15. Introduction to Lagrange With Examples
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- čas přidán 2. 09. 2013
- MIT 2.003SC Engineering Dynamics, Fall 2011
View the complete course: ocw.mit.edu/2-003SCF11
Instructor: J. Kim Vandiver
License: Creative Commons BY-NC-SA
More information at ocw.mit.edu/terms
More courses at ocw.mit.edu
Love how he takes his time to write. It is underrated. When profs write, students get a chance to think, write, process what's being introduced.
I noticed that as well.
Indeed! And for students with profs whose first language is not English, it really helps until the student's ear acclimates to the prof's accent if he/she is difficult to understand.
I agree with your 100%
It’s not possible to like this comment enough.
@@markproulx1472 : Thank you for understanding the implication of writing as I've experienced it. Perhaps your experience is similar too? :-)
I'm studying mechanical engineering in Italy, our professor's introduced the Lagrange equations to us making tons of calculations and partial derivatives without even explaining the sense of what he was doing. This, however, is by far the clearest explanation I've found about this fascinating topic, I wish I would have had a professor like him teaching my courses.
exactly. I'm from Pakistan, a country that is much father than even Italy. all we did is become better calculators. never learned when these concepts will come to use or even what the equations mean, how we can use them.
@@AhmadNavidHazara i can understand bro, same is in India.... Best of luck
me too
Posso chiederti dove studi?
well now you do, you just needed to find him here on youtube!
I really appreciate the open courses from MIT. They honestly saved my life. Much more intuition instead of plain math formula are taught in the videos than in the lectures from my college.
Plz solve one paper for me I sent you
This is the most insightful and detailed lecture on Lagrangian Mechanics out there. Thanks J. Kim Vandiver. Your problem solving approach is so stimulating and engaging!
This is the most detailed explanation of Lagrange EOM I have found on the net so far! Thank you much!
really? i can't believed, he didn't even explain where "L=T-V" comes from.
Do you have more detailed course on analytic mechanics?
czcams.com/play/PL69875B9976A7E737.html
@@lauraesthela6941
I personally think that lectures should be spent more on example problems instead of rigorous proofs and derivations.
The lectures are primarily supposed to be a foundation for your studies anyway, they aren't supposed to cover the material that the course books already talk about at length.
I also think that proofs make much more sense after you have already tried a few example problems - they shouldn't be this mysterious mess of symbols and definitions, they should actually mean something and become obvious to you after you have checked them a couple times, otherwise they are useless.
@@Peter_1986 WELL SAID
Genuine interest of a brilliant engineer for teaching. The best explanation of the Lagrange equation showing the way to solve hard problems. Now I know MIT’s reputation.
I love your site, and intend to study all of your math, chemistry, materials sciences, and physics courses. Thank you. I love the texts and homework sets!
Professor Vandiver, thank you for an incredible lecture on the Introduction to Lagrange Equations with detailed Examples. This lecture really explained Lagrange Equations in full detail.
Lies again? Eat Drink
Thank u so much for sharing this lecture with the world! Recently we reviewed this content in clases but I didn't get it quite good. Now I definitely understand it way better!!!
his voice is so relaxing
this is the nicest professor ever!
Great explanation. Clear and simple. Good job Prof. Vandiver
Ugh I love this stuff... I should probably go to grad school for me or robotics. Feeing nostalgia big time right now. Thank you mit.
The best I've come across so far. !!
just wow. goes to show how different universities can be. i went to school for applied math with a concentration in stats, so i ended up having to taking a lot of physics classes because those met a lot of my pre-reqs for my degree. and not once in any of my upper division physics classes, did the prof ever mention how you need to test first to see if you can use a lagrangian. apparently they just always gave us problems where it worked, and they just left that entire part out.
As usual institutions like MIT gets the best professors to go with there top line students, so success is almost guaranteed! My professor never came close to explaining the Lagrangian like this professor.
Thanks a lot for this Sir. The way you gradually explain and write makes understanding very easy.
This is great lecture if u wanna visualise and reason... And do things systematically... Greatful to the lecturer and the organisation to make it available to the world...
VAIBHAV DlXIT
Yes!! 🇺🇸MIT!!
Beautiful lecture!....and beautiful the fact that you can play it a 1.5x speed!
Thanks. 1.5x saved a lot of time
i watched it in 2x speed
Just started this topic on my vibrations class and this is a life saver
I had the happy opportunity to have a great math teacher already at the age of 9. And his classes were fundamental to me until the master's degree, already 27 years old. Congratulations to all the great masters of mathematics. BRAZIL BRASÍLIA
Wonderful lecture and incredible instructor!
