A Visual Riddle (The Epitaph of Stevinus)

[@tom_something]

I didn't have time to watch the whole thing, because halfway through I got really excited about building my own perpetual motion machine. Thanks for the how-to guide!

[@bojunchoi6354]

Tom Haflinger lol

[@diamboy]

lol

[@PrinceSqee]

How did it go

[@brohamletmeusethishandle]

uh oh

[@tom_something]

@@PrinceSqee I can't turn it off!

[@druidmechanics]

This is awesome. I found some beads like those in my friend's bedroom drawer and I don't know why they were there.

[@40watt53]

Nice.

[@MonstyrSlayr]

Nice.

[@cody2756]

Nice.

[@stacy__fakename]

Nice.

[@flat0124]

Nice.

[@EctInc]

Great! The animation is smooth and charming.

[@hunszaszist]

The motion even slows down when it performs work, it's sooo good!

[@bambooindark1]

The chain will explode and probably kill all nearby observers due to chain reaction.

[@dan-gy4vu]

Why are you like this

[@Cijan_]

Pun. Liked it.

[@kodethecoder]

👍

[@raskr8137]

kzbin.info/www/bejne/hZPTlHqEeLpsapY

[@herksku9051]

@@raskr8137 i tought this as either a rickroll or a self promotian, it was neither, it was a legend

[@MCC900]

So by extension, the static block could be any shape, no? So long as the whole chain of beads rests in it and the left and right ends are at the same height, the same argument can be applied to state that the ball chain remains static... right?

[@udiprod]

yes, that's right.

[@NorthWindStudios]

+Lilia Chav Only assuming that the closed loop is still added. If the closed loop is not added, it will fall towards the side that stoops lower down.

[@alextan9375]

that's because that way, the bottom half is not symmetrical, therefore it doesn't exert equal forces.

[@pradeepsahoo7243]

You got it MCC900

[@Woodledude]

Yes, but that assumes the chain is of a uniformly weighted material. It's still entirely possible for the chain to be unbalanced, but it would have to have some finite equilibrium point - As in, there'd have to be someplace it would obviously stop when the lower half of the chain is added.

[@pradeepsahoo7243]

I just want to say that it is in an unstable equilibrium state which is really hard to maintain just like in the case of an inverted pendulum. A slight imbalance will cause the whole system to go one way or the other. The shape of the block doesn't matter as long as the beads on the ends of both sides are aligned perfectly assuming that the shape, size, weight, distance between the beads remain constant.

[@copescale9599]

🤮

[@Jar.Headed]

A: Beads slide to the left B: Beads slide to the right C: Beads will crisscross D: Beads will crisscross E: Beads will cha-cha real smooth

[@netric9084]

Hey, I know you! Test tube games discord! Nice running into you in the wild!

[@nicksteele5613]

7 years ago and still such amazing animation, I love this channel

[@io6741]

Obviously the string would get stuck on the upper corner.

[@HarvoSpoon]

2:04 20kg: you can't defeat me 10kg: i know, *but he can* *steeep slope*

[@galzajc1257]

This argument is great, cause it also shows it for any shape, not just a triangle

[@capbarker]

Hi udiprod, it's me again from your halting theorem videos. I'm pretty sure I understand this one, but isn't it quite important information to point out that the lowest bead on each side at 0:07 are at the same height as each other?

[@udiprod]

Yes, you are right. I didn't point it out since I sometimes employ the "show, don't tell" rule.

[@capbarker]

udiprod ok that's fine :)

[@kodethecoder]

Video: What do you think will happen when we let go of the string? Me: I'll steal it because it's made out of gold

[@thetruth5084]

I understand nothing about the forces being applied here, but just by looking at the scenario it's easy to see that it would balance... I'm not sure how I know this, but I do..

[@gressorialNanites]

Probably because you've seen something like this in real life, your brain remembers what happened and expects it to happen again.

[@InfinityDz]

Got here from Feynman's lecture on physics; thanks for the video

[@ArnavBarbaad]

Ya, same here. Though Feynman's explanations are beautiful, I hard trouble understanding this one from the book.

[@metis9692]

hey! same here!

