Physics 68 Lagrangian Mechanics (1 of 25) What is Lagrangian Mechanics?

[@cjlooklin1914]

Wow, this guy saved during undergraduate physics. After the class I forgot all about him. Years later I'm dying in my graduate level robotics class and here he is saving me again. You sir are a real hero/educator!

[@MrRObot-bin]

Same here, electromechanical engineering in Mexico this videos are pure GOLD

[@JimmyGray]

Best description of the Lagrangian I've been able to get thus far in my years of study so thank you:)

[@gametime3473]

holy crap. i went through so many textbooks trying to understand what a lagrangian is. the only thing i did was get more confused. but this angel explained in way that makes a lagrangian seem obvious.

[@MichelvanBiezen]

we thank you!

[@annashrtanjungpridasiwi758]

I wish in this world there are more people like you. You are smart, have a good attitude, humble and kind. Thankyou so much

[@Phyzzics_ch]

You’re just… perfect.. I don’t know other words to describe you.. someone should create a word just to define the way you help to understand those arguments. Just a tip, he’s Italian, his real name was GIUSEPPE LAGRANGIA, he changed it to sound more “aristocratic” when he moved in France I think.. love you thanks for everything

[@MichelvanBiezen]

I am far from perfect. 🙂

[@Phyzzics_ch]

@@MichelvanBiezen We all agree that these are topics that have a certain level of complexity. It is not always easy to understand them right away. Whether it's the Lagrangian, whether it's physics or Mathematics, at the end of each of your videos every topic becomes clear and what remains is a linear thought about it. The purpose of teaching is to make people understand, you achieve that purpose as very few professors know how to do. It's perfect. Thanks a lot. Really. Maybe you don't often think about the turn of what you do, you save people’s time and you make us realize that even the most difficult things can be understood (also increase our self-esteem😅) thanks again 🌺

[@jaeyeonkim7656]

Your explanation is just as simple and powerful as Lagrangian! Thank you so much! ;)

[@MichelvanBiezen]

You're very welcome!

[@ghasthordegd1201]

@@MichelvanBiezen can you do videos on the standard model lagrange

[@evantkchong]

Thank you so much for your videos, as a physics undergraduate they're really helpful!

[@ernestjesly]

Most talented person slows his speed to raise many talented persons. You are blessed.

[@MichelvanBiezen]

Thank you. Glad you like our videos.

[@joewebster903]

The best explanation I have seen I wish he was my physics teacher in the past

[@beoptimistic5853]

https: //kzbin.info/www/bejne/i3nSlHp-nNqKgKs👍

[@scwu9672]

Finally Lagrangian mechanics makes some sense to me. Thanks for the illustration of video!

[@f3ynman44]

My mind exploded at 6:10! Awesome explanations - What a great teacher!

[@Peter_1986]

These videos are exactly what I have been looking for about Lagrangian Mechanics. For some reason most other videos are obsessed with "Lagrange Multipliers", and they don't look anything like the examples in these videos, where you are actually supposed to use the formula L = T - V.

[@larrybryant4827]

These videos are a treasure! Thank you for putting these together.

[@pelimies1818]

Gotcha! I'm off to bar to impress the ladies!

[@PAOLOBOZZ]

As clear as it can get! Thanks so much!

[@jhkbgyffbnkyugny]

I've been clearly going to wrong bars :D

[@greg77389]

"Hey baby, I know how to derive a = -g using the Lagrangian"

[@darkseid856]

@@greg77389 😂👌

[@nayy0001]

greg77389 Girl: “How about you put that d/dt back in your pants?”

[@brendanward2991]

The perfect introduction to Lagrangian Mechanics. Thank you.

[@ameenullah6599]

I understand your lecture more easily than any other teaching me in boring classes thank you soooooo much

[@mrbigcat9]

Joseph-Louis Lagrange[a] (born Giuseppe Luigi Lagrangia or Giuseppe Ludovico De la Grange Tournier; January 1736 - 10 April 1813), also reported as Giuseppe Luigi Lagrange or Lagrangia, was an Italian mathematician and astronomer, later naturalized French. He made significant contributions to the fields of analysis, number theory, and both classical and celestial mechanics.

