Veritasium - 2021-05-29
Even some physics professors say this craft breaks the laws of physics. This video is sponsored by Kiwico, For 50% off your first month of any subscription crate from KiwiCo (available in 40 countries!) head to https://www.kiwico.com/Veritasium50 ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀ A HUGE thanks to Rick and Neil for letting me drive Blackbird. Check out Rick's YouTube Channel for more in depth videos and explanations on going faster than the wind downwind -- https://ve42.co/Rick Gene Nagata made the shoot possible. If you’re a video nerd like me, check out his channel, Potato Jet: https://www.youtube.com/c/PotatoJet/featured. Xyla Foxlin for made the model cart used in this video. Xyla builds amazing things like rockets and canoes, check it out! https://www.youtube.com/c/xylafoxlin/ ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀ References Jack Goodman's YouTube video -- https://ve42.co/Goodman Rick's treadmill footage -- https://ve42.co/Treadmill Rick's multiple explanations of how Blackbird works -- https://ve42.co/DDWFTTW Forum discussions -- https://ve42.co/forum Blog -- https://ve42.co/blog1 and retraction https://ve42.co/BlogRetraction Gaunaa, M., Øye, S., & Mikkelsen, R. F. (2009). Theory and design of flow driven vehicles using rotors for energy conversion. In EWEC 2009 Proceedings online EWEC Md. Sadak Ali Khan, Syed Ali Sufiyan, Jibu Thomas George, Md. Nizamuddin Ahmed. Analysis of Down-Wind Propeller Vehicle. International Journal of Scientific and Research Publications, 3, 4. (April 2013) ISSN 2250-3153. (www.ijsrp.org) ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀ Special thanks to Patreon supporters: Bill Linder, Paul Peijzel, Crated Comments, Anna, Mac Malkawi, Michael Schneider, Oleksii Leonov, Jim Osmun, Tyson McDowell, Ludovic Robillard, Jim buckmaster, fanime96, Juan Benet, Ruslan Khroma, Robert Blum, Richard Sundvall, Lee Redden, Vincent, Marinus Kuivenhoven, Alfred Wallace, Arjun Chakroborty, Joar Wandborg, Clayton Greenwell, Pindex, Michael Krugman, Cy 'kkm' K'Nelson, Sam Lutfi, Ron Neal ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀ Thanks to James Lincoln for building the initial prototypes for a model blackbird. Written by Derek Muller, James Lincoln, and Petr Lebedev Animation by Mike Radjabov and Iván Tello Filmed by Gene Nagata, Derek Muller, Trenton Oliver, AJ Fillo and Emily Zhang Edited by Trenton Oliver Music from Epidemic Sound https://epidemicsound.com Additional video supplied by Getty Images Produced by AJ Fillo
When your online argument with random people is so heated you ended up building a vehicle that seems to defy logic....
@TrueHelpTV we have a winner
seem's like is werry important.. where is terain slope measuring?, where is GPS surface data?? well.. there we go.. there can exist some equilibrium.. for demonstration.. yaa even ponzi found.. even cold fusion is prover 4x from 11try.. well we still burn coal and oil... thats like 50 year ago.. i am dissapointed..
FWIW imagine a rack and pinion immersed in a moving chunk of butter. The rack is anchored, the butter flows like wind, and the pinion is connected to a corkscrew so it can only move if the corkscrew turns forward through the butter. Maybe some clear jello would also work and make the process visible. Of course it's difficult to imagine the pitch of the corkscrew being in the direction of it turning forward in the direction of motion but the high pressure side of it is determined by pitch vs speed.
Sorry it's a late comment and probably a repeat of a previous one by somebody else.
BTW if a jello model were attempted maybe put red jello behind the gadget and green jello in front of the gadget. When the jello moves forward a working gadget will corkscrew into the green jello.
3D printed parts and some jello, it could make a good school project.
Heat might be warming, but is not enlightening. ;-)
@James H did he kill himself because of the rocket or because he proved himself wrong?
