A Physics Prof Bet Me $10,000 I'm Wrong
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A UCLA Physics Professor bet me $10,000 that my video about going downwind faster than the wind was wrong. This video is sponsored by Brilliant. The first 200 people to sign up via brilliant.org/veritasium get 20% off a yearly subscription.

For more information about the Veritasium Science Communication Contest check out -- ve42.co/contest

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The wager agreement: ve42.co/wager

Prof. Kusenko's slides: ve42.co/Kusenko

My rebuttal: ve42.co/rebuttal
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Huge thanks to Xyla Foxlin for building the model cart, and making the instructions so accessible to the public. Check out Xyla's video -- isdowns.info/lift/u4zKmqJ5qGh4ptE/v-deo

A massive thanks to Bill Nye, Neil DeGrasse Tyson, and Sean Carroll for witnessing the signing of the wager.

A huge thanks to Prof. Alexander Kusenko for being a man of honour -- it's a difficult thing to change your mind, especially in a public forum.

A huge thanks to Prof. Mark Drela for the interview and help making sure we got the physics right.

A massive thanks to Rick Cavallaro for making Blackbird, all your insights, analysis, data, and general help with these videos -- it was so fun to work with you on this crazy project -- check out Rick's channel ve42.co/Rick

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References
M. Drela. Dead-Downwind Faster Than The Wind (DDWFTTW)
Analysis (Jan 2009) -- ve42.co/Drela

2013 AAPT United States Physics Olympiad Semifinal Exam -- ve42.co/AAPT2013

Rick's treadmill footage -- ve42.co/Treadmill

Rick's multiple explanations of how Blackbird works -- ve42.co/DDWFTTW

Blackford, B. L. (1978). The physics of a push‐me pull‐you boat. American Journal of Physics, 46(10), 1004-1006. - ve42.co/Blackford1979

Ruina corrects errors in the above paper: ruina.tam.cornell.edu/research...

Forum discussions -- ve42.co/forum Blog -- ve42.co/blog1 and retraction ve42.co/BlogRetraction

Bauer, A. B. (1969, April). Faster than the Wind. In First AIAA Symposium on Sailing. -- ve42.co/Bauer1969

Bauer's Obituary -- ve42.co/BauerObituary

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.


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Special thanks to Patreon supporters: Mike Tung, Evgeny Skvortsov, Meekay, Ismail Öncü Usta, 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

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Written and Edited by Derek Muller
Animation by Mike Radjabov
Manim equations by Jonny Hyman
Filmed by Emily Zhang and Raquel Nuno
Music from Epidemic Sound epidemicsound.com and by Jonny Hyman
Additional video supplied by Getty Images
Produced by Emily Zhang, Petr Lebedev and Derek Muller

Ummæli
  • Fabrizio Brutti
    Fabrizio Brutti

    But... If that's true, if the trust force created from the fan is higher than the wheels friction, wouldn't the black bird move, once it's started, without any wind? Wouldn't that be free energy? Isn't it impossible? Or I missed something?

  • SCARLETBIRDS
    SCARLETBIRDS

    also i could see this being the new way we force our scientists to actually look at facts instead of shunning them in favor of not rocking the boat every time we get new theories, could greatly speed up research and progress being actual money would be on the line forcing people to prove what they say, it definitely worked here

  • SCARLETBIRDS
    SCARLETBIRDS

    always called this vertical ground effect, basically a cushion of lift between opposing areas, the air pushing against the blade pushing basically helps the unit work optimally the same way ground effect planes get their boost of lift, the machines will work as shown but moving air is much more effective, pretty sure planes flying with the wind also benefit from it greatly as well for a speed boost now we just need more ways to apply it both with and without wind, inb4 new sources of power and high efficiency lift in planes are discovered making the cost on fuel drop greatly, always more applications once we fully understand something and get creative

  • Forever in a moment
    Forever in a moment

    Please tell me who lost 10 grand 😂

    • Forever in a moment
      Forever in a moment

      @Rick Cavallaro 🤣🤣👍

    • Rick Cavallaro
      Rick Cavallaro

      The one that lost the bet.