[@vaishnavsmn]

But wait, how can you compare a frictionless environment (the block) to a real life condition (perpetual motion is impossible)? In fact, in frictionless environments, perpetual motion IS possible. Correct me if I'm wrong, but I believe the paradox lies in the fact that Energy can be harvested, not in the perpetual motion itself. Perpetual motion is motion that continues indefinitely without any external source of energy, by definition. This is due to resisting forces. Here, due to the latter's lack, Perpetual motion is possible. On the other hand, harvesting power, ie, greater than one efficiency, is impossible. (One of the thermodynamic laws, I believe). But this introduces a resisting force. An additional (perhaps implied,) condition, that this is less than the imbalance in the chain's weight is needed.

[@udiprod]

You are right. Note however the definition of a "perpetual motion machine": "A perpetual motion machine is a hypothetical machine that can do work indefinitely without an energy source" (from Wikipedia) This refers to machines that not only move endlessly, but produce power endlessly. Even the slightest imbalance in the chain's weight would allow harvesting power endlessly (given smooth enough a surface), so this qualifies as a perpetual motion machine and therefore impossible. Therefore the balance must be perfect.

[@vaishnavsmn]

udiprod So, to qualify as being a perpetual motion machine, it has to be able to do work. Got ya! Nice video, btw

[@udiprod]

Vaishnav Sreekanth Menon Thanks :)

[@FrancisHatesStairs]

not just that it has to do work, even if the environment was frictionless, the fact that the string gets moving by gravity would mean that, with no friction, it would theoretically speed up faster and faster getting infinitely closer to the speed of light (obviously never reaching).

[@selfishlyintrigued]

Actually even in a frictionless environment perpetual motion is still impossible. Radioactive decay will eventually make things in an unfavorable condition to where the machine no longer can be perpetual, and by definition a perpetual motion machine left alone for an infinite amount of time will continue to run. There's other reasons as well, while quantum mechanics never really plays a roll, given an infinite amount of time even ignoring radioactive decay(Which is quantum mechanics, but let's assume in this model radio active decay does not occur) other factors will begin to destroy the machine, from quantum tunneling through to electron imbalances and perturbations. Hell even in a frictionless environment I know of several dozen reasons it's still impossible. That's just to get to perpetual motion as defined, free energy is a whole other story and even more impossible.

[@robdoghd]

I'm just curious, what do you use to animate these?

[@udiprod]

+Blue Umbrella I'm using Autodesk Maya.

[@ashwinalagiri-rajan1180]

@@udiprod holy shit you're a single guy doing this?

[@snaukball8764]

@@udiprod holy shit you're a single guy doing this?

[@thebigsteaks8752]

@@udiprod holy shit you’re a single guy doing this?

[@konakona_.]

@@udiprod holy shit you’re a single guy doing this?

[@shashishshoda8209]

at 1:32 you said that it's a perpetual motion machine but gravitational energy is constantly acting on it which makes it a non-perpetual machine...sir so can u please explain it

[@udiprod]

Yes, that's right. At 0:55 we start a proof by contradiction, with the initial assumption that the top part of the string is unbalanced. From this we conclude that we can build a perpetual motion machine, but since obviously this is impossible, it proves the initial assumption is wrong. This proves the top part of the string must be balanced.

[@shashishshoda8209]

udiprod thanks for the reply but I still have one doubt ,the unbalanced force here is created by gravity which we can consider as infinite source of energy so what I think is that there should not be any contradiction if the beads on the inclined plane keep on revolving because they are acted upon by an infinite source of energy not finite...please correct me if I am wrong.

[@udiprod]

Gravity is not an infinite source of energy. The law of conservation of energy states that the total amount of energy of an isolated system remains the same. If gravity was an infinite source of energy, then this amount (including the earth) would have been infinite. So we could have generated a few more jouls of energy without violating the law (since infinte+1=infinite). What really happens is that the beads have some finite amount of potential energy due to gravity, say 10 jouls. So at most we can convert them to 10 jouls of kinetic energy, but not more than that. But the beads in the video keep accelerating, so this is contradiction number one. But there's another contradiction: The beads in the video don't lose their potential energy. When one bead moves down another moves up. Overall, the potential energy of the beads remains the same. So the kinetic energy really comes out of no where.

