Ulf Haller's Solution to Problem 195

very easy problem

[@ulfhaller6818]

Thank you dr. Lewin for taking the time to explain my solution!

[@lecturesbywalterlewin.they9259]

You are very welcome

[@EdwardSnowden