The more Veritasium physics videos I watch, the less I understand how I passed physics in college
@your average cultured human yes that is spot on just like a beach buggy or sailing boat but only as fast as the wind speed pushing it ,,,,,sailing boat will not go faster than the wind if the wind is behind them they have to go across the wind to go fast ....if the wind is behind them and they want to go in the same direction as the wind they don't go across the wind then as they wont get any further in the direction they want to go even though across the wind is faster as they have to tack.,,,,,,,,,this kart has to go strait down wind or it is not going doing what they said it is.....thanks for the reply
I failed physics in college but I understand everything its because college is WRONG and I am a genius lol 😎
@Daniel Rønjom If you did do physics then you would have been told the basic stuff like you cannot get something for nothing .
@191246mann1 yes I understand these things. well not exactly where the energy goes ofcause in this situation and others or where it comes from, like there is a lot of soundwaves in wind too, isnt it, Ive been thinking a lot about soundfreequencies lately. but since I didnt study physics I come up with a lot of stupid ideas lol. like for example, that the windmills on the vehicle quietly collect sound waves from the wind, in front or in back or whatever who knows. but then it wouldn't work with a windmill on a treadmill. its all about black matter I guess 🙂
@Nuiun 04 Thanks for the book reference.
This is totally the post-apocalyptic extraplanetary desert science-fantasy vehicle of unfathomable awesomeness.
I'm pretty sure I remember this race/chase scene from the second MaddMaxx movie??😜
I love how science has been perverted into an "if I don't understand it, it must be impossible" paradigm. We all need to be more humble. Two sailboats tacking on a cylindrical earth....brilliant!
Nikola Tesla thought that we will never be able to harvest nuclear energy, and he was one of the most out of the box thinking inventors of all time. Here we are, 70+ years since we harvested fission and we are on the brink of cracking sustained fusion as well.
Ughhh...I still dont get it. I watched both of the videos multiple times and I don't understand it at all ....this is so hard. I'm probably just a dumb dumb
@Escaping The Norm A god-of-the-gaps is a very useful tool for keeping the world less intimidating (but not safer). I think it has a useful place in society (just not everyplace).
@Lofi Anorak no I'm in the same boat as you. Have you taken a physics class yet? Maybe that's why we don't understand it
@Nathan in highschool, yeah.
This is a very good reminder that science is about creatively answering questions. Congrats to the team who theorized and built the blackbird for using creativity to do what looked impossible to me few minutes ago.
However, it would also be good to say that it is not their theory and that they are not the first ones.
@Frank Berninger still, either way they ended up proving the theory, even if they weren't the first to come up with it
Man, the explanation of "if the earth was a cilynder" was so straightforward.
😅😭😂
@Thomas O'Neill that’s because the keel of the ships allow the sails to exploit the wind in a way that that allows it to travel faster, a windmill/pinwheel on its own doesn’t exploit the wind in that same way. The propeller the way it is designed here allows it to exploit the wind in a comparable way that the actual design of the ship allows the sail to exploit the wind in the ships analogy.
@Thomas O'Neill If the wind pushes it to make power, it's a turbine. If it uses power to push the air, it's a prop. Does it drive the wheels or do the wheels drive it?
@Thomas O'Neill it's acting like a sail in reverse
he said that qnd my mind went puuuuufff
I had the same problem happen to me in a middle school science class… teacher asked if a plane could lift off if it was on a treadmill going backwards as fast as the plane going forwards. If the speed came from the propellers and not the wheels then it shouldn’t matter if the wheels were turning backwards…
I was the only one in class saying the plane would lift off. Interesting thing (taught me a lot about people) is that I got threats and was even on the receiving end of violence when I would not change my stance.
When we watched a mythbusters video that showed the plane did lift off they still wouldn’t believe and continued to threaten and bully me.
Perhaps the most dangerous people in our society are the ones who think they know and will not listen.
It will only lift of if there is enough friction between plane and treadmill, because only then the props can move enough air around the wings without the plane going forward. I think...
Fast sailboats, iceboats etc. have for a long time (100 years? in case of iceboats0 have beat the wind down wind, by tacking as you show in your video. What this machine allows is to "average out" those tacks internally and go st. downwind. (Thought experiment: consider two boats on opposite tacks each towing with a line reelling out, a boat in the middle, when reach end of line tack. Entire system goes straight downwind.)
Or even simpler, sails or props act like wings with lift...not "pushed' by the wind.
Those people who in the past made leaps forward in science and physics and engineering were often told your wrong, your a fool, but it's only because the doubters didn't have enough knowledge, understanding and grace. Great job to all concerned. ps I don't understand it either but it did go faster than the wind. God bless
Always love when people prove other “know it alls” wrong
Experiments made out of spite to prove people wrong is the best kind of science
correct
Thats 90% of science. The other 10% are accidents.
