The Forces on an Airplane

How do airplanes fly? It's not magic. Learn about the forces that help (and hinder) airplane flight.
License: Creative Commons BY-NC-SA
More information at k12videos.mit.e...

[@PuffDaddyReef]

Awesome Video! I watched it with my fish.

[@ethangorodetsky6049]

Are you lonley

[@rsxzy]

it do be dead now

[@ethangorodetsky6049]

@@rsxzy oof

[@rsxzy]

@@ethangorodetsky6049 💀🤷‍♀️

[@kiwi787]

@@rsxzy hhhhhhh

[@lovehearts450]

Thank you so much for simplifying this concept. I've been stuck so long but no longer. You're a life saver!

[@elliotjones4379]

This helped me a lot, defiantly getting saved to favourites!

[@MITK12Videos]

Good question, COOLMAN0125. In this video, our equations are solving for the lift per unit wing area and drag per unit wing area. Those are what we call those "L" and "D." These are both in units of N/m^2. If you wanted to calculate the absolute lift or drag for an airplane, then you'd need to know the surface area. The equations then become: L' = 1/2 * rho * C_L * S * v^2 and D' = 1/2 * rho * C_L * S * v^2 (answer continued below)

[@mohamedalasnag8996]

So simple and to the point ... great job guys .. keep it coming :)

[@jacoballgaier2151]

Where did you get that model of the airplane

[@md83ar]

The aircraft model it appears at the beginning of the video is a Boeing 777 (cough, cough).

[@Mudux]

wow, you can read, that's impressive

[@md83ar]

Yeah, I've nothing with the 777. I find it to be a very beautiful aircraft together with the 787, as well as you. But with regards to the exterior design, I prefer the 747-400 rather than the 747-8i, although I suppose the latter is more fuel-efficient.

[@simplysimulation6570]

@@md83ar a320 gang sorry i know im 5 years late

[@MITK12Videos]

(answer continued) where S is the surface area of the wings. In these equations, L' and D' have the units of N. Relating these equations to the ones in the video, we have that L = L' / S and D = D' / S. L' and D'.

[@magreyfarhan7122]

The awesome part was about the propeller..."yeah that little guy" 🤣.. Thanks for such an awesome video

[@adrianchivas2014]

MIT is awesome...

[@jaakko132]

I study Structural Engineering and it's completely pointless using that value of g for the shear purpose of explaining the fundamentals of Aerodynamics to those who are just interested in knowing how a plane flies. It's not a lecture teaching students , including such details would just confuse the interested viewer and be a complete waste of time. I found the video fantastic and found the jokes great. Especially the disappointed astronaut ;) Well done guys!

[@reinyeradoriuq2733]

Things to take note here. Angle of attack is not the angle between the horizontal plane (wind direction) and the nose but rather the angle between the horizontal plane (wind direction) and the chord of the wing itself.

[@ChrisZoomER]

I like how the airplane model you used was of a 777-300ER.

[@chrismachabee3128]

Brilliant. absolutely genius. I knew nothing when I watched and now I understand everything. brilliant. Thank you. Seriously.

[@bgnyc1]

in math there are times where it is actually really helpful to talk about approximations, like when discussing Pi and the hypotenuse of a right angle with 2 sides of 1. But this is not such a case.

[@vaikunthdempo4610]

Awesome one guys.. keep it up :D

[@JosephDowski]

Thanks for the great vid ! Perfect for my daughter's science project. :)

[@chicagolandable]

Big thumbs up for this video...well laid out...use of humor helps immensely....and being thoughtful enough not to include background music which is pretty much always an attention breaker.... KEEP MAKING MORE VIDEOS LIKE THIS👌👌👌👍👍👍

[@itsikcarmona9845]

Flat Earth science makes the airplane flying . Hahah.

[@ilkeyigiter]

Thanks for the video. It was nostalgically hilarious and thought me a lot :)

[@hunterfagan6272]

The angle of attack is actually the angle of the chord line and relative wind

[@HDDigi]

Really awesome!

[@ft6024]

Love this explanation. Thanks guys!!! Do you have any other aviation material?

[@camilahelenferreira8409]

Hello. I just did a translation of this subtitle from english to portuguese.... Could you please authorize it to publication?

[@Kuwaiti1990]

the angle of attack is based on the chord line of the wing relative to the wind not the aircraft nose.