[@theasteroid00]

Thank you for your videos; your calculus 2 lectures helped me so much in getting through that class (which is known as a gpa killer at my uni, something i was unaware of when I signed up for it as a freshman). Now I'm in my third year as a physics major and I'm greatful that i can make use of your videos once again!

[@MichelvanBiezen]

Keep it going. Glad we can be of help.

[@ethan_martin]

I am so hyped to see the rest of your videos. I learned how to derive the euler lagrange equation a few days ago and seeing these examples in physics blow my mind :P

[@JH-ux1re]

Wow! Lagrange is a genius! This video convinces me that Lagrangian formula is so true! Thank you so much!

[@MichelvanBiezen]

Yes, he had an incredible talent thinking these concepts through. "The principle of least action" is another one of his concepts that is brilliant. (we have videos on that as well)

[@xtremedude1526]

This is excellent. Extremely clear and precise. You must be a great teacher.

[@b1ackwollf]

this teacher is hands down the best in explanation

[@MichelvanBiezen]

Thank you. Glad you like our videos. 🙂

[@b1ackwollf]

@@MichelvanBiezen thank you sir, i will follow your channel for my msc physics course doubts and concept clearing. I urge you to provide the stat mech and quantum mech videos as well

[@fakherhalim]

Very clear explanation, perhaps the best I have seen so far!

[@eraniklihsuk]

Thank you professor. You have made it easy to understand the topic.

[@LowellBoggs]

Oh thank you for carefully explaining this subject in a step by step fashion using both a simple case, which is intuitive to under stand the math behind, and not using some counter intuitive coordinate scheme. I have watched several videos on this and this quickly because of strange coordinate choices and overly complicated examples.

[@MichelvanBiezen]

Glad it was helpful!

[@roychan3929]

Very good video! Clear and easy to understand! Thanks for helping to increase the knowledge of the world!

[@amiraaissiou8426]

This video series is great. You are great. Thank you so much. plz lead our nation.

[@herohero-fw1vc]

Very important in identifying the frame of reference.....most people ignore the most fundamental thing for being too obvious.

[@adityaagarwalla4126]

Excellent work sir... It helped me a lot a night before my semester...

[@mnada72]

Thank you , the explanation is clear and to the point , I had never heard of Lagrange during my study period and brought to here under the influence of wanting to understand another video. but I am very happy to find your channel on my way , It will open a new horizons for me

[@wyattdavidson5003]

You my friend, are a life-saver………thank you for all you do.

[@MichelvanBiezen]

Glad the videos are helpful

[@massimoazzano]

Lagrangia was a italian from Torino. In the last period of his life ,at age 51, he moved from Berlin to Paris to teach. France changed his surname.

[@MichelvanBiezen]

Great information. Thanks.

[@arunbhaskarkaranayilanil6677]

Thank you sir for this lecture. Our professor was giving us a hard time for this topic. Surely you made it easy..

[@MichelvanBiezen]

Glad you found our videos.

[@Joys_Gellert]

My God! At least I understood the basics of Lagrange mech. Thank you!

[@qwerty14142]

Excellent explanation, I am eternally grateful.

[@yanemailg]

Your lagrange pronunciation is correct. Thank you for the video.

[@bangscutter]

Often in physics courses, Lagrangian mechanics is taught by starting with deriving how it all came about in the first place (the principle of least work). That is overwhelming for most people to be hit with all those proofs at once. This approach is much better, by starting with a practical way of how to actually use Lagrangian mechanics in a simple scenario. The derivation of the principle of least work can come later.

[@madansharma2700]

Your comments are accurate and good.

[@beoptimistic5853]

https: //kzbin.info/www/bejne/i3nSlHp-nNqKgKs👍

[@biswajitbehera6782]

Thanks you so much Sir ❤️🙏🙌 Love from Odisha, India 🇮🇳❤️💫

[@MichelvanBiezen]

Welcome to the channel!