[@shashishshoda8209]

udiprod thank you now I understood

[@bambel4997]

The beads would probably fall towards you because from the extra welding some debris was left on the beads so there's more weight on the side of the beads closest to you so they fall towards you

[@DaminGamerMC]

Him: you could calculate the forces but there is an easier way Also him: *uses robots to find another equal string and attaches it, using imaginary robots and tools, to the other string

[@flamencoprof]

Practically, the beads are strung, and can only rotate on an axis pointing in the same direction as the motion considered. i.e they will not rotate when travelling either left or right in the illustration. Thus, they will most likely drape where any point is at the junction of two beads, barring an extremely imbalanced force which can lift a bead over the point against gravity and friction.

[@Im2Ded]

1:25 *Trololo song starts playing in background*

[@j.redhead]

LOL So, true.

[@dogiz6952]

Electrical companies will go bankrupt.

[@jorisdevries99]

You got me.

[@technoultimategaming2999]

*You mad bro?*

[@DonVigaDeFierro]

5 year old joke is still funny.

[@confusioned2249]

"The lower part is symmetrical and exerts equal forces on both sides." But what if, it doesn't ? **ominous vsauce music starts playing**

[@bevweb]

How do you make the Vsauce theme ominous

[@confusioned2249]

@@bevweb Hey vsauce, michael here Where are your arms ? **vsauce music starts playing**

[@bevweb]

@@confusioned2249 (from the computer) hey Vsauce (from behind you) Michael here (from inside your head) what if you were defenseless

[@confusioned2249]

@@bevweb ok that's more terrifying

[@bevweb]

@@confusioned2249 :)

[@terjeoseberg990]

Wow!! So that’s how you make a perpetual motion machine! I’ve been searching for free energy for so long, and this is so simple!!!

[@nagarajansubramani]

00:58 That save!

[@weterman4320]

I hope I'm not the only one that instantly realized it would stay still, I didn't think of the steepness or number of beads until a second or 2 later, like he said, common sense.

[@organumpenguin]

Just watched this and a few other of your videos, these are awesome, thanks and keep up the good work!

[@isuckatediting6898]

what a great channel to learn new stuff during quarantine

[@forg7864]

I like the way you animate these

[@tangy3003]

if there *were* an imbalance, say a heavier bead on the left side, that bead would reach equilibrium on the bottommost point of the closed loop, correct?

[@olivi3r20]

All the videos of this channel look like it's old from 2000, but in a good way

[@blank8969]

1:38 an energy source is present, gravity? i understand that the net force of gravity pulling the left side down negates the force needed to lift the right side up, but for this unrealistic example, it works?

[@blank8969]

a force!

[@blank8969]

what do you mean? if i were to list off the energies of a bouncing rubber ball, you would find that there is a potential energy that changes in relationship to its velocity and distance from the ground. the reason that the rubber ball would increase in potential energy as it bounces away from the floor would be that a force acts on it, that force being gravity.

[@NStripleseven]

The energy present due to gravity is potential energy, and potential energy can only be converted into another form by moving the entire object towards the body it’s attracted to. Gravity by itself cannot add or remove energy to or from a system.

[@NickHey]

So if.. the prism is a uniform material with the same resistance on all sides, because both ends of the beads are about level with each other to gravity, they are balanced, regardless of angle or weight?

[@Winasaurus]

Yes. The top could be an outline of a human being. As long as the bottom sections are at equal height, it cannot slide because connecting the bottom would create perpetual motion.

[@wontpower]

By the way, AP Physics 1 is finished, and I now love Physics. Should I take Physics 2 (continuation of Physics 1) or Physics C (Calculus based Physics)? I'm looking for second opinions.

[@riccardoorlando2262]

+Will Power Quit physics, and take topology.

[@wontpower]

+Riccardo Orlando There are no topology courses at my high school, unfortunately. Physics is the only math-based science they offer.

[@riccardoorlando2262]

Will Power​ really? Not even one teeny tiny bit of geometry? Sad face... EDIT Hold on, I just realized you said high school... Well, topology is uni material, but consider taking a book or two or just googling "topological space". It really is as close as you get to a zero-culture subject: you need no analysis and no linear algebra to begin it.

[@wontpower]

+Riccardo Orlando That sounds like something I would be interested in, but it will have to wait. Even though mathematical knowledge extends far beyond the classroom, I still don't have a firm grasp of set theory. I may have the time to do it during the summer, though. Thanks for the suggestion.