[@TheGuywithnolife]

You guys are funny

[@coconuts623]

Actually in America, its typically referred to as "Airplane" keep in mind that different countries have different standards that are taught by schools.

[@berndklumpp7790]

cool stuff, like!

[@andreizadasilvapereira5312]

0:11 Boeing 777-300ER 1:200 scale mockup

[@bernaferrari]

the sound quality is very bad. Too much noisy, but the video is amazing

[@Observ45er]

You got the angle of attack wrong. It is to the wing, not the nose. There is a difference due to the angle of incidence of the wing to the fuselage..

[@michael.1101]

really cool way of explaining :)

[@NH-en6et]

Awesome video! I like that you guys explain the equation for lift and drag. Thanks a bunch! I created a wooden glider for physics and needed some information for my written report. You guys helped!

[@evilzkun8284]

L=(1/2)*(rho)*(V^2)*(Cl)*S S or Surafce Area is missing in the video

[@mjada76]

Surface area changes with the angle of attack as was explained in the video.

[@StrsAmbrg]

That should have to be explained that the surface area wide is changed depend on situation: (when take off or landing).

[@AchiragChiragg]

He did mention magnitude of lift "per unit area"

[@AmbientMorality]

@@mjada76 surface area does not change with angle of attack

[@VelhaGuardaTricolor]

1:40 has nothing to do with SIZE but MASS and NO they are not the same thing due to different densities. For instance, a planet the size of the Moon but made out of LEAD would have a way bigger gravitational pull than JUPITER Capice?

[@DarkCeremony]

What about induced drag? Why is induced drag (1/2)* rho * S * v^2 *(C_L^2/(pi* aspect_ratio)) not included?

[@Doriesep6622]

So the laws of aerodynamics are not just flimsy superstitions. There is a method to all. It is figurable-outable. What happens to a plane in the air is not willy nilly. Thank you. English teacher here.

[@zayedalsuwaidi7697]

Is Weight the correct term or is it gravity?

[@haiya123456789]

it's weight don't ask me how

[@zayedalsuwaidi7697]

Que Naim thanks m8

[@mjada76]

Don't qoute me here, but the only thing I could think of is that weight which is the sum of mass X gravity being used because it affects thrust and lift. Another thing the airplane is not in free fall so other forces will have to be taken into consideration.

[@raahimhadi4905]

It's MIT. Don't question it.

[@AmbientMorality]

@@zayedalsuwaidi7697 Weight is the force due to gravity

[@robertmarks6525]

thank you sir 👍

[@yourmeede]

the handclap killed me lmfao

[@MAMotinSobujsobuj23]

Tanks a lot. I got the real idea about the aircraft flying.

[@How1105]

I'd love a model of the 787!!

[@How1105]

***** Sorry, spelling mistake. I hit 8 by accident.

[@michaeladi8847]

+GlitchedGaming 1087 it's a 777-300ER though

[@ReadingThis1]

interesting info... facts..... explained well....

[@MrRaT3D10]

How do these big object take off tho?

[@puffcatco]

science but its very easy. wings and rotor makes it goes up

[@COOLMAN0125]

What about the surface area of the wing? Shouldn't it be in formula?

[@OT7_Tae]

What forces are equal when the airplane is on rest?

[@royalfuzion9426]

I know stall its when your plane drops speed and height right?

[@NikkexD]

Really good stuff

[@TheBeetrootman]

Well I Learn a few things. Mainly just the roe thing.

[@parkerdial]

Really good and funny!

[@emelyhernandez6571]

I need to cite this but I don't see any information on it

[@selenalamothe997]

making learning funny, thank you!!

[@sunku260]

thanks a lot

[@thehunter3290]

This helped me with my homework

[@leonardozhou7844]

1:16 from the center of the object

[@AnDPineapple]

this made me giggle. great video :)

[@SanthoshKumar-bm9kh]

are the forces equal in magnitude and opposite in direction ?

[@alialwani2413]

offcourse not if they were then the airplane will be in equilibrium and it will not move neither vertically nor horizontally

[@AmbientMorality]

@@alialwani2413 False, in steady level unaccelerated flight (like cruising) the forces are in equilibrium. Velocity doesn't matter; if the acceleration is zero then the forces must be

[@rahj1365]

Good Job!

[@dalyinnz]

Nice Video Folks - well done!