[@arachan5280]

Thank you so much this is very helpful , you are more useful than my teacher

[@viviennoble5791]

Thank you so much for this fantastic introduction to Lagrangian Mechanics - your explanations are first class!

[@MichelvanBiezen]

Glad you found us. And thank you for the comment.

[@PETERTRITSCH]

The first time I understand something about Lagrangian mechanics

[@MichelvanBiezen]

Great! Glad you found our videos. 🙂

[@sanchitaagte8215]

sir you're a lifesaver!!!! could not appreciate you enough. god's work

[@klam77]

Hello again, professor! I am back to this great series after watching the movie "Arrival" (an OK-ish movie), but more importantly, the movie led me to read the short story on which it's based (at only 50 pages, but SO MUCH more to say than the movie, typical!). And....the crux of short story (by Ted Chiang) was that the aliens base their physics on different fundamental phenomena than we humans do. We humans see things in time, causally. This causes us to focus on "stock variables" (those measured AT particular instants) like position, energy etc. Whereas the aliens focus on "flow variables" as the first instance investigation of nature (ie those vars occurring OVER an interval). And from accounting (!) (and, btw, common sense) we know, the rate of change of stock variables = flow variables.And Chiang's short story goes on to mention that the aliens base their physics on variational principles like Lagrange etc. So i was trying to come back and see if there was an interpretation to be had of Lagrange's formula in terms of concepts of "stock" and "flow". A very interesting line of thought! It seems like if you take the left hand side of the "L" differential equation and set it EQUAL to the partial deriv of "L" wrt "X" (rather than subtracting it and setting = 0) then you can set up some type of stock-flow paradigm: (From left to right) The rate of change of potential energy "stock" TO kinetic energy "stock" is equal to the (and this last bit is a bit conceptually dodgy for me still...) "flow" of "L" (ie. gradient) over space (really just the one-dimensional "x"). You think this makes sense, eh? It's a fun line of thought! Broached by former science major and writer Ted chiang! Kind of worth mulling over eh?

[@susithgamage3567]

The best explanation I have ever seen. Thank you so much ❤

[@x7Degreesx]

Very well put and most importantly straight to the point. You are a true proffessor. Thank you so much

[@williammchargue6120]

Phenomenal video! Very clear and very well done. Thank you for your passion and your knowledge!

[@joelarpin473]

Wow. My first time here. Super impressed with your teaching skills.

[@MichelvanBiezen]

Glad you found us. Welcome to the channel!

[@s3xydutchm4n13]

This is so much clearer and a great way to enter this subject. Now I can actually understand what my professor is saying. LOL

[@bigrover5435]

Clearest explanation I've found !!!

[@MichelvanBiezen]

Glad it was helpful!

[@hitesharya8213]

such a great teacher u r ,sir,,I salute u,,u made everything clear,,, keep it up,, God bless u

[@najishaban8052]

Nice video, but I have a simple question: Immediately after minute 3:45, where he took the partial derivative of kinetic energy with respect to x he made it zero since there is no x term, but couldn't x dot (velocity) be a function of x? For example of the speed was position dependent (e.g. position was x square) then its derivative (velocity) would contain x term (e.x. x square would give a velocity of 2x). This means that the derivative of kinetic energy with respect to x is not necessarily zero!! Any explanations?

[@marcossidoruk8033]

Yes, totally, the video Is wrong.

[@marcossidoruk8033]

@IronPump89 yes exactly.

[@nguyentranvan5115]

This is a common point of confusion when one gets started in Lagrangian mechanics. The important thing to notice is that we are taking partial derivatives, not full derivatives with respect to x. From the point of view of our partial derivatives, x and x dot˙ are completely separate variables with no relation to each other. To give you a bit of intuition as to why this must be the case, consider a free particle in space (ie. no potential energy), no other particles to interact with. Should it's kinetic energy depend on where it is in this space? No! So the derivative of the kinetic energy with respect to the position must vanish. Answered by Mason from Physics stack exchange

[@muckrakerwm.8498]

Thanks V.B. for these great videos to help one better understand the Lagrangian. I salute your altruism.