[@riccardoorlando2262]

Will Power You're welcome! I'd suggest books, but they're in Italian :)

[@wheedler]

People in the comments are talking about it being frictionless, but I can't find that mentioned in the video or description.

[@BryceDixonDev]

You're wrong. The answer is D: It'll fall forward because they're round and it's really frickin hard to balance round things on another round thing.

[@udiprod]

+BtheDestroyer prisms are not round. They have flat faces. The prism shown in the video has a bit roundish edges, but you can see in the very first seconds it has large flat sides.

[@BryceDixonDev]

+udiprod Jokes are really funny things but you have to understand that something is a joke for it to be funny.

[@udiprod]

+BtheDestroyer Ok, I thought it might be a joke, but I wasn't sure. Your comment on the halting problem video was serious so it mislead me. Sorry :)

[@BryceDixonDev]

udiprod Don't worry about it.

[@l8dawn]

Is this true for all chain bodies that start and end with the same gravitational potential energy? e.g. the same height

[@mehboobalam3167]

how can you assume that the two forces downwards are equal but there is a difference in forces on the left and right hand sides?

[@legendgamer204]

The math to calculate the forces pulling on either side of the string is to think of either side of the string string as a vector and project that vector onto the height of the triangle. Since both strings are on the same triangle with the same height, they pull with equal force.

[@hamzaabushwereb3982]

Would every combination of steepnesses result in the same outcome? If yes then what is it about triangles that makes this special property possible?

[@udiprod]

It works with any shape. The important property is that both ends of the string are at the same height. This allows the step in the proof were we attach a symmetric string from below.

[@frankman2]

that last part left me wondering what would happen if you tilt the triangle but still have an attached circular chain! It would still be motionless right? Soooo... what gives?

[@udiprod]

A step in the argument shown in the video says that the lower part of the chain is symmetric and therefore even. If you tilt the triangle this is no longer true. So you'll get that the lower part is uneven, and therefore the upper part is uneven too, and they cancel each other out.

[@PotionsMaster666]

Bro this video is a treat. Thanks for the content. ❤️

[@alansmithee419]

0:07. War. What is it good for?

[@joshuahudson2170]

If friction is negligible, the actual answer depends on the minute position of the uppermost ball. You can't get a useful perpetual motion machine out of it. (A unifrom density string clearly remains motionless.)

[@theletteralpha]

0:57 THAT SMOOTH CATCH THO

[@theuncalledfor]

I was thinking it would remain motionless even if slightly unbalanced, because the beads get caught on the edge.

[@photelegy]

1:15 But only with common sense and no knowledge about the forces one could think that on the left the angle is sharper so it wpuld slide, but only for a bit till the bottom part has also more balls on the left. How wpuld you explain it to this person?

[@Skyblue92u]

Wait, does this work for every triangle?

[@kanekeylewer5704]

I do not believe that perpetual motion machines can exist, because it violates so many laws, however 1:43 does not violate any laws, and the statement of "without any energy source" is most likely invalid. Here's why: gravitational potential energy. The mass (and thus the weight) will be pulled down by gravitational potential energy, which will be converted into kinetic energy. Assuming that conditions were perfect (total vacuum meaning no air resistance or no heat transferred to surrounding area), the gpe would be converted to ke, and the velocity of the beads would increase in a counter-clockwise motion. The energy in the cycle would increase due to the added gpe from each turn, and it would, in a way, perpetually spin, while increasing the energy in the cycle. The fault is that 1. heat will be radiated due to friction and 2. the gravitational potential energy would run out, given enough time (likely infinite), and because energy is equivalent to mass (e=mc^2), the mass would 'disappear' in a way, and would then be in the form of energy (infrared radiation given off and kinetic energy in the beads). That is just another reason why perpetual motion machines can not exist. No matter what, whether it be from mass into energy, or just energy itself, there would always be a source of the movement. That is until you get into the quantum physics area, in which case everything just get ridiculously more complicated.

[@udiprod]

The GPE can be converted to kinetic energy only if the GPE itself is decreasing. If a ball, for example, is falling, then it loses height, and its GPE is decreasing. That's why it gathers speed as it falls. But here when one bead is moving down, another is moving up. The center point of the beads mass is not moving (since they revolve around it). Hence the GPE is constant, and so must the kinetic energy be.