This is the way.
Wasn't one of the first experiments done to prove the earth rotates done because "those in charge" said it didn't?
@xUNHEILv SNIPEZx Used to be the way in the Doom modding community. Now there's advanced Doom source ports and modding communities that can do almost aything, but back circa in the 2000's the community was small and pretty set in it's ways in some areas. Some guy said he was going to mae higher-resolution sprites by "just stretching them and adding noise in Photoshop". Pages of posts saying it couldn't be done, even after he'd posted pretty-damn-good looking results.
The whole concept clicked into place for me when you said “it’s a fan blowing against the wind”.
I can understand the fan part. But what powers the fan?
@J Yao The wheels do. It’s not what one might think at first glance, that the wind blows the fan, which powers the wheels - but the other way round. Wind pushes the entire frame of the vehicle, wheels put the fan into spinning, which pushes air back. Therefore total speed is wind speed plus the extra gain created by fan blow (minus friction loss).
The concept clicked to me with the two sail boat on a cylinder Earth example
@Blechfuchs What I really don’t get about this is what the hell was the point of him explaining the sailboats to describe this thing? Two sailboats being pushed by the wind, their sails being analogous to the props, spinning on that “cylindrical earth” as he put it, the same rotation as the props though. I just don’t get what the point of that was if that’s not even how the damn thing works
@mepath right? but I think what some people are missing is the two boats on the cylindrical earth aren't moving unimpeded, their movement is based on a relationship between the pushing wind and the drag of the sea through which they move. Tacking seems to use not just the wind, but relationship between the wind and the water
I am 42 years old. I clearly remember that as a child, I often laid in the grass and watched the sky. One thing I always paid attention to was how when a airplane flew I could always watch the end of it's contrail disappear at the same rate as the airplane moved. The length of the contrail varied but the fact that it always disappeared at the same rate as the pane flew always caught my attention.
That really depends on atmospheric conditions in the flight path. Mostly relative humidity. Under some conditions, there would be none, and others, the con. trail would be almost permanent. As conditions change along the flight path (as they usually do), the length changes (getting shorter or longer, but usually I think it would change fairly slowly).
@you2tooyou2too No. I clearly remember. The contrail Always! Disappeared. The changing element was the length of it before it started disappearing at the same rate as the airplane moved. It was never really long enough to cover hardly a quarter of the visible sky. Give or take a little but no. You are wrong. Hard to accept I'm sure but your statement is false.
Loved it!. It immediately generated a couple of questions. Was the gear ratio of propeller to gearbox to drive wheels 1 to 1?. And what if you changed the gear ratio, or increased the diameter of the drive wheels? Would the output speed of the craft increase exponentially?
I love how simple questions and problems produces so beautiful answers and solutions. What a time to be alive
this is going to become a trick problem on a physics exam.
@saifeddine ALOUI there is no trick, this works because you're just converting energy from the wind into forward momentum for the car. It seems counter intuitive because at first you think the wind is just pushing the car but in reality the propeller is pushing the car and is extracting wind energy and converting it to torque at the wheels. The wind is pushing on this vehicle and the entire time it's accelerating the torque at the wheels is being added to the propeller and as air is passing over the propeller it's both extracting energy from the air and adding torque to the wheels.
Imagine the propeller was not tied to the wheels but tied to a generator. The wind would still push the cart forward and the propeller would still spin. Eventually the wind would impart enough energy to move the cart at roughly the speed of the wind. Could you still generate electricity with the propeller? Instead that energy is being converted back into more momentum/linear energy for the cart because of the transmission connecting torque at the wheels and the prop.
Me seeing this on my AP-Physics Exam: T-T
actually, it will not be a trick problem for those students who apply a little common sense and really think about it.
Just getting my comment in here before 500 comments.
Not if you study physics in the university of bollywood.
While at college 43 years ago I saw a fellow student with a small catamaran model with a small propeller below linked to a large propeller above put his model on a small pond with almost no wind and it accelerated across so fast he could hardly get to the other side fast enough to catch it. It was magical, and now I know why. Thx.