I know nothing about engineering, but I know a good professor when I see one. As a professor myself, I'm always trying to get better at my craft.
We would like to inform you that the video czcams.com/video/LIzqmOv2lHc/video.html
has been uploaded on my channel. Please have a look.
I'm studying physics in Salamanca, Spain, and this video was really useful
Thank you for them!
I'm stydy in moroco you kan help me or i 'have idee pour continu ma stayding in spain
I am a Mechanical Engineer and this is far one of the best class!
waw.....after leaving university for almost 10 years. This is so cool!!
So much better and more efficient than my lecturer, thanks :)
At 52:00, there should also be a term for gravitational potential energy (PE) of sleeve due to rotation of the rod. The gravitational PE of the sleeve due to stretching is taken into account, but not due to angular motion of the sleeve.
This professor is GREAT. I am impressed. Thanks!
Thankyou. Professor.
I am an engineer and am watching that for fun instead of doing my work... I am a sick man.
"In 1766, on the recommendation of Swiss Leonhard Euler and French d'Alembert, Lagrange succeeded Euler as the director of mathematics at the Prussian Academy of Sciences in Berlin, Prussia, where he stayed for over twenty years, producing volumes of work and winning several prizes of the French Academy of Sciences. Lagrange's treatise on analytical mechanics (Mécanique analytique, 4. ed., 2 vols. Paris: Gauthier-Villars et fils, 1788-89), written in Berlin and first published in 1788, offered the most comprehensive treatment of classical mechanics since Newton and formed a basis for the development of mathematical physics in the nineteenth century.
In 1787, at age 51, he moved from Berlin to Paris and became a member of the French Academy of Sciences. He remained in France until the end of his life. He was instrumental in the decimalisation in Revolutionary France, became the first professor of analysis at the École Polytechnique upon its opening in 1794, was a founding member of the Bureau des Longitudes, and became Senator in 1799." Wikipedia
what a perfect professor
dat combover tho
I Z dat’s stupid of you
This explanation is wonderful.
Thank you MIT . Best technical university in the world
Thank you FRANCO FERRUCCI. I was becoming bored until I increased the speed. Now he's become a much better lecturer. Perhaps some other lectures would be more interesting with similar treatment !!!!!!!!!!!!!
شكرا جزيلا على هذا المحتوى الراقي 💜💜🤍
profesor sorry for words, you are awesome
thanks to your explanation the greatest insights of the greatest mathematicians are easy to understand
Very clear introduction. Thank you.
Holy crap that rod and sleeve problem is insane. I don't think my professor would ever expect my class to solve something like that.
This is MIT though so I don't know what I expected.
Evan Schurr It's lagrangian mechanics, all physics undergrads take it
It was pretty mean. I paused and tried it all. I got stuck on the kinetic energies of the objects actually lol. I was pretty off.
@@xFoKe In the Philippines, Langagian Mechanics and Hamiltonian Mechanics is thought in Master's Degree
Dane Gil Cabrales I’m in my second year of the theoretical physics bachalor and I’m taking classical mechanics with lagrange, hamilton and special relativity. The course is obligatory.
@@yerhing6406 what country are you studying in?
His consistently slow paced talking makes using the 1.5x or 2x speed option a great alternative.
1.25 will do
2x speed on anybody is ridiculous
@@user-en5vj6vr2u there are some nptel lectures where you need 2x speed to actually understand what professor is teaching. They speak very very slow.
Fantastic teacher!
I have a retake of the exam tommorow YOU SAVED ME ❤️
18:12 that is because the rotations are not conmutative. Furthermore, 2 rotations is just a subspace of Lie Algebra, se(3), of Euclidean Group, SE(3), to be holonomic you need the movement be a subalgebra of Lie Algebra, like 3 rotations (spherical) or general planar motion (x and y traslations y z rotation) or planar traslation etc.
The best lecture....
Great Work!!
Great course
thank you professor
super lecture.
Brilliant explanation
Excellent lecture.However, I'm in trouble understanding Hamilton's principle and Kane/Jourdain 's Principle. Is there any lecture including these content?