[@kanekeylewer5704]

The GPE is constant, but the speed increases because of the original kinetic energy. Because of the momentum, it swings the beads around, and GPE will continue to pull it down as it is not constant. It will just decrease. This is why I said - I do not believe they exist. They are flawed.

[@minercraftal]

Center of gravity effect to only one point is very sensitive... tried the example of the video before, if it don’t have the return connection on the bottom, it DOES slide off one direction, for the tiny differential will move it, and build up more differential ratio, and make it slide off...

[@minercraftal]

@Michael Darrow I said, if don’t have the return connection on the bottom.

[@technoultimategaming2999]

1:26 wouldn't it stop at the bottom?

[@minsapint8007]

Classy presentation of elegant argument

[@JiancongXie]

How you guys produce this kind of animation, such software like ?

[@udiprod]

I'm using Maya.

[@wontpower]

It falls in the z-axis (pointing out from the screen), since it is in an unstable equilibrium. Thanks for the free gold.

[@riccardoorlando2262]

+Will Power Wait, there's a third dimension??

[@wontpower]

+Riccardo Orlando Oops, I wasn't supposed to say that. An FBI agent is now assigned to our case.

[@UtkarshKumarRaut2_0]

How you make such animations? Software suggestions?

[@udiprod]

I'm using Autodesk Maya. I'm sure there are other options as well, but I only know Maya.

[@UtkarshKumarRaut2_0]

I usually display your informative videos during our Workshops, there people asked me this question. Thanks for such content.

[@udiprod]

Utkarsh Kumar Raut Thanks :) I'm curious, which workshops are these?

[@TheOfficialCzex]

Don't we need to know the angle of the slopes?

[@vovochen]

We miss you !!!

[@pluhmpy6855]

Lets say the one with more beads has weights in the beads. Would that make it possible to be a "PMM"?

[@udiprod]

No. The weights will simply sink down until they reach the bottom and then remain there.

[@Pathsfound]

Solution 1: force vectors. Solution 2: thermodynamics

[@nightraysmoon]

I think this kind of leads into the mould effect for the perpetual motion of the beads.

[@Blue-Maned_Hawk]

What if the geometry of the area is non-euclidean?

[@muhammedafser2352]

Good animation and explanation

[@r34n1m4t3d]

I think all your videos are fantastic; keep it up.

[@y2kparth]

Tell me if I'm wrong -----> Let the longer side of string be L, and the shorter one be l. Mass of longer side --- (ML/L+l) ; Mass of shorter side --- (Ml/L+l). Let A be the angle opposite to the shorter side (Shorter Angle), and B be the angle opposite to the longer side (Bigger Angle). Taking the string as one system ----> Forces on the System : --- (ML/L+l).g.sinA parallel to the side L (Ml/L+l).g.sinB parallel to the side l. If we consider these two forces to be equal ---> (ML/L+l).g.sinA = (Ml/L+l).g.sinB Thus, L.sinA = l.sinB This has to be true (or the sine rule would be wrong).

[@Dartnix]

I love the animations

[@Aranimda]

My thougt: No idea if they are balanced but there still is friction so it probably stays put.

[@VenThusiaist]

I knew it wouldn't fall because I turned them into two right angled Triangles by making a peak-to-base slice in my mind and saw that the slopes of the two Triangles were the same.

[@0hate9]

the easiest solution to a problem: "well, there are three possible outcomes, and only one of them doesn't VIOLATE THE SECOND LAW OF THERMODYNAMICS, so I guess it's that one."

[@guilhermemrdeath]

I read this in the Richard Feynman lecture I had to check.

[@baluza5216]

Great video!

[@andrewsauer2729]

The acceleration due to gravity of an object on a slope, neglecting friction, is gsin(theta) or go/h. Multiplying that by the amount of weight on the adjacent side, we get acceleration=goa/h. Looking at th other side, theta'=90-theta, so sin(theta')=cos(theta). so the acceleration due to gravity is ga/h. Multiplying by the amount of weight on the opposite side, we get acceleration=goa/h again. So the acceleration due to gravity is the same on both sides and therefore the force is the same, it balances out since this device is essentially a pully. Sorry this is worded confusing, but it makes sense to me and my final answer is that it will not move. I will now look up and see if I am right.