[@ashimdhakal170]

One of the best 9 minutes of my life 😍

[@Debjit625]

I am never disappointed with your lectures,always the best

[@PKsuefaPK]

This channel should be simply named 'Genius'.

[@pmluciano]

Amazing videos!! I hadn't understand anything till now. Thank you so much for making this kind of videos

[@wilts8965]

The people who said this is the best explanation of the lagrangian are not exaggerating

[@shrishpatil9978]

Really an underrated yt channel.

[@feynstein1004]

I was waiting for him to say the The Lagrangian is also known as "action" and hopefully talk about the principle of least action. Perhaps in a future video.

[@prashantlale4976]

Mr. Michel thanks for making this video this was really good to understand in such simple way

[@MichelvanBiezen]

Glad it was helpful!

[@eriknelson2559]

Minimizing (the integral of) L=T-V "tries to make" (on average) L=0 or T=V, which is equipartition of energy in Statistical Mechanics. Exactly true for SHO and virtually every potential is quadratic about equilibrium.

[@sufalmanorath]

Good lecture. Thanks for being crystal clear and quick.

[@ajithnandakumar8244]

Really clear and fantastic teaching..

[@matiassantacruz5487]

Sir, you have single-handedly saved me!!! I LOVE you!

[@MichelvanBiezen]

That is great to see. Thanks for the feedback.

[@albertoolmos21]

This is just an example of the Euler-Lagrange equation working in classical mechanics. The beauty comes, however, from its derivation, which is responding to the question “how infinitesimal position changes of a particle result in a minimal, near zero, energy change”. Solving this is not obvious because it depends, among other calculus-related operations, on the position itself, the speed, and the acceleration. The Euler-Lagrange equation can respond to the general universal question (since primary school) “what is the shortest path between two points”.

[@surendrakverma555]

Very good lecture Sir. Thanks and Regards 🙏🙏🙏🙏😊😊

[@MichelvanBiezen]

Glad you liked it.

[@albertyeung5787]

good attempt to talk about Lagrangian Mechanics

[@MichelvanBiezen]

Glad you liked it. 🙂

[@aryanrockinggaming6950]

real educator

[@davidrandell2224]

D=1/2at^2. Galilean relative motion has the earth approaching the released object. No energy: not kinetic, mechanical, solar, potential or endless suppositions. The Atomic Expansion Equation eliminates all this confusion. “The Final Theory: Rethinking Our Scientific Legacy “, Mark McCutcheon.

[@RahmanIITDelhi]

awesome explanation of lagrangian via a very simple classical manner.

[@tdh5121994]

please complete the series this is too helpful

[@58capricorn82]

His teaching is super cool... 😎

[@MichelvanBiezen]

Thank you. Glad you like it. Pass the word. 🙂

[@foreverofthestars4718]

I love the videos. The only thing I'd recommend is working on audio quality.

[@Citius1974]

Crystal clear explanation...thanks!

[@mazzarri00]

Thank you so much mr. Van Biezen... only a curiosity: LAGRANGE was born in my town, Torino (Italy) . he has originally the italian name La Grangia of his father... but when he was more or less 18 he was sent to Paris in order to study science and he became french

[@rodrigomartinorduna7408]

I'm 15 and was able to understand it. Thanks m8

[@MichelvanBiezen]

Very good!

[@kr4bz]

I think I'm a bit confused, when you derive the Lagrangian in terms of x, you say that the first term does not have an x and therefor becomes null, but doesn't it contain an x? My understanding is that x_dot = d(x)/dt? Can you factor it out when when deriving in terms of x? Example d/dx(dx/dt) = d/dt?

[@kr4bz]

@Hamish Blair I saw from a website they did cancel each other out, so basically, d/dx(dx/dt) = d/dt(dx/dx) = d/dt(1)=0. But thanks for the reply :)

[@lolitachkhaidze1534]

How is x-dot not function of x?I mean if we have x=2t^2 that means that x-dot=velocity=4t so it changes due time so changes with respect to x. To make clear I say that in different positions velocity is different so it is depends on x coordinate

[@grandimadhav7965]

@@lolitachkhaidze1534 its partial differentiation. As long as no relation been provided it must be treated as an independent variable.