  • Wil Young
    Wil Young

    I'm not going to go through all 41,960 comments to see if this has been put forward. So if it has forgive my redundancy. Toss out all your equations just look at it from a practical view point. It all depends on how energy is getting into the system to make anything move. In the case of the cart on the non-moving ground in the wind the energy input comes from the wind blowing through the prop. With the cart standing still, when the wind blows through the prop the prop will turn in the direction that it would if it were turning to blow the wind in that direction. That is, if the wind is coming from behind the prop will turn in the direction which would blow the wind forward. Now, if the prop is geared to the wheels to make the wheels move the cart forward the wind will appear to be slower relative to the cart and the prop. As the cart speeds up the relative wind will become less and that lesser relative wind will add less energy to the system. Now the system (cart) has friction losses in the wheel bearings and the rolling friction of the wheels on the ground. So the cart will gain speed until the decreasing energy caused by the decreasing relative wind just balances the increasing friction losses caused by the increasing speed of the cart. That will be long before the cart is moving at the speed of the wind. The cart can go no faster than this equilibrium point. As for the experiment on the treadmill, the energy being injected into the system is coming from the treadmill belt moving relatively to the cart driving the wheels, not from any wind driving the prop. In fact the prop is expending that energy entering through the turning wheels to make the cart move relative to the still air surrounding it. This experiment is bogus. It does not simulate the conditions of the cart on solid ground being effected by a wind. Try setting the cart on the gym floor and blowing on it with a fan. Now let the mathematicians figure out the equations.

    • eyytee
      eyytee

      "if the prop is geared to the wheels to make the wheels move the cart forward" It isn't. Have you even watched the video?

  • Georgy Е.
    Georgy Е.

    Theoretically you are almost right, but you are missing the resistance components in the wheels and the propeller, which would be the main problem for the drawbacks. Also you have two sources of energy that are affecting the movement - inertia and windspeed, while you're comparing it with the wind speed only. If you put multiple power sources to one device and compare the output power of the device with one of the sources, of course it will show higher device power.

  • first man
    first man

    I don't think you should have put the professor''s email in the video.

  • Roy Tore
    Roy Tore

    For judges I used Bill Nye the fake scientist guy and Neill Tyson, interrupting lightweight philosopher

  • David Mckinney
    David Mckinney

    Wow cluck bait for days no actual footage what so ever bro in my opinion shat video like were was the legit showing instead of yall just talking physical proof better like get outside and do it quit talking about it

  • Deecon YT
    Deecon YT

    I ain’t even finished high school and here I am listening like I understand.

  • Mr New
    Mr New

    Now here's the true scientific question, will a giant plastic model like the one the chick made work better than the one you built at full speed? or will hers fail other than yours?

  • ffggddss
    ffggddss

    Great story, well told! But what surprised me most in this video is that you managed to get a degree in physics without getting introduced to Langrangian mechanics! As a math major I took, as an elective, an upper-level undergrad mechanics course from the physics department, where we learned the Langrangian (Principle of Least Action) and Hamiltonian formulations of Newtonian mechanics. In fact, the latter is key to understanding Schrödinger's Equation, when you get into QM. (BTW, it was stressed to us in that course, that these aren't new physics, they are just new ways of putting Newton's Laws of Motion into mathematical form; they are mathematically equivalent to Newton's 2nd Law of Motion. The reason for doing this, as I'm sure you've seen by now, is that it actually simplifies certain classical physics problems, as well as giving fresh insight into them. And the reason for not jumping right into them in introductory physics, is that they involve prior knowledge of the calculus of variations.) Fred

  • ffggddss
    ffggddss

    "Today's Challenge" at 16m52s: It actually IS easy. The thought-process is fast; the explanation of the thought-process takes much longer. First of all, the spin direction alternates with every move to the next gear, so the final (light-grey) gear turns leftward, same as the initial, yellow gear. OK, then because every "transfer" simply goes to the next gear, and there are no multiple gears on the same shaft, you're just multiplying all the successive gear ratios, with each successive number of teeth in the denominator in one term, then in the numerator in the next term, so that every tooth-count cancels except the first and last. IOW, the only things that matter here, are: 1. Whether the number of intermediate gears is even or odd - even will make the final gear turn in the opposite direction; odd, as in this case, will make it turn in the same direction, and 2. The tooth-counts of the first (30) and last (60) gears. So gear 1 with 30 teeth, turning left at 10 rev/s, propels gear 9 (the last) with 60 teeth, leftward at (30/60)·10 rps = 5 rps. As a bonus fact, we not only didn't need to know the tooth-count of the blue gears, we didn't need to know the tooth-count of the dark grey gears, either! Fred

  • Locky Law
    Locky Law

    Thank you for all these awesome videos!