@masterdolphin 35 🤣
@masterdolphin 35 The point is that the boat would be able to sail directly into the wind,like the catamaran model and full size catamarans that have been successfully built and sailed.(one of which I have seen sailing on the English east coast.)
@Stephen Crowther the thing is that normal sailboats are so good at going in most directions that adopting that technology would prove expensive and unnecessary, but its cool that you have seen it, what is the name of that catamaran?
@BubboPants I asked that before: I'm pretty sure it would work upwind also, but not as fast. The wind would have to drive the air propeller, to drive the water prop, to overcome wind and water resistance.
The hand lever controlled the pitch of the air prop. If it could luff, could it slowly add pitch without adding much wind resistance, but providing significant water prop thrust?
If that applies to the land-craft, why didn't they do that too: drive in circles? I don't know.
Why did my single post show up several times? :-0
"I'm going faster than the speed" what a legendary fun fact about yourself to say. You are a legend bro! I'll call you my hero now!
Oh I finally get this. The wings turn because you move forwards. The wings then generate lift in the forwards direction which makes the wings spin faster. Nice
I love how you can demonstrate something and people say that it can't be possible.
How many gallons of snake oil were needed to lube the chain that connects the wheels and propeller. j/k
Thanks for providing videos like this.
Damn the explanation with the two sailboats was amazing.
I actually didnt get that
Wasn't
The cart does not work on the principle of the sailboat example. In case of the cart, the propeller (sail boat) is pushing the wind backward and not the other way around.
i don´t get it..... this thing is total useless ....🤥
@fatsquirrel75 The sail is an airfoil (similar to a plane wing) - when moving diagonal to the wind, the shape of it generates high pressure in the back and low pressure at the front. Pressure differential generates forward momentum (or lift in case of an airplane) with less drag than if you would to sail straight down the wind.
@Kakss It is not contradicting it because it does same thing, but only in reverse - propeller pushing the air in the opposite direction to the wind creates a high pressure in back, with low pressure in front of it.
Tge way he describes it at the end really helps, because it defines how this craft isn’t adding energy to the system, and instead just takes more energy from it’s environment through an unexpected way. At first, i was thinking that the extra drag brought on by the wheels driving the propeller would zero out any extra push that the spinning of the propeller would bring, but considering that the propeller’s push is taking energy from the wind by slowing it down past reaching equal speed to the wind, then it stands to reason that the craft not speeding up would essentially be a destroying of energy, as the speed of the wind behind the craft being slowed wouldn’t actually be doing anything otherwise, essentially that energy would be disappearing if the craft didn’t speed up.
The model in your hand probably would have worked more efficiently and much sooner had you mounted the propeller in the proper direction. The way that is geared the prop spun backwards for the design of that particular one when you rolled the model forward.
The way to understand this more easily is to call the wind what it really is: A FORCE!
If you are a solid object and you are blown by the wind, you of course will stop accellerating when you get to windspeed because you LOSE YOUR FORCE! That's why sailors use the OPPOSITE FORCE of the "solid" sea to hold them "in place" against the wind, and glide sideways! Then you never lose the force of the wind, and (if there was no drag in the sea) you could go a miilion times the speed of the wind!
It is the same with the propeller: It is also moving sideways through the air! And thus producing force to the axel by more factors than the mere windspeed. The area and pitch also come into play. That way it can harvest energy and produce force, even when the vehicle to which it is attatched is moving faster than the wind!
Derek, you are one of the most curious individuals I know. And you try to unravel things that seem obvious but are not. I always enjoy watching your videos so so much.
"If I put two sailboats, that's a prop" that explanation was mind-blowing.
Hahaha ….I was thinking exactly in the same way… amazing!,
@Decision Scientist it's easy to conceptualize if you ever pinched watermelon seeds. They can shoot out fast even though your fingers move slowly. One finger is the wind in the sail and the other fi ger is the keel in the water.
@Mathias Vofrey except that the prop comprises two sails/wings which are traveling ( tacking) across the direction of wind travel.
"Was that after the first acid tab or the second?" Lol
@Unindicted Co-Counsel Precisely
Even after seeing the more detailed video about this, I'll just categorize this into the "okay I accept it, but I do not understand it" section in my brain.
Yeah, a direct explanation is a little complicated. You can't start with the wind making the propeller turn, because it would turn it the wrong way. You have to start with the wind just pushing the propeller forward, and that pushes the whole cart forward. The propeller doesn't start turning until the wheels and the chain start driving it, and that doesn't happen until the cart makes the wheels turn by forcing them to move forward.