[@syedabid7823]

Really great explanation sir

[@ahmadyar66]

What a guy. Keep going SIR

[@MichelvanBiezen]

Thank you. That is the plan. 🙂

[@dihan6130]

I love the cello on the bottom right corner!

[@dilsad6789]

Thank you for the clear explanation, really liked it!

[@MichelvanBiezen]

You're very welcome!

[@m.asyfa.95]

3:10 I think it will be easier if we use y and y-dot for position and velocity respectively, instead of x and x-dot.

[@ReidarWasenius]

THANK YOU for a very clear description!

[@Explore_With_Sagar]

Love you sir.....a best description

[@subhankarmishra5422]

You are next to God for me....Thanks a lo.....

[@husamwadi2635]

Thank you Michel. You are a great person.

[@MichelvanBiezen]

Far from it, but glad that the videos are helping.

[@duegia44]

Why's a = -9.81 though? If the object's falling down, acceleration have the same direction as g which is down then should it be positive?

[@vinitchauhan2928]

in free fall is all about reference frame gravity is negative since is traveling in the negative Direction and acceleration is is a vector, we assume it's negative if the ground is the reference position.

[@maybebrilliantthoughts9884]

Thank you very mach for this video! I'm from Ukraine, so english is not my native language, but I understand all the video

[@MichelvanBiezen]

Welcome to the channel!

[@duckymomo7935]

Lagrangian here is overkill but using a simple example is perfect

[@MichelvanBiezen]

Yes, it was a good way to explain what it actually is.

[@cleisonmanriqueaguirre8184]

thank you for the video and actually knowed my questions in the end of the video

[@MichelvanBiezen]

Glad it helped.

[@Warriorpend2]

Shouldn't the Lagrange-Euler equation be DL/Dx - (d/dt)[DL/Dx']? I guess it doesn't matter, since you can factor out a negative 1 and then divide both sides, right?

[@vinitchauhan2928]

Yes but in he wrote it such that F=ma not F-ma=0 but it doesn't matter using basic arithmetic.

[@newmanhiding2314]

Does this not assume that x and x’ are completely independent of each other? Otherwise you would not be able to treat them like constants in the partial derivatives

[@MichelvanBiezen]

They don't have to be independent of one another. Taking the partial derivative simply calculated how the function is affected by changing one variable while holding the other constant. (It doesn't mean that the other variable is constant)

[@MichelvanBiezen]

We do have videos on partial derivatives in the calculus section

[@newmanhiding2314]

@@MichelvanBiezen Thank you!

[@alejandraacosta248]

You explain so clearly! Thanks!

[@MichelvanBiezen]

Thank you. Glad you find the videos helpful. 🙂

[@sarafattack3188]

you have saved me so much time trying to get my head around things, thank you so much!

[@MichelvanBiezen]

Happy to help!

[@jim2376]

Outstanding teacher.

[@MichelvanBiezen]

Thank you! 😃

[@tzaidi2349]

Great example. Great teaching. Great bowtie. Thanks!

[@amritaashwini]

if you can do any lecture on the jordan-brouwer separation theorem for smooth hypersurfaces

[@larrynicholas9730]

I wish my Physics Professor had explained as well as you.

[@MichelvanBiezen]

Thank you for the affirmation.

[@Anthony1102www]

@ Michel van Biezen is it possible that you can create more videos of the Lagrange Mechanics? such of the center of mass frame, Hamiton principle or the effective potential something like that

[@MichelvanBiezen]

It is part of our plan, but time is out biggest enemy as we are trying to cover many topics.

[@Anthony1102www]

​@@MichelvanBiezen OMG you know what I tried to send a message to you in FB XD, so glad you reply in here.!!! Anyway looking forward to viewing those topic become true!! thank you so much Sir!!

[@hitesharya8213]

such a great teacher u r ,sir