  • kohlrak
    kohlrak

    I think that the reason behind this problem is the automatic assumption that we're talking about a "free energy generator," or, rather, that's what people *THINK* it is. Our gut response to this is to call it out, and it seems like an easy bet. The mistake was, however, that this was not a free-energy generator scam, no matter how much it looks like that on the surface, so it is a really, really tempting target, and an expensive one, at that.

    • Rick Cavallaro
      Rick Cavallaro

      You're exactly right. And that's precisely what I was counting on when I posed it as a brain-teaser. Of course I never wanted to convince anyone that perpetual motion was possible. On the contrary. The derivation and solution to this demonstrates that it's not the case. What's more surprising to me is that people refuse to see it any other way even when you warn them ahead of time that it's not perpetual motion, and there are no claims being made about it that would suggest it is.

  • Babos T
    Babos T

    awesome. I was with you from start thinking what you later explained. And damn you explained it so well and your experiments are so on point. love it

  • Chris M
    Chris M

    I would like to see an analysis of how the Mythbusters blew their own sail and achieved forward acceleration.

    • eyytee
      eyytee

      Look for thrust reverser force analysis (jet engine). It's the same principle.

  • ChillinRazta
    ChillinRazta

    These guys are stupid, they are both technically correct in both their theories,

    • FlyNAA
      FlyNAA

      Kusenko claimed that the vehicle can not go faster than the wind with a non-negative acceleration, and he was squarely incorrect about that.

  • ChillinRazta
    ChillinRazta

    Just go straight to the point

  • ChillinRazta
    ChillinRazta

    Why bet just brainstorm together

  • ChillinRazta
    ChillinRazta

    Click bait for the bet

  • fxengineering
    fxengineering

    It is common for racing sailboats to travel forward faster than the wind speed. it is simple transmission of power with the wind hitting the bias of the prop likened to the tack of a sail.

  • Jeremy Glassford
    Jeremy Glassford

    I would love to have the mental capacity, patience, physics, engineering, and other skills required to do the math, designs, and engineering myself, instead of asking this question for the world, and someone else then doing it and getting the credit for it if it's possible, but: If this works on wheels, could the wheels not be propellers and someone invent an aircraft that doesn't need fuel once it's moving? I feel like it shouldn't work as an aircraft, but then I feel like it shouldn't work as a ground vehicle either, even after watching and tentatively understanding it.

    • eyytee
      eyytee

      "If this works on wheels, could the wheels not be propellers and someone invent an aircraft that doesn't need fuel once it's moving?" See 11:02. You need a velocity difference between two media you are interacting with.

    • Rick Cavallaro
      Rick Cavallaro

      @infinitelyExplosive I've always thought it would be fun to do a similar thing. I'd love to have a hang glider and paraglider (or perhaps two hang gliders) tow each other to altitude by keeping them in separate parts of a strong gradient or some other manner of different air streams.

    • infinitelyExplosive
      infinitelyExplosive

      It would work if you can get the propellers to be in air moving at different velocities. That's pretty hard to find, so it's impractical in reality.

  • Austin Sweeney
    Austin Sweeney

    Everyone just realize that a ISdownsr is smarter than Neil Tyson and Bill nye . He made them look dumb. They are fake....

  • Luis Diego Salas
    Luis Diego Salas

    The fact that a physics professor and you actually are willing to bet $10,000 and can manage to lose that money in the name of science, gives me hope in the sense that there is money to be made in science and research. That doesn't happen everywhere! I loved this video.

    • Rick Cavallaro
      Rick Cavallaro

      There is definitely a very good living to be made in science and research here in the U.S., and definitely here in Silicon Valley. And you can have a helluva lot of fun doing it!

  • mhavock
    mhavock

    also u should fire that other Veritasium person that was 80% against u LOL , just kidding

  • Onur A.
    Onur A.