[@m4riel]

I may be wrong, but I don't think that's a good argument. You can easily use geometry and vector decomposition to prove it, but you'll also see that it only works if we ignore friction. Since we're ignoring friction, thus energy loss, we can't say perpetual motion is impossible. That's physics book explanation in a nutshell

[@udiprod]

It's not just perpetual motion that happens if the string slides to the left. The loop starts at standstill, and we releast it it starts rotating. Then it continues to accelerate. So it produces energy out of nothing.

[@m4riel]

@@udiprod That's right. The animation somehow made me think it was uniform motion when it has perpetual acceleration. Thanks for responding :)

[@DylanIsSoSpooky]

It’s staying still because in the right it’s steep but the beeds pull on it and on the left it’s not steep which helps it go down that way too so they are both equal…

[@Supuhstar]

There's a galaxy here. He says that, with the closed loop that moves, it's performing useful work without any energy source. In fact, its energy source would be gravity, via the Higgs Field. This is an energy source we humans forget about often, but still take advantage of for endless energy in the form of hydroelectric power generators, so it's not unreasonable to imagine we could take advantage of it elsewhere too

[@dabs4270]

gravity isnt an energy sourse, you can only get energy from it if the object loses gravitational potential energy (goes further down the gravity wheel, where you will need energy to push it back up), therefore you aren't generating energy, only changing it's form in the case of hydroelectric generators, this is eaxctly what is happening, we are only turning gravitational potential energy into electricity, gravity isn't creating any energy that wasn't already there in the example of the closed loop in the video, it's getting kinect energy WITHOUT going lower down, therefore it's getting energy from nothing, which is impossible

[@JimGiant]

I intuitively thought the string would stand still. I couldn't figure out why in the 5 seconds you gave us but realised the answer would be a: More complicated than friction b: The answer should apply to any different slopes with the same height base in a frictionless environment. Clever answer. It's a useful technique trying to rule out answers based on whether they would lead to absurd conclusions.

[@nutbox8000]

I'm just going to assume that this has nothing to do with the quote on stevinus' gravestone?

[@cara-seyun]

Did this only apply to right angles?

[@Winasaurus]

Works with any shape as long as the strings start and end at the same height. Since you can take any shape, and if you can connect the bottom, then for it to slide would mean it "rotates" around the whole shape.

[@highvelocitytictac4232]

My grey matter just doubled

[@Pinkcircleguy]

thank you funny physic man that i am currently watching at 12:38 am

[@batman3698]

So basically, if the chain on top of any shape have each end at the same elevation its always balanced

[@Kram1032]

Awesome! Such a simple explanation :)

[@duranmclemore8392]

it's not perpetual, there's other forces like FRICTION. Plus adding the additional string is introducing more forces to the equation, thus altering the outcome

[@kdbacho]

Not really. On a ramp friction is proportional to the normal force of the object, not its speed. As long as the net force of the strings themselves is greater than the uFn, where u is the static coefficient of friction and Fn is the normal force(which is proportional to the strings mg) then the string could still accelerate. Thus considering friction alone its still possible to have perpetual motion as described in the video(again note that this cannot happen since the forces balance). The only other force that I can think of that could make a difference is drag, but that still allows the machine to do useful work until a certain speed. Then u could just reset it. Either way the argument presented in the video is sound.

[@thanhnguyenuc8545]

amazing animation! what software did you use?

[@udiprod]

Thanks! I'm using Maya

[@NathanRiveraMelo]

Wow, this is awesome.

[@confused6526]

Good thinking! And it is really fun!

[@ultrite2696]

I'm going to do it yo this guy just explained king crimson

[@bevweb]

Thanks KZbin recommendations

[@Krantz_]

This may be my epitaph right now, but in time, confusion will be my epitaph

[@jayrich6532]

you would need a magnet to pull the heavier part of the beads back up into position to start the propelling motion again. otherwise the heavy part of the beads will just hang at the bottom...so simple, add magnets to propell the beads over and over

[@vanilla_cookies0603]

no it will not work like that.