It's trivial to understand if you ever rode a bike.
Inb4 driving faster than you're pedaling? No way.
Hi @RagingGeekazoid . Yes indeed!
As we Understand the same this part, would You be Kind Enough to Review my Full Explaination in the Main Thread I have just posted? Please 🙏
This is the rational person's reply, as opposed to the far too common "I don't understand it therefore nobody can understand it, and it cannot be true."
thank you so much to the animator for the boat reference! It would have bugged me so much if the waves were the wrong direction. love the videos, please continue with the amazing intuitive content!
You can tell that veritasium is such a good YouTuber by the fact that he leaves ads for the end of the video
The key element in the sailboat in a cylinder world reference is the water. The forces of the water (buoyancy and resistance) on the boat's hull is essentially what permits faster than wind speeds (albeit never strictly downwind in the case of a sailboat). This is where the leverage comes from.
The propeller-gears-wheels in the vehicle act in the same manner. In other words turning speed into torque for the fan.
There is no way this vehicle could go faster that the wind downwind if it weren't in contact with the ground.
The inventor must have been grinning so hard in that shot where he's holding the wind sock. Basically got the best shot possible with great equipment that he was right all along.
@gt gt I understand where you are coming from. However, I respectfully disagree in the fact that when you watch a bit more the gear had gotten stuck and not actually removed. You can also observe that there is a moment where it does in fact go the other way. I think that Veritasium has been supporting his arguments with the wrong facts, but I do believe that you are right if there are no wheels and gears it would spin in the other direction. Now, nothing in that video can be used to prove that there is or isn’t an is or isn’t an engine inside of the machine. I know that the theory works because I have made one of the small ones and used it in the wind. However I also found that there is a weight limit according to propeller size and wind speed. This limit has shown that at 10 mph winds that they were saying were healthy and what I’m guessing is a 15 foot propeller the weight limit is around 500lbs, which seems extremely improbable. On a small scale when you don’t need to make space for something to ride you can make something around a foot long and 8 inches tall that is around 6 ounces. It becomes a large problem when you need to scale it up that large. I do not think that they could use aluminum for something that size where it isn’t hollow. Personally, this seems fake to me. Until there is a video with a full build and some sort of proof behind the theory, I do not think that this would work with a human on that scale. I think it would also work with pine wood although it is not extremely sturdy which would explain the shaking. This is a theory that works and has been proven. Scale is the factor that matters, and potentially the honesty and integrity of the humans creating it. People are greedy and do a lot for clout and money. I don’t think that these people mean for that in any way, but nothing matters for now as long as it is a theory and not a law.
(please excuse grammar and misspelling. I have typed this on a phone)
@Ronald Mcdonald Hey.. thanks for the long reply... this video has lots of comments and they get lost. :)
I clearly retracted my words on all my comments - this is not a fake. I missed the wings angle detail at 4:03.
The angle of the wings is variable. So if you blow in that "fan" from behind (no wheels, no gears), it will still be able to rotate in both directions (clockwise and counter-clockwise), depenind on the angle of its wings.
All fine, great mind-blowing :) project!
@gt gt The blades pitch angle was actually adjustable
dude there are a lot of people who didn't totally understand it and that is okay. but insulting isn't. If you did understand the concept and still questioning it then we'd respect you. Right now you sound pathetic. I felt sad for realizing the presence people like you in society.
16:36 ... I needed to know what was this dirty windsock talk all about. [The windsock was not dirty and neither was the man operating the windsock. And then you realize, he is driving Against the wind!]
It's good to exercise the mind by challenging held assumptions. I hope someday the overunity engines can be tested by open minded people like this
This is the best science content I have watched in YouTube. The dedication and efforts to make it is astonishing. Happy to see potato jet taking care some of the visuals.
There's an old expression that I was exposed to by my favorite movie Master And Commander, "run like smoke and oakum". It's used as an order to sail as fast as the boat can go but it took some digging to figure out the real meaning. Smoke and oakum are basically smoke and ash that comes from a wood fire on a sailing vessel. So to "run like smoke and oakum" would mean to go so fast as to match the speed of the smoke being taken by the wind, to sail as fast as the wind carries ash coming off of the ship.