    Well done mate, WELL DONE!

  • William Levy
    William Levy

    simply amazing .. thkx you tube i waited 28 years for real content

  • SheepHair
    SheepHair

    Get dunked on, doubters

  • Heath Hafemann
    Heath Hafemann

    So why the are we not using this as a power supply 🤔. No really, I want to know it makes more power than what's applied to it. When it reaches a terminal velocity of the device. We could tether them to a point and use it turn a generator.

    • FlyNAA
      FlyNAA

      There's gazillions of those things tethered (actually, simply built as fixed structures) to the ground generating power in windy areas, they're called wind turbines.

    • John Borton
      John Borton

      It does not make any extra power. It's simply a wind powered device. When the wind stops, it stops

  • #CRYPTO BOND 007
    #CRYPTO BOND 007

    Very simple, small pulley aka the wheels supplies power to larger pulley aka the propeller. Very slow to start, but once upto speed will hold speed because the smaller pulley is turning faster creating constant thrust to turn to largest pulley aka propeller. Like a crane lifting heavy goods it will use a larger wheel to make life easier which is exactly what the propeller is, once it hits a certain speed it can only go faster it will not slow down its very simple physics. I'm shocked the professor didn't understand this basic concept.

    • #CRYPTO BOND 007
      #CRYPTO BOND 007

      @John Borton at this point John I feel obliged to tell you as you clearly dont understand physics or pulley systems and propeller physics. you clearly didn't watch the video.... if you put your finger in your ear and spell RED backwards you will understand how the blackbird works........

    • John Borton
      John Borton

      @#CRYPTO BOND 007 Nope, you're not understanding how the Blackbird works. The critical ratio is not between the size of the wheels vs the propeller or even the rpm of each, but rather between the propeller distance over the ground vs the *pitch* of the propeller. We call this the the VSR (Vehicle Speed Ratio) and of course can be designed in properly using any combination of propeller size and wheel size.

    • #CRYPTO BOND 007
      #CRYPTO BOND 007

      @John Borton this whole equation was worked out by calculating wheel speed and size John Please use common sense

    • John Borton
      John Borton

      @#CRYPTO BOND 007 You'll need to study more about how the Blackbird works - If you think the rpm of the wheels must be higher than the propeller, then you most definitely don't understand it yet.

    • #CRYPTO BOND 007
      #CRYPTO BOND 007

      @John Borton no it wouldn't!!!! It's very basic physics use your brain!! You cannot use larger wheels it would not move the propeller fast enough or even get going under small amounts of wind!!!!!!!. The smaller wheels need to rotate faster to spin the big propeller it's very basic!!!!!

  • timmy chang
    timmy chang

    In the past would be appall hearing Neil Degreassy n bill nye name in a same sentence, but since both have the affinity to politicalize their career. Suite themselves.

  • David Thompsom
    David Thompsom

    flat earthers should start a bet for there theorys

  • Florida Man
    Florida Man

    Ok, I'll be _that guy_ Xiyla is stupid beautiful

  • Hessam Mirnezami
    Hessam Mirnezami

    Have you take into account the inertia of the spinning fan itself? Its working like a flywheel and keep energy and releasing it, the fan will charge slowly with the wind and at a moment the fan can't spin faster because it reaches the speed of wind (or treadmill) then the fan releases the energy in it and will help the car go faster. I suggest someone test this with a small flywheel carr and a treadmill to proof this.

    • FlyNAA
      FlyNAA

      The flywheel can only release energy by slowing down, which does not happen.

    • John Borton
      John Borton

      Yes. Was considered from the start. It's powered by the what sailors call 'true wind' (wind over the surface) and nothing else.

  • mvpmickey1
    mvpmickey1

    *Science:* _DIsagreement is not a problem, it is opportunity_ *Society:* _You Disagree? Die on the stakes, and be burned alive_

  • Mantastic Adventures
    Mantastic Adventures

    Awesome way to great movement. I wonder if that same concept can be applied to an airplane?