Step by step video solutions for civil engineering questions
와우! 칠판도 9개다 전동으로 움직이고 필요하면 내려서 보고, 따라 적고...... 이 시스템 좋다. 강의를 듣는 학생이 많은지 글자도 크게 쓰고,,,,,, MIT 가보지 않았으니.......... 지금은 바뀌었겠지
Dear sir, I love u very much!!!
حلو الشرح ومفيد ☺️
thank you for the explanation. i was following lectures from the start. I found that there may be lecture missing about how to calculate KE and PE for translating and rotating frames. you keep on referring that lecture like " as we calculated in previous lecture etc etc". will you please add that lecture or give me some reference which is more alike to your previous lecture to successfully calculate KE and PE for any system.. please help.
The conceptual descriptions here are cogent and systematic, but I think the jump from a spring pendulum to that rod/sleeve problem serves to confuse rather than make anything clearer. I understand wanting to give students a challenging problem so that others are easy by comparison, but there seems to me to be too much to keep track of in that problem-rotation, driving force etc.-to solidify the concepts by example. You lose the forest in the trees. I think a more intermediate problem might have been useful to solve to completion.
Very nice! Thank you!
According to J. L Meriam (Dynamics), which stated the Lagrange Equation based on L =T-V is valid for conservative forces only. For non conservative forces the Lagranger Equation shall modified for T (kinetic energy) not L. Please advise.
I don't know why I watched this at 1AM but I actually understood the lecture and didn't watch the previous ones :D
My physics professor at my local community college is just as good as this guy. My professor received his Ph.D. from the University of Chicago and I think is just as smart as any physics professor at MIT.
You are lucky to have a community college lecturer who seemed to be as good as one from MIT. And it is possible to have a lecturer from MIT to be worse. A place like that hires people who can obtain research funding from which a fraction of the salary comes. And the hiring process involves ONE public talk, based on which the candidate’s EQ (ability to understand the question) and IQ (cleverness of the answer to the question or the way in which the answer is delivered) are judged. Mercifully (for the students) there is a 6-12 year period of observation before a candidate receives tenure and becomes a part of the permanent staff.
I really like this lecturer
Thank you so much for this video! i´m an student for the upm (universidad politécnica de madrid), in spain. If there are any videos about hit transfer i would apreciate it.
Try going through "Elementary Applied Partial Differential Equations With Fourier Series And Boundary Value Problems" by Richard Haberman for any help in heat transfer theory. I found this book extremely helpful with explanations :)
Cool!! I will read it, thanks.
For heat transfer lectures you can use www(dot)nptel(dol)iitm(dot)ac(dot)in
I followed this through and worked the examples ... in the final collection of d(δΤ/δx)/dt terms there is a Coriolis component 2*m2*x*(dx/dt)*(dθ/dt) to which he refers (at 1:14:46). I cannot see where this was derived in the KE term at 58:00 nor thereafter. Can someone help me by telling me what I am missing?
Where does the coreolis term (2M2*X1..) comes from , in the therm 1 of lagrange equation for the theta component?
I just don't see it in the derivatives...
강의 속도가 느린 것도 아주 좋아요. 외국인을 배려한 강의인듯 하네요.
50:30.. I think the refrence of potential energy for the rod is when theta equals 90 degree, max potential energy. and zero potentional enegry when it's straight down, that's why he got confusion about the signs, so the equation is correct.
From what he said, reference position (= Equilibrium position) is when rod is vertically hanging from the pin. Once oscillation starts, the CG of the rod moves up / down. This difference is taken as change in potential energy. This is what I could make out.
excellent teaching
Thank you so much.
The expression for potential energy for the second problem doesn't seem to be consistent for all the terms i.e the spring, sleeve and rod. We need to choose the same initial condition for all the pieces instead of lowest energy positions for each. Since all of them exist as a system. Am I correct?? @ 50 mins
What if you have dof=1 for a simple pendulum? Does it meet the independent condition?
This is a great video. Great lecture on Lagrangian Mechanics.
Hi! i have a doubt with the inertia matrices, the second one is referred about the rod's mass center? shouldn't it be about its own mass center?
Best understanding....
This lecture seems to be very 'In Depth". It gives a good idea of how to completely analyze a system. The derivations may be a bit too in depth for some people.. Perhaps a brief overview of the various concepts would be useful. I can see how this is a lecture that might be appropriate for students who are studying either Engineering or Science.
Thank you, really
Where does the professor takes this force [F(t)=F_0 cos (omega t)] from? (video: 1:06:17) Who does exert (apply) it? Is it a new datum of the problem? Thank you, nice video.
51:56 Why don't have to take account of the length change due to the mass of sleeve?
KX=M2g
X=M2g/K
M2g(L0+L2/2+M2g/K) - M2gX1cos (theta)
I thought the reference should be the final possible state? equilibrium state?
@56.00 why isn't the calculation for kinetic energy for sleeve done wrt A since it is rotating about A and not rotating about G
There are two components to it's kinetic energy. The first is due to its translational energy, and the second is due to the fact that it's rotating about it's center of mass (while simultaneously translating). So you are correct that A is the axis of rotation for it's entire motion, but to simplify the calculations, the translational motion is treated separately from the rotational motion. This is because Izz wrt A of the sleeve would be time dependent in the inertial frame, but Izz wrt G is not. It's essentially using superposition to isolate a fixed point of rotation.
At 53:00, he says I_zz for the sleeve but he writes down I_zz1 instead of I_zz2. Should it be I_zz2?
I don`t know for sure but maybe because of that the moment of inertia for both the cylinder and the rod will be 1/2 M (R or L1) **2
Yes, it should be I_zz2. Look at 1:14:53 😉
At the beginning he refers to better notes "in the cellar" it sounds like. Does anybody know what an where this is? I've got the OCW course materials, but he seemed to me to say there was something better on the net someplace...
Thanks,
-dlj.
He mentions Stellar which is MIT's course management system. It is a platform for learning, course management and collaboration, serving the MIT community. Most of the Stellar site is not accessible to the public.
Thank you very much sir
45:40 Can someone please tell me why the extension is that term?
What is the downward force denoted by just F? Something to do with the damper?
Spend three days to study lagrangian mechanics, this is really amazing
very nice
For the rod problem couldn`t we get the center of mass instead of that way?
how did he differentiate the 1st term for (delta theta)? where does the Coriolis term come from?
There is two stages in engineer´s life; before and after knowing what a Lagrangian is as well as its practical applications. Vandiver is quite a good choice. Thank you!!!
are there lectures on basics of lagrangian and hamiltonian formulations.....if so please provide me the link.
Perfect lesson!!! Thank you very much!!
need explanation a bout Variational Integrators for water waves by luke
At the beginning he mentioned to "visit STELLAR website " for short notes ,,! Please provide the link here !
Very clear explanation thank you, but instead of practical problems I am more interested on HOW Lagrange got into this
dr leonard susskind from standford also has a series of videos on this very topic in his classical mechanics course. if you go to the part in the course where he first introduces hamilton, he briefly comments on what lagrange was doing and why he did it, and then jokes about how he has no clue what hamilton was doing or why he was doing it, or what he was smoking at the time.
step 3 @ 22:18 could be confusing as he wants you to find T AND V, not T PLUS V - a very different thing. Seems a trivial gripe I know, but this could be a real barrier to progress if reviewing notes later
can anyone explain why didn't he take Izz about A for sleeve?
please
Because Izz wrt A would be time dependent in the intertial frame. So instead he used superposition to treat the translational energy and rotational energy separately, and therefore simplify the problem by only considering Izz wrt G, which is constant
can a 16 year old enjoy this class for the love of physics.........YES
I'll try too
You know, it'll be a very big deal if you understand all of this. This requires stuff like calculus of variations!
What courses in mathematics do I have to have in my body before going inside the famous Lagrangian?
Somebody can explain?
Hello Sir! How to formulate Lagrange for thermal system? Thanks
At 50:10 he clearly says that 'it is the change in height' that the rod goes through - so the expression gives 'change' in potential energy.
However, that is not what we are aiming to write; as per my understanding, we are writing the 'potential energy' of the system, not the change in it.
If any of you has an explanation, please share with me.
Anurag Anad: Potential energy can be referred relative to any chosen origin; it is not an absolute quantity as you seem to think. Only changes in potential energy have any physical significance.
The lecture is very useful ... but I need the previous lectures on this subject. please , provide me with possible linkage..... also explanation is wonderful
The playlist is (czcams.com/play/PLUl4u3cNGP62esZEwffjMAsEMW_YArxYC.html). For more info and course materials (assignments with solutions, exams, lecture notes) see the course on MIT OpenCourseWare: ocw.mit.edu/2-003SCF11
Thank you very much
***** you actually responded? wow
MIT OpenCourseWare what book he suggest?
@@sepehrjafari7847 he suggests yo read some Stellar on firt 40 second off lecture, do You hace more detail on ir? Thanks
Thank you