To a sailor, the idea of exceeding windspeed dead downwind just seems wrong! But the two sailboat analogy for the propeller was useful!
Instead of "Sailing DDW" the propellers convert that wind angle into a deep reach, where fast sail boats actually can greatly exceed windspeed and can in fact exceed windspeed to leeward.
You've nailed it perfectly
The way the creator explained the prop mechanic of a "cylindrical earth" is mindblowing, and that kind of out of the box thinking is the mark of a genius.
@zan no, they actually think the earth is flat
An explanation that omits the crucial fact that the propeller is connected to the wheels is not an explanation at all.
Compressed air by the propeller and thus a cylinder is also a compression situation
This right here
Yea I thought the same
Easyer to understand if you consider the wind as a vector field. In other terms: wind it is a mass (of air air) that is moving. We can catch this energy and use it to do what we want: from grind grain to move something ;-) .
You could also think of it like this: Imagine this vehicle standing in completely still air. If you push it forward, it will begin to rotate the propeller to continue pushing it forward. In a perfect world (no friction losses, etc.), the vehicle would then continue forward indefinitely at the same speed (perpetual motion), but the world's not perfect, so it slows to a stop. But if the wind from behind is exactly strong enough to compensate for the friction losses, the vehicle would continue at the starting speed, even though the relative speed of the wind is lower than that of the vehicle. but if the wind is strong enough to add forward thrust, the vehicle will accelerate forward.
The “throttle” is a screwdriver shoved into a pice of square tubing.
Man that’s got some MAD first Honda Civic feels to this…
The faster you go the better the effect should be, the velocity of the air being pushed by the propellor is added to the wind velocity to determine thrust. Super cool demo, one of the best.
that idea of the cylindrical earth and two sailboats being like a propeller was genius
@someting lol the term snowflake was invented to make fun of the egos of people like you. Look it up.
@someting the guy wasn't saying the earth was cylindrical did u even watch the video clearly states the earth is a sphere it was just his thinking of moving forward faster and it being like a propeller
@someting you could have built your own channel dedicated to refuting "idiots" and proving that you're above us. Use your physics degree to conduct actual experiments instead of ranting against "these idiots" on youtube sections. That way you can make money off of your "physics degree"
Screw Flat Earth theory cylindrical Earth theory
Definitely! The same kind of thinking helped us figure out rockets and special and general relativity.
i knew it had something to do with the warped propeller. and I suspected that its warped nature gave some sort of extra push, but I never thought that it was possible to gain more speed by just going sideways like the ships illustrated. interesting
Everyone always shuts down great ideas because they "Seem" to break the laws of physics as we understand them.
If some method of creating "infinite energy" is ever concieved, it will be in the garage of a dreamer, not in the lab of a professor.
This could have only happened outside of an University. Genius!
what if the "contraption" creates a difference in airspeed, speed of air, where the "telltale" points back... maybe even by a gust of air. I think in order to show this, you have to actually measure airspeed and vehicle speed at the same point in time down the track. The propeller might act
like a flywheel, but physics wise, it, wind, cannot put more energy in to the contraption to move it forward than it needs to. That's just the physics law of conservation of momentum/energy.
This was just a short demonstration video, not a 'proof' of the concept. Research the Blackbird and you'll find that to set its 4 world records, all aspects were instrumented, recorded and observed by qualified independent third party observers.
It violates no natural laws.
It's not breaking the laws of physics, it's breaking the laws of understanding.
I think, in the ground reference frame, the cart is accelerating to catch up with the wind ahead and extract energy. There is no violation of energy conservation. This is unlike a sail boat that cannot accelerate past the speed of the wind. So, from energy perspective, the kinetic energy (translational and rotational) of the cart is continuously increasing. However, in the reference frame of the wind, there is an apparent violation of energy conservation at first sight.
@NuclearBolton (re: "... adds extra inertia ...") Isn't inertia a property of mass? So in order to have more inertia, wouldn't that require more mass? Inertia is the resistance to a change in velocity, no? The more inertia a body has, the harder it is to change that body's velocity It's been a while since I took Physics, but that was my understanding (which, of course, has at times been faulty).
@Charly M Rivera (re: "science = 0, god =1") You're comparing apples to oranges. "Science is proof without certainty. Religion is certainty without proof." Science answers questions that can be proved or disproved by evidence. Religion answers the questions that science cannot. There is no overlap.