  • james Trujillo
    james Trujillo

    Majority of stem professors can make 10k in less than 2 months lol. 10k is nothing for him haha

  • Dan Kennedy
    Dan Kennedy

    The fact that the word torque was never used in this whole process kind of annoyed me 😂

    • kohlrak
      kohlrak

      How about addressing that this wasn't a free-energy machine. They could've totally solved this early, without the bet, by pointing out that this isn't what the gut feels like it is.

  • TrailsEnd
    TrailsEnd

    OK, who was right. 17 minutes of gobbly gook, and what was the answer? I like physics and explainations, but who was right. Why complicate eveeything

    • FlyNAA
      FlyNAA

      Answer at 15:15

  • Tomi Selepe
    Tomi Selepe

    I stand with the Professor on this one, or at least until I have as much info as the dude has. Couldnt the same biases of steering be as prominent in the modelling as they are in the determination of wind speed being slower? I dont trust humans and their need to confirm their biases, and yes myself included.

    • eyytee
      eyytee

      @Tomi Selepe "For now I stand with the Professor on his initial objection" In the video description you will find Derek's rebuttal to the Professor's initial analysis, which also points out an obvious sign error the Professor made.

    • John Borton
      John Borton

      @Tomi Selepe Hopefully you'll be more thorough in your investigation than the professor was before committing and losing $10,000.

    • Tomi Selepe
      Tomi Selepe

      @Rick Cavallaro thats the paradox I wish not to entertain. Let me come around to understanding the problem that leads me not to accept this outcome first then maybe I will an answer for you. For now I stand with the Professor on his initial objection. ~

    • Rick Cavallaro
      Rick Cavallaro

      >> I stand with the Professor on this one Kusenko conceded. Does that mean you stand with Derek?

  • INFINITY GAMING
    INFINITY GAMING

    Genius

  • Hélène Honsbein
    Hélène Honsbein

    Me casually scrolling through the comments for spoilers on who won

  • Crypto Secutiry
    Crypto Secutiry

    The happy submarine genomically fax because rest feasibly increase since a nimble gondola. wanting, unusual rayon

  • uakz kah
    uakz kah

    The fast wealth accidentally love because chess inversely branch across a yellow thread. awesome, idiotic hot

  • The Unvlog Channel
    The Unvlog Channel

    Wait. putting a telltale behind the propeller and expecting that to account for wind gradient wouldn't work because the wind being blown back by the prop would blow the telltale back, right?

  • DTDRS
    DTDRS

    Bill is not a scientists sorry

  • Stuart Nicholson
    Stuart Nicholson

    Bill the shill...really!

  • RC Knight
    RC Knight

    Engineers > Theoretical Scientists People who apply sciences have a much better understanding than those who just talk about it.

    • King Pistachion
      King Pistachion

      Ummm no lol

  • Team Wood MERICA
    Team Wood MERICA

    Bill ney…that’s like kaitlen jenner certifying miss America 🇺🇸

  • Da Fedda
    Da Fedda

    The kind of science i like!

  • Thomas Engel
    Thomas Engel

    Is it possible with sunwind?

  • Rock girl
    Rock girl

    "even physics professors can benefit from some lessons on frames of reference" - ooooh sneaky burn in the sponsor plug!

  • Jarmo Hardy
    Jarmo Hardy

    this stil keeps me up at night

  • Mark Weber
    Mark Weber

    Zyla - Brains AND beauty! Does she have a sister?

  • cong truong
    cong truong

    Hi @vertasium, in my point of view, your experient about down wind cart has some thing strange, first, the velocity of the cart is can not measure by treadmill, because the treadmilll only provide drag, not relative velocity with the wind, and also if your cart can go faster than wind, that mean your cart already has more than 100% energy effeciency

    • FlyNAA
      FlyNAA

      @A Myth the power is provided (by the relative motion between air and ground) and the vehicle moves. So what's the objection?

    • A Myth
      A Myth

      @John Borton However now I realize this problem was never a problem of energy to begin with it was a problem of speed.