[@Yeiyn343]

Great video! :)

[@concorde9433]

I agree

[@bruno13almeida]

Nice! now I'll build one airplane hahah thanks so much!

[@xXEpicMehXx]

I remember getting a model 777-200 when I was 6. Broke it instantly and had to mess it up by plopping glue all over it. Yay.

[@FedericonpFer]

nice..

[@yulianussituru4872]

I want those B777 miniature..

[@paul1964uk]

0:12 No, it's an "aeroplane". We could agree to call it an aircraft though.

[@aayushsachdev5352]

Nice

[@appletree8441]

left to right with the plane model would have looked better, and worked better with the graphs. next... float,flutter, fly, glide, fall.

[@muratkar8753]

what happened to areas in formulas ?

[@jadenbezzel212]

Is that 1:200 or 1:400 that hogan 777-200

[@BenLewisE]

Sorry, I guess I was being very picky. I still think though that he should have pointed out that it was an approximation...

[@swilsonmc2]

has anyone ever seen a video of an astronaut jumping really high on the moon? 1/6 gravity should mean 6x higher, right?

[@AchiragChiragg]

It's not that straight forward.

[@Hugh.Manatee]

Only on your side of the pond mate! ;)

[@SpeedyWinds]

This ROCK!

[@jhonatanmduarte]

Fantástico!

[@chiliogpepperoni]

Dat astronaut though.

[@2755_Ishycakes]

Wouldn't D' = 1/2 * rho * C_L * S * v^2 be calculated with coefficient of drag (C_D), though, and not C_L? Not entirely sure, because I guess lift can have an impact on drag (induced drag) etc...

[@MrShapronForU]

cool vid :D

[@manivannan2020]

Gg hello

[@Hugh.Manatee]

You do realise the force of gravity is not equal on all points of the earth right? The fact that the earth is not a sphere, but an oblong alone creates of variance of .5% between the poles and the equator. Your number 9.81 holds true on most places on the earth surface, whereas 9.80665... I'm guessing you got that number from an experiment you did for school? Try the same experiment on a ship in the middle of the Atlantic around the equator and you'll get a completely different number.

[@mossmoss2019]

ypu got me at the fairy one. subscirbed!

[@BenLewisE]

@MITK12Videos This is not good. You say things that are wrong without even explaining you inaccuracies or simplifications. g does not equal 9.81, standard gravity is 9.80665, but even this is an approximation. The forces themselves are simplifications since there are many hundreds of different forces acting on different parts of the plane, but again, these work out to leave us with what you described... (I am studying AS in the UK atm, but was interested to see what you were making :P )

[@Henoik]

"So this is an airplane here"... Cool. Why didn't you mention it was a B777? I saw it at once.

[@chiliogpepperoni]

Wow, you knew the whole time it was science but didn't tell the elves and wizards working hard all day, risking their lives just to carry another plane to it's destination. Lots of lives were lost. Both elves and wizards, and even humans, and they took the blame.

[@latropajaleosa]

see veritasium's explanation, it complements this one a bit. Still not perfect

[@avia3089]

is not pressure drag is parasite drag

[@SuperVada]

In other words, Homelander couldn't save them

[@techkiller24]

Our teacher showed this in our class

[@gary12xxx]

haha those scientists, they look so happy.

[@mlccrl]

When explaining why planes fly please don't forget the necessity of a pilot. No pilot no fly. (questa battuta del c..o dovrebbe far sbellicare gli americani)

[@David-du3si]

true lol

[@MrVeenty]

science = cool magic

[@sameersameerulla1460]

I Airplane drawing

[@latropajaleosa]

... it still does not explain why airplanes fly.... so it left us waiting for the important part... still a good try.

[@thomasgandalf4111]

actually it's physics or law of nature, last time I checked

[@thadream_13_10]

who does theses videos

[@shivshankarpe]

ThaRunna3D Its some sort of a collaboration between MIT and Khan Academy. Or, that's what I think based on this video: watch?v=VA273i3z7Mk.

[@pilot001945]

Wrong expl. angle of attack

[@andreaslazarou4821]

Hey. Its good!!!!¿

[@Observ45er]

Goofy video from MIT. Not what you'd expect......Dissaperium Leviosa !

[@Arramah]

you missed the wing area

[@laxide13]

lol funny way of learning

[@velvetjuzzy]

can i work for nasa now