[dudu852]

yeah

[claffey]

no ;O)

[thedeadenigma]

it was made like that cause they knew it would do that,...chaotic please

[disndat11]

The damn video doesn't load. Y Y Y Y Y Y???

[jackhannaford]

wiierrd haha

[thedeadenigma]

where's the chaos in that?

[johnnyk2112]

all the principles of chaos took place. you saw strange attractors and infinite yet predictable variety of action.

[badbehaviourTV]

You dumbass

[philgottengains]

And?

[bollockstolife]

That is the freakiest thing ive ever seen on youtube. COOL!

[patriconde]

esto me da miedo

[EBBcrazygood]

You NERDS!!!! u actually think this is cool???!!! it looks like some drunk dancing to a gay song!!! so this happens and that happens and then thi???!!! wat the fuck is wrong with u people????????????? jeez...

[lazymornings]

WOW, FANTASTIC, great job you guys.

[profiley]

i used to date a girl that danced like that.

[28747683]

jajajajjajajajjajajajajjajajaj­ajjaja

[jewfishie2]

@profiley we all know you never dated you dont have to lie

[grimvamp04]

im probably wrong but why the earth is still spinning is because of newtons first law something in motion will stay in motion until acted apon by another force. why something on earth always stops is because of friction or gravity pulling it to a center mass. but in space there is no friction. there is gravity but the earth is so massive its locked in its orbit around the sun. they have been discovering alot about the structer of space and time though so our understanding could change.

[WongTzeYeung]

lol cool

[Angelcape]

wow, that looks messed up =O

[spleenbuster]

how tall are the support arms?

[SacrificeThePoor]

one million feet

[exxclusif]

is the botom magnetic?

[mkflores]

blah blah blah blah blah blah blah!

[boocifer]

gay

[davidtraveller]

The movements are so fast and jerky in the beginning that I thought it was stop-motion film!

[Walenski]

Do it in a vacuum to take out air dampening. Make sure to wear ear plugs though.

[naxr1234]

wow that pendulum sure can dance :P lol

[bassguitar00]

dang. who knew a video on youtube would cause so many insults.

seriously, chill out Acer. in a single comment you say: "you complete moron"... "you stupid fool".

[Acer8088]

A6YHU... you complete moron.... the earth does not stop spinning, you stupid fool.... only thing that's impossible is you ever being intelligent

[KimKim565]

Wrong.

Idiot.

[trigunner87]

you missed his point because you were to busy thinking of an insult, you should have thought harder in my opinion. anyways he means man made perpetual motion, if we could create that we could make sustainable energy output from nothing. take a look at perpetual motion machines ;)

[toweri]

Acer8088: Wrong. The Earth *will* stop "spinning" (actually, become rotationally locked like the Moon to the Earth now) eventually. The friction caused by tidal forces excerted by the Moon and the Sun are slowing the Earth down all the time. This is a measurable - and measured! - phenomenon.

[hhhdean]

your wrong

[fragmentor7]

hes right

[A6YHUTYFITTUYV7]

The earth doesn't use perpetual motion.

[A6YHUTYFITTUYV7]

It can't last forever, or it would be perpetual motion, which is physically impossible.

[lamamba]

correction. it wouldnt be perpetual motion, because it was started with some sort of effort.

[metobeque]

? so what someone started it? the thing is to keep it going forever. but ther's friction on the axis and with air, so...

[sirnlawson]

Lamamba, perpetual motion isn't motion that's started with no effort, it's motion that continues with no effort.

Motion needs effort, an object moving at constant velocity or at rest will continue to do so until acted upon by an unbalanced force. Unbalanced force = effort.

Due to the laws of thermodynamics, getting any useful work from perpetual motion is impossible anyway...the known perpetual motion machines only work on small scales, and are really inefficient. eg the drinking bird toy.

[girlwithaquill]

The drinking bird toy isn't a perpetual motion machine. It requires the evaporation of water from its nose to work. The evaporation of the water (which has positive entropy) is what drives the condensation of the alcohol within the bird (negative entropy) that causes the center of mass to change and flip the bird. Without the water it won't work because it isn't perpetual motion. The only perpetual motion theoretically allowed and observed is current within a superconductor.

[spleenbuster]

an excellent explanation, until you said that perpetual motion can happen. it cannot.

[sirnlawson]

Thanks, and I'm surprised to see someone who actually knows what they're talking about respond to me.

For the non-physicists out there, entropy is used in this context as a measure of the "randomness" of the molecules. Increased entropy means more random, like changing a liquid to gas, and decreased entropy means less random (more ordered), like changing a gas to liquid.

Now lets see if your explanation clarified the system for me. Read my other comment ;)

[sirnlawson]

Ok girlwithaquill, is this how it works?

The water on the bird's nose absorbs some of the heat from the evaporated alcohol, evaporates, and thereby removes heat from the system. The alcohol (now cooled) condenses, and changes the centre of mass changes and the toy dips it's head again, into a cup of warm water, which evaporates the alcohol, expanding it, changing the centre of mass and raising the head of the bird, from where the whole cycle repeats again.

Right or wrong? Am I even close?

[lamamba]

Ok, Thank you.

[hunterr11111]

magnets

[MoneyLuvrBaby]

so it does this forever?

[x3mx3m]

Nothing lasts forever. If you would invent something that did. You would be richer than Bill himself. But due to the laws of physics, it can not be done.

[jasonguyperson]

i don't think that's what they've claimed

[x3mx3m]

No, I just answerd MoneyluvrBaby's comment. "so it does this forever?"

[jasonguyperson]

oh, sorry man. i can't stand how youtube lays out the comments.