    • A Myth
      A Myth

      @John Borton I didn't say there is a law of conservation of speed. I said there is a law of conservation of energy. What you see at 13:35 is equivalent to a but a planetary gear drive mechanism with the following exception: 1) The sun gear is also working as a pinion of a geared rack and 2) The ring gear is not a circular gear rather its also a geared rack. The larger roller is equivalent to the sun gear and the geared rack is the wooden log. The ground is equivalent to the ring gear or the geared rack and the smaller roller is equivalent to the planet gears. The force applied to the wooden log is converted to torque on the on the sun gear. The ratio of the speed of the cart to the speed of the log is ratio of the diameter of the larger wheel to the diameter of the smaller wheel. This means if the wooden log where to be fastened to the cart instead of rolling on it, then you will find that you have to provide less force to move the cart at the same speed than what has been provided by the protagonist of this video at 13:35. However you decide to move the cart you will need to provide the same power/ energy (assuming zero losses in all drive mechanism) because Power (energy/ unit time) = Torque x speed = Force x velocity. This is what I mean by law of conservation of energy. Clear as mud?

    • John Borton
      John Borton

      @A Myth There is no Law of Conservation of Speed. See 13:35

    • John Borton
      John Borton

      // " treadmilll only provide drag, not relative velocity with the wind,"// Nonsense. Set the treadmill at 10mph and there is a 10mph relative velocity between the belt and the air in the room. That's wind.

  • Maarten Keus
    Maarten Keus

    Hm idunno man Lmao sorry

  • Mohammed Ali
    Mohammed Ali

    SNATCH BLOCK!

  • Ledfoot 55
    Ledfoot 55

    kool

  • your secret admirer
    your secret admirer

    i love your videos and you but bill nye is a hack job that chases money instead of using science

  • Mats Wederbrand
    Mats Wederbrand

    Funny/stupid that UCLA professor says that you have the highest rate of failing of all in ISdowns. Clearly he (for starting) haven't understood why the propeller is so popular in aeroplanes.... And then combined with gearbox?

  • Demondrive
    Demondrive

    Propeller wings move at an angle to the wind (faster than wind because it's having a resistance to the stream, and the last wants propeller to move with the same longitudinal speed as wind). But the whole thing moves in parallel to the wind. It's just a game with angles

  • Kalepsis
    Kalepsis

    Now apply the solution to space travel.

  • rampaging ibex
    rampaging ibex

    I'm a little bit confused. What gets the wheels spinning fast enough to spin the propeller fast enough to make the car accelerate?

    • Bob OK
      Bob OK

      Faerie dust

  • Daniel Joseph
    Daniel Joseph

    Maybe we can do the same thing with between Bret Weinstein and the WHO on Ivormectin?

    • Rick Cavallaro
      Rick Cavallaro

      Listening to Bret Weinstein about Ivermectin would be equivalent to siding with Kusenko against the Blackbird. But instead of losing $10K, you lose your life.

  • Anthony Buccellato
    Anthony Buccellato

    I haven't watched this yet.... But given velocity and airspeed, aerodynamic high and low pressure zones and temperature of surface vs elevation...potato make great astronauts.

  • bored cat
    bored cat

    The first thing I thought was.. well that has to be related with gears or pulleys... And the fact that he dismissed the whole thing by saying well you cant divide by zero... I Was like damn! Really?..On highschool you encounter that all the time in physics equations... you obviously can't physically reach that 0!! and the answer was on the more detailed proppeller efficency equation... You also said seemingly you can accelerate forever... Well not really, thats why non linear functions have limits..and nothing in reality is linear... its all determined by the proppeller efficiency eq... More factors contribute, Proppeller diameter, Air density, Etc... Man i was amazed by his shortsight... I have to admit the profesor's explaination was compeling but the moment he called the divide by 0 impossibility as an analysis error I was like noo this dude is wrong... I think even Bill was like cmon! Alex! But you edited that part out... Lol I bet Alex is a math teacher... Not a physics one... or at least has a very abstract math background... Still that was a big big fault... I could've compete for the 10k and i didnt even finish college lol... Ill make a wild guess lol when the speed of the car equals the speed of the air.. and the difference results on divide by zero... That would mean you have an infinitely big propeller therefore you have an infinite force lol...not possible right? That doesnt mean the analysis is wrong

  • Aryan Sharma
    Aryan Sharma

    Only scientist can resolve the debate like this. Otherwise it would have title like EXPOSED, LIES, CONSPIRACY yada yada

    • King Pistachion
      King Pistachion

      Agreed

  • Mr. J
    Mr. J

    Ironically I think this is more useful to "dirty energy". Most internal combustion engines work off of pistons with the exception of the rotary engine. This vehicle works because the propeller is so much larger than the wheels. Can a flat rotary engine be configured in a similar way? It would only be practical in trains and buses.

