Solutions to Problem 219

[@andrewjustin256]

Mr. Walter Lewis, throughout the comnent section, has stated eating yogurt is a fuel to the brain. He might be pulling our legs but I must state that this is not true; there exists nothing special in the yogurt about neurological health. It's salacious for your digestive microbiome, provided you have probiotocs if you haven't committed their murder. For brain health, I would like to refer to walnuts, high quality fish oil supplements, Omega 3 fatty acids, cod liver oil, etc.. Thank you

[@jaswanthkumar8157]

I think he is telling us in a funny way to observe & prepare the topics properly rather than asking for tips

[@ITS_MR_PHYSICS]

Sir give some advice for ipho prepration like what should be the mindset while studing a topic from basics to ipho level and also tell how to complete any chapter from basic to ipho level

[@lecturesbywalterlewin.they9259]

eat yogurt every day but *never om Fridays* That also wroked for Einstein and for me.

[@ITS_MR_PHYSICS]

@lecturesbywalterlewin.they9259 sir any tips related to studying topics?

[@ITS_MR_PHYSICS]

​@lecturesbywalterlewin.they9259 thanks sir but sir any studying related tips please? , by the way in India we eat curd everyday

[@SandhyaSharma-wr1vv]

@@lecturesbywalterlewin.they9259 bruh🤣🤣

[@mahdibenmahdi4295]

Dr. Walter Lewis, I'm a beginner in physics with a great passion for it, but I don't study it at university. Is it possible to learn physics fully through the lessons on your channel? I would really appreciate any advice for self-study . Thank you!

[@lecturesbywalterlewin.they9259]

you will learn some 1st and 2nd year college physics: some simplified Newtonian Mechanics and Electricity and Magnetism. But that does not include advanced Newtonian Mechanics, Lagragian Physics and advanced E&M and not Quantum Mechanics and not Einstein's Theory of SR and of GR.

[@Quantum_lovers]

sir 🙏 how you understand this complex physics please give me some advice in briefly i want to invent new things in physics

[@lecturesbywalterlewin.they9259]

eat yogurt every day but *never on Fridays* That also worked for Einstein and for me.

[@Naitik_Barnwal]

​@@lecturesbywalterlewin.they9259 😂 Walter sir being Walter sir

[@iitjeeaspirant-o9g]

😂😂😂😂😂😂

[@umeshdeore1854]

Sir why we take turn density instead of total number of turns to calculate the magnetic field due to solenoid ?

[@lecturesbywalterlewin.they9259]

watch my 8.02 lectiures that's what they are for

[@Japneet-uc4ys]

whre is the questions

[@souravsoo]

There's a video of the question 5 days back

[@ramanshushukla274]

Professor is there ether in space or not? Lot of people still claim that it's present there and EM waves travel through it

[@lecturesbywalterlewin.they9259]

use google

[@himanshusahu2151]

Good evening sir i am from India,i am your big big big...... fan

[@Jitendra-i5b7f]

Respect Lewin sir ..I'm from India .I just want to say that I eagerly wait for your videos and learn a lot from them .. Wish u good health:-D

[@ShwetaNavik]

Hello sir , thank you so much ♥️

[@lecturesbywalterlewin.they9259]

Most welcome!

[@SubhajitBiswas-or4kp]

Sir , What is the cause of Normal force ? Can we clearly say which is action and which is reaction ?

[@lecturesbywalterlewin.they9259]

watch my 8.01 lectures, it's all there.

[@SubhajitBiswas-or4kp]

Ok thanks sir ❤

[@adityaprakash6149]

Sir I had a doubt where are these questions, more clearly in which lectures I could find the questions that you discuss on youtube nowadays, also how can I send you my solutions for these questions? (BTW, thanks for your tips for my IPHO preparations you gave to me in the comment section of the video you made on the solution of problem 218.)

[@lecturesbywalterlewin.they9259]

*this is not nursery school*

[@Japneet-uc4ys]

HOW CAN I CONTACT YOU FOR SENDING ANS

[@lecturesbywalterlewin.they9259]

you can only contact me here.

[@rashishsaini50]

Just comment them

[@Japneet-uc4ys]

@@lecturesbywalterlewin.they9259 sure sir thanks for replying

[@MudithaPriyadarshani-m3y]

Thank you sir ❤😊

[@lecturesbywalterlewin.they9259]

You are most welcome!