[@konfuse7116]

This is brilliant

[@maljamin]

Uh oh you have probably inspired countless perpetual motion projects now on youtube. I WILL MAKE THE DEVICE HE DARES TO SAY IS IMPOSSIBLE

[@_JUNGSEIPEI_]

Its also because the downward component of both their force vectors are proportional to the height of the triangle.

[@DarkGharren]

Very nicely animated!

[@gerardmartin1376]

I disagree with the "common sense" demonstration: perpetual motion does not exist because of energy loss (by friction for example, or by the small wheel with the light bulb as shown in the video) out of a closed system, not because the chain is necessarily balanced. Interesting video though.

[@udiprod]

Thanks. But like you said, the light bulb demonstrates an energy leak. If the chain is unbalanced it will perpetually rotate, and we can we use it to light a bulb forever.

[@gerardmartin1376]

@@udiprod i have thought of it twice, and my vision is clearer. Thanks for taking time to make a reply. The full logic behind this is too simplified in the video and that's why it made me confused. I still think a few more steps of explanation with another approach would be an improvement. In a way, it forced me to push my neurons into work, which is not bad :-).

[@jojojoji24]

*So the conclusion is if it produces infinite energy, it doesn not exist, which is something that I am looking for, for ages*

[@Voltaic314]

I feel like this statement is too absolute. It could be possible that when you attach the lower end then let go, it doesn't keep moving forever but rather keeps rotating until frictional energy overcomes the kinetic energy causing a meta-stable stop position.

We aren't considering friction here.

[@dogiz6952]

What if there is less friction on one side?

[@dewolenyt]

Guess

[@Drachensingsang]

friction wasnt even taken into consideration. This doesnt even need to be a physical problem, you can solve it mathematically. it's a combination of angle and length that results in equal pull as long as both end-points rest on the same plane.

[@katzen3314]

There is no resultant force due to gravity so there is no movement so friction does not matter, as friction only ever applies a force when there is motion.

[@emmajane5624]

Katzen4u there's static friction though? which occurs when there is a force that would cause movement if it were greater than the static friction

[@sleetskate]

wat happens if i pull on the circular string

[@udiprod]

+sleetskate If there's no friction, it will start rotating at constant speed. Just like if you pull, say, a rotating chair, it will start rotating. Of course IRL there's friction, so it gradually slows down to a halt again.

[@jasonneu81]

+udiprod Even your own explanation in this comment proves the conclusion of perpetual motion (you use it as evidence by contradiction) has to be wrong. Thus the commen sense solution is actually just completely illogical, the only actual solution is doing the maths which would demonstrate your point much better imo.

[@udiprod]

+Jason Neu I'm not sure I understand what you mean. In the video we show that if the upper part pulls left, then there's a constant force rotating the loop. This will cause the loop not only to start rotating, but to gradually accelerate, which will allow us to pull out energy and put it to use. This violates conservation of energy. So if we believe in the law of conservation of energy, then the upper part can't pull neither left nor right.

[@jasonneu81]

udiprod That is completely wrong, the string can move left or right, as you said in your comment even if the string moves (left or right) that won't result in perpetual motion because of friction. The mathematical proof is logical and good to understand, but the "common sense" proof is wrong and illogical. Hope you get the point now.

[@udiprod]

+Jason Neu In a previous comment I said that if there's no friction, and someone pulls the string (exerts force on it), then due to no-friction it will continue rotating. In the video we explore a different scenario: there is possibly some friction, but the upper part of the string exerts force pulling the string to the left, and this force remains constant. If this force was stronger the friction to begin with, then it remains stronger then friction, and a perpetual motion will take place.

[@sPACEmANtYLERSPACE]

"Slide to the left" "Slide to the right" me: "crisscross! Crisscross!"

[@YusefRhymer]

So it seems this would be true for any shape of platform as long as the string spans the length of the platform's base. Since as long as the string spans the length of the platforms base, a second string attached to each end and hung down underneath will always be symmetrical in it's hanging...So if the length of one object spans the lenth of the base of another object which the first object lays flat on, it's(1st object's) weight will always be evenly distributed across the second object...hmm, or maybe the base has to be the widest part of the platform object as well...

[@udiprod]

You are right. It's working for any shape. As long as the second string attached from below is hanging from two points of equal height, it will be symmetrical and the proof will work. You don't need even the base to be of any particular length.

[@YusefRhymer]

ah ok I get that, Thx!