  • Reylan David
    Reylan David

    Wow!

  • Larry Pahl
    Larry Pahl

    dont show that face, your face is perfect for radio, scientific method is selfie free zone

  • Larry Pahl
    Larry Pahl

    you fail to utilize English; therefore, you are always wrong

    • Larry Pahl
      Larry Pahl

      @King Pistachion r u envious

    • King Pistachion
      King Pistachion

      Are you high

  • Ivan Leben
    Ivan Leben

    I think the most astounding result of this experiment is the fact that the bet happened at all - that a well educated physics professor was willing to bet on his own opinion of something, when the truth has already been established in existing literature and is a known fact. That's what is wrong with the world today: even the most educated fall prey to the same human habit of trusting your own opinion and never doing a background check on a piece of information we come across. You state at the end of the video, that what you've learned was that you should work even more dilligently to present proof beyond any doubt in your videos. I am not sure that really solves anything - maybe instead you can use your reach to teach people to invest more of their own effort into confirming the information they come across, as in this case they very easily could have done.

    • King Pistachion
      King Pistachion

      I agree

  • Ben Becker
    Ben Becker

    Put it in a wind tunnel

  • bigcubslover97
    bigcubslover97

    Tyson, a guy that just wants everyone to know how much smarter he is than you and Nye, a failed engineer. Love it

    • King Pistachion
      King Pistachion

      Neil deGrasse Tyson is a great scientist and educator. You're just jealous of him because he's smarter than you.

    • King Pistachion
      King Pistachion

      You are a whole circus

  • Russell Thorburn
    Russell Thorburn

    5:22 That concerned me also. One can accidentally come to all sorts of crazy conclusions if one accidentally ignores the implications of the denominator (e.g. division by zero). "Changing his mind in light of the evidence." If one doesn't do that then one isn't really a scientist. This situation is similar to the question of whether sailboats really can sail faster than the wind on a beam reach (90 degrees to the wind). I've read articles from sailors, physicists and others and there seems to be little consensus even amoung people in the same group.

    • Rick Cavallaro
      Rick Cavallaro

      >> "Changing his mind in light of the evidence." >> If one doesn't do that then one isn't really a scientist. If you read his "Concession" you'll see that he didn't do that.

  • Esa Junttila
    Esa Junttila

    Isn’t this simply a matter of energy absobed by the large propel in comparison to total friction of the system? If the energy is greater, the car accelerates.

    • FlyNAA
      FlyNAA

      It's a matter of the energy transferred to the airmass by accelerating it backward by the prop. If that's what you meant, then yes. But there are a lot of comments about its rotational energy, or flywheel effect, and that has nothing to do with anything.

  • Anthony R
    Anthony R

    Me, a simpleton during the explanation in video 1: yeah, makes sense.

  • Adam Boyen
    Adam Boyen

    Was a wind tunnel test ever done???

    • jonathanjomen
      jonathanjomen

      A reality test (and not just one) has been done. What's wrong with the treadmill? It's the exact equivalent for when the car is at wind speed.

  • DamonDragon1
    DamonDragon1

    Great video! Thank you!

  • Sid Kemp
    Sid Kemp

    This is all cool, and I'd love to see a video with a variant of Xyla's fourth cart, perhaps with geared wheels running on a toothed rail in a wind tunnel with airspeed measured at all heights and widths of the propellor.

  • 3rdBan SubjectNone
    3rdBan SubjectNone

    Why is Bill Nye even here lmao

  • Controlled Chaos
    Controlled Chaos

    I don’t know why someone would bet 10 g’s saying Derek was wrong about a video showing it working. Should’ve bet his PhD instead. The guy couldn’t believe his own eyes or work the problem himself. Guess that’s why he’s a prof at ucla. Just does what he’s told. I’m very happy for Derek that he proved him and Tyson wrong. Nye doesn’t count..