[lukichu]

looks like somthin runnin

[TheMaffinMan]

this was...weird

[Vykrel]

looks like half of a fat kid trying to get out of a small space

[The4thSeraphim]

hahaha youre right

[henrymart22760]

hahahaha

[AntonIceChill]

whahahaha XD

[chexed]

the "viscous damping from air friction" could probably be taken down a notch if the legs or whatever you call them were a tad more streamlined... possibly ending up with similar shape to one of those hammers with a thin neck

[minxado]

woah

[gbgolem]

it's scary to watch, so unsystematic o,o / xD

[MeanMrMustard55]

sweet karate kick action at the beginning

[Cysgu]

That would make a well good little man running toy.

[sticky1305]

magnets are fun

[manutdistrash]

dont get it

[midnightsz]

thats really wierd and cool at the same time xD

[AntonIceChill]

magnets are allways fun

[hugoperezlaroche]

there are no magnets in it. read the description. the weird action is due to the pendulum having to parts.

[bar3247]

Looks like a 1980's break dancer or any Break dancer for that matter... lmao

[soaper4]

is this real? if you sayy yes ill believe you, but it looks kinda like stop motion to me.

[jstarret]

It is real, but shot with an ordinary digital camera. I think the frame rate is lower than that of a normal video camera, so the very fast motions of the pendula seem a little jerky.

[zanderkov]

oh perpetual motion exists does it? how shall we utilise this feat of excellence? hmmmmmmmmmm?

[catchyphrase92]

looks like nunchuks!

[kurtwolfang]

wow when i 1st saw it i thought it was magnets but then i realised that its just crazy :)

[nonlethalbychoice]

thats spasm-tastic!

[cenzo188]

that is amazing.

[DoctorGregbert]

That looks speeded up. :/

[Lucidkevin]

Reminds me of someone dancing, and then running, and then near the end walking

[518schenectady]

so there is magnets in that thing right? could u put some copper around it in some spots see how much energy u could get out of one swing of that and see if its enough energy to restart the thing. there is a lot of motion goin on in that thing put copper everywhere on it lol

[jstarret]

There are no magnets or any other energy inputs. The energy is all potential energy from the original position, and it transforms between potential and kinetic energy.

[sqnshl]

no theres no magnets in that thing...in simple and maybe inaccurate terms energy transfers from one pendulum to another causing spikes in the speed at which they move causing the whole thing to go crazy...and no you cant just put coils around and restart the system..laws of physics prevent perpetual motion

[murphy6915]

It is a shame the laws of physics did not work on my ex-wife. Her mouth never stoped. My lawyer did not get it too stop, just go away.

[catchyphrase92]

I am God, hence I dictate that perpetual motion exists!

[gainniny]

hello that is amasing ,....i wonder does it ever stopped,and what about the restoring force

[jstarret]

Sure, it stops after a while but it has a lot of inertia. There is no restoring force, if by that you mean a force other than gravity.

[gainniny]

so the gravity is the only force which was acting on the body while it was at rest....and how is the period of the motion...because if we have to take the length from the pivoting point ...which length do has to be consider

[MathDemos]

just currious but how do mathematicans prove that a specific differintal equation governs a specific object like the double pendulum?

[jstarret]

Assuming the system is frictionless, we can write down the Lagrangian and find the differential equation for the frictionless case. We can then add friction terms, then refine those by adjusting parameters to the differential equation until the simulation matches the real thing. You can find information on how to compute Lagrangians for mechanical systems on Wikipedia. It is a fascinating subject.

[MathDemos]

I will, thanks

[peeeete]

the head readers found in VCR's are made to very exacting standards and the bearings in those are pretty incredible I think.

I intend to make a simple double pendulum using their low coefficient of friction and high mass properties

[felenex1179]

0:45 it does a little dance *noted*

but it does not make a little love or get down tonight-

P.S. look for army general on spring ;)

[2012THETRUTH]

im only 13.. i dunno why am i watching this lol

[jstarret]

13 is not too young. There are a lot of good science videos on YouTube. If you like it, you should pursue it.

[orange07lightning]

haha violent

[addykazim]

Now thats simply cool.. I mean, simple and cool.. lol.. Great work, am gonna try it out.. but would you help me telling whether it needs any particular dimensions to cut the bars and to space them accordingly..??

[jstarret]

There are no particular requirements, but the heavier the bars, the longer it will swing, and of course the more dangerous it is. Get the slipperiest unsealed ball bearings you can find. Sealed bearings are usually packed with grease and will damp the motion out too fast.

[addykazim]

Thanks a lot, I got few metal pieces from which am gonna try it tomorrow.. Ofcourse i will use more efficient bearings, and I was thinking of trying with more number of bars.. anyways thanks again and I will get back to you once I make the model, I may need your help if in case..

[WarzSchoolchild]

This is the most "ZEN" Chaos pendulum I have seen. Congratulations! You could sell these by the thousand, as "Executive Desktop Toys" ;) GO 4 IT!

[appoNo1]

there shud be sum pendulum music on in the bakground!

[MadGello]

With some Triflon and Frictionless bearings?

now THAT is some clean machine... ::)))

[jstarret]

Hey, Ricardo! I have a new one with three lower pendula, and I will be posting a video of it soon. It is much nicer looking and more chaotic.

[pilnik99]

man where did u get that?

[jstarret]

I made it with aluminum stock and cheap low friction ball bearings.

[pilnik99]

can i know exactly how please {no magnet involved??} how come it run such a long time??? was it dificult to make it?

[jstarret]

It is easy. Just drill some holes, cut some rod, and get the slipperiest unsealed ball bearings you can find. I got these at an army surplus store.

[Icemandm]

woah dude...it's...chaotic...

[helimax]

class