Best answer to this and most things in life. How many understand how a microwave oven works but use it without question. It heats food without heat and will only become hot from the heated food??? 🤯
@Charly M Rivera science is a million times better than religion because we strive for facts and don't say sky daddy did that.
So, it's like a chain reaction or a circle logic, somehow. The more you move the wheels, the more the fan rotates, the more the fan pushes the air behind and the more it moves the wheels, and so on... Beautiful.
I want to see a new version of that thing built that would be sick!!
Excellent explanation. YOU are a much better teacher than the "professors".
Veritasium - 2021-06-01
If you want more detail on the explanation here it is:
1. The car is powered only by the wind. There is no motor or batteries of any kind.
2. The propeller does NOT spin like a windmill. The wind does NOT push it and make it turn.
3. Instead the wheels are geared to the propeller to turn it the opposite way, like a fan, so it pushes air backwards.
4. To start the vehicle the wind simply pushes on the whole vehicle (like a block of styrofoam) and gets it moving.
5. The wheels are turning so they turn the propeller in the opposite direction to how the wind is pushing it.
6. The prop is pushing air back so air pushes the prop forwards, accelerating the car.
7. Once you get up to wind speed there is no apparent wind on the vehicle. If the prop were spun like a windmill this would mean no more thrust. But, since the prop is operating like a fan, it still accelerates air backwards, generating thrust.
8. You can go faster than wind speed continuously because even when going faster than the wind, the prop can still accelerate air backwards (in the car's frame of reference) generating thrust. In a stationary frame of reference you would see that the wind behind the propellor is slower than the surrounding air. So it's clear that the energy is coming from the wind.
FAQ: If power is coming from the wheels to turn the prop, why doesn't that slow down the wheels more than it gets the prop to push back?
A: Because the wheels are moving over the ground much faster than the prop is moving through the air (because there's a tailwind).
Example:
Let's say the car is going 12m/s in a 10m/s tailwind, so faster than the wind (note the prop will be moving through an apparent headwind of 2m/s).
Power = Force x Velocity
Let's say the chain applies a drag force of 100N on the wheels to drive the prop. This means we're taking power from the wheels = FxV = 100N x 12m/s = 1200W
If we apply this power to the fan, it can create a force of F = P/V = 1200W / 2m/s = 600N
Admittedly I've assumed no losses, but even if we waste half the power, we'd still get 300N of thrust which is more than the 100N of drag the prop adds to the wheels. The key is that we're harvesting power at higher speed, lower force, and deploying it at lower speed, higher force (which is only possible because we have a tailwind - in still air this wouldn't work because the relative velocity of the wheels over the ground would be exactly the same as the relative velocity of the prop through the air).
Bubba Hottep - 2021-11-30
@greenkid336600 or else they kludged together their cart from available materials and used the rear sprocket from a bicycle and put the chain on whichever one fit. 😬
Bubba Hottep - 2021-11-30
@OficjalnyKrwiopijca I'm thinking there's only one source of energy there- the wind.
Interestingly, when scientists measured the air pressure on the top side of an airplane wing,they did not find a vacuum there. It was not a bernoulli vacuum creating lift, but the action/reaction from "throwing" a buttload of air molecules down that caused the airplane to fly.
Guy Laurant - 2021-12-09
Are there any academics who publicly proofed them wrong after the publications of this video.
Dean Z - 2022-02-23
Hi @Veritasium , big fan, love your video. One question about the sailboat though. You said the reason why a sailboat can go faster than the wind is because when the sail curves forward, the air flows faster in front that it does behind, which creates a lift force pulls the boat forward. But the sail will only curves forward when it travels slow than the wind on in wind's direction, right? So when it travels faster than the wind and beats the balloon, the sail shall curve backward right? Then it will not be able to create force pull the boat faster than the wind. This is my understanding on the sailboat part, not sure where I went wrong?
Ryan Lynch - 2022-07-02
@Eagleizer I think there would be a limit. if you're reducing the wind speed directly behind the blades relative to the wind all around, then once you've reduced it to 0 relative to the ground you've prob reached max speed. theres no more difference to steal from or convert. as long as you have a differential you'll be able to accelerate to higher speeds. I hope some one can answer this because its the best I got without doing any research haha