    • Controlled Chaos
      Controlled Chaos

      Apart from Tyson saying Derek is generally more accurate than most in his videos, I didn’t hear him say one way or the other. So we’re both wrong..? 🙂

    • King Pistachion
      King Pistachion

      Tyson agreed with Derek lol

  • John Belli
    John Belli

    Attach a string to the center of the back of the model cart, connect to a scale, read thrust while it is running on the treadmill. I think another way to look at this is the fan connected to the wheels creates a "virtual air-sail" that is moving continuously backwards from the fan and pushing backwards against the wind. As long as this force is greater than the drag of the wheels + headwind drag + the losses from the system, you will continue to accelerate. I'm sure someone smarter than me can come up with an equation that can calculate the maximum theoretical speed given coefficient of drag of the vehicle, rolling drag of the wheels, and losses in the drive train.

    • Rick Cavallaro
      Rick Cavallaro

      >> the fan connected to the wheels creates a "virtual air-sail" that is moving continuously backwards This is a very common misconception. The flow through and around the propeller is identical to that through and around the propeller of a Cessna in straight and level flight. This principle does not rely on the tailwind pushing the vehicle. It relies on the vehicle being immersed in a moving mass of air that provides an advantage to the propeller. >> someone smarter than me can come up with an equation that can calculate the maximum theoretical speed Yes, the formula is actually quite simple. And it shows the vehicle can do a multiple of wind speed, directly downwind, steady-state.

  • David Scott
    David Scott

    Your formulas were ok, but your assumptions of equal force is your flaw.

    • King Pistachion
      King Pistachion

      David Scott you're a whole circus

    • John Borton
      John Borton

      @David Scott: // "I would bet you $100,000 right now, if you want to."// Your wager has been accepted (see your other comment threads). Bob and weave, or back up your boast?

  • Captain Steve
    Captain Steve

    Excellent. I'm not surprised that Tyson and Nye were wrong. Good that you were able to keep the discussion moving. Too bad the "science people" don't allow proper debate and discussion regarding Covid. Google and ISdowns are equal offenders.

  • Kam3loth
    Kam3loth

    I was to lazy to watch all of the video. Who has lost the bet?

    • King Pistachion
      King Pistachion

      @Kam3loth the UCLA professor lost. Derek won

    • Kam3loth
      Kam3loth

      @jonathanjomen Aaaaaarrrrggghhh!! XD

    • jonathanjomen
      jonathanjomen

      I'm too lazy to tell you. ;)

  • J W
    J W

    One thing I don't get with the windmill cart on the treadmill.. there is a guy on TikTok that races cars on a treadmill, and they all go up to the front of the treadmill on their own.. so I'm not sure the windmill cart is showing anything..

    • jonathanjomen
      jonathanjomen

      @King Pistachion So you say - and liking your own comments as well. With an Avatar name like that, who is likely to be the clown? And who if not you didn't check facts? ;)

    • King Pistachion
      King Pistachion

      @jonathanjomen they DO go on their own. They aren't rolling down.

    • King Pistachion
      King Pistachion

      @jonathanjomen the trademill isn't inclined you circus

    • King Pistachion
      King Pistachion

      @jonathanjomen you are a whole circus

    • jonathanjomen
      jonathanjomen

      This guy doesn't show that his treadmill is inclined. The cars don't go there "on their own". They are rolling "down the hill". The thing is inclined, with a barrier at the front and the back.

  • s a
    s a

    lol, physics prof has never been sailing. Easy $10,000

  • RV12 Adventure flying G. Rose
    RV12 Adventure flying G. Rose

    This was a great experiment and I can't wait to see the one minute challenges! Fantastic!! and Congratulations to all the people in the video for their input!!

  • CadetSparklez
    CadetSparklez

    wouldnt it serve as a flywheel storing charge

    • FlyNAA
      FlyNAA

      No because the only way for it to give back the charge after storing it would be to slow down, which it doesn't.

    • CadetSparklez
      CadetSparklez

      on to next video yo find simple answer..

  • Ray
    Ray

    They just described the Bernoulli principle in about 40 different ways XD

    • Are You Going To Do The 'Ora Ora' Thing?
      Are You Going To Do The 'Ora Ora' Thing?

      lmaoooo exactly

  • Al
    Al

    And curveballs don't really curve... (sarc)