[@BhargavPadhle]

Sir how to prepare for Physics Olympiad Stage-1?

[@lecturesbywalterlewin.they9259]

ask your teachers

[@sujataray656]

Sir the question is very very

[@abhranildebnath]

Sir I want to read your book For The Love Of Physics

[@lecturesbywalterlewin.they9259]

fiisikis.weebly.com/uploads/5/4/9/3/54939617/for_the_love_of_physics.pdf

[@motivelord]

Hello sir Love from India😊

[@jaswanthkumar8157]

I tried this problem i didnt get it in this way but i will keep on trying, because i love the way you teaching me physics my friend ( If you dont mind me calling you friend sir) and physics teaching to understand physical things in the nature....😊

[@sujataray656]

You just have to apply concept of rotational mechanics.

[@surendrakverma555]

Thanks Sir

[@lecturesbywalterlewin.they9259]

Welcome

[@Japneet-uc4ys]

i know how to solve this questoins but i dont know abt where it was uploaded , am in class 9 , india

[@huyuwgygyu]

see previous video

[@Japneet-uc4ys]

@@huyuwgygyu can you send the link or tell me exactly which one?

[@YannisAlepidis]

Best wishes for a happy new year to all.

[@lecturesbywalterlewin.they9259]

fiisikis.weebly.com/uploads/5/4/9/3/54939617/for_the_love_of_physics.pdf

[@YannisAlepidis]

@@lecturesbywalterlewin.they9259 Thank you very much Prof Lewin! I will download it asap.

[@AvneeshDubey8683]

Good evening sir how to become a millionaire 😀

[@lecturesbywalterlewin.they9259]

win the lottery

[@omnipotato6667]

​@@lecturesbywalterlewin.they9259 😂

[@ThatsBlackidoZ]

Sir youre looking cute teddy bear in thumbnail ❤

[@lecturesbywalterlewin.they9259]

Thank you for the compliment -

[@ThatsBlackidoZ]

@lecturesbywalterlewin.they9259 your welcome sir

[@sujataray656]

. A uniform string of length 20m is suspended from a rigid support. A short wave pulse is introduced at its lowest end. It starts moving up the string. The time taken to reach the support is: (take g = 10 ms-2) Sir I tried to solve but my solution is underrot2 but the correct answer is 2*underrot2,sir kindly solve this question for me.I am a student of class 11th, preparing for JEE. Regards Agnishwar Roy

[@lecturesbywalterlewin.they9259]

watch my 8.01 lecytures - that's what they are for.

[@MadhavNagpal-uy9lv]

I hope this comment finds you with great health. I am Madhav Nagpal an 8th grader from India. I am obsessed with your physics lectures and I aspire to be as knowledge as you in physics. I have planned to make a VTOL fixed wing drone and for that I want to reach MIT for that. I would be glad to receive help from you in reaching out to MIT as well as on mastering physics and making things simple to understand as you do Regards Madhav Nagpal

[@lecturesbywalterlewin.they9259]

reaad MIT's admission website

[@MadhavNagpal-uy9lv]

@@lecturesbywalterlewin.they9259 Respected sir,I have read the website. I want your help to reach out MIT regarding my VTOL fixed wing drone and sir how can I achieve the same level of knowledge and understanding in Physics,no matter how much hard work it takes

[@lecturesbywalterlewin.they9259]

@@MadhavNagpal-uy9lv I cannot help you. I retired from MIT in 2009

[@MadhavNagpal-uy9lv]

@@lecturesbywalterlewin.they9259 No problem sir,I will definitely make my path to MIT. Sir, currently I am studying physics at jee advanced level and I have a trajectory to complete it in 1.5 years. Could you please just give me an idea on how i can match your level of understanding. To sum up I want to learn physics with an intention of actually learning and not with just preparing it for the exams. Please guide on how to learn physics(not specifically for any exam).Thanks for investing your precious time on my comment

[@ld238]

Thank you for the good wishes, I wish you the same for 2025. Did you consider my solution as "entirely correct"? Maybe you remember that you asked me to write my result "differently". I then wrote it in terms of the ratio m/M.

[@sarthaktyagi7440]

1st comment :)

[@divyamsrivastava2468]

This question were taught in class 12 jee preperation in India....❤❤(PW)

[@lecturesbywalterlewin.they9259]

why then did you not send me the correct answers?

[@divyamsrivastava2468]

@lecturesbywalterlewin.they9259 I didn't see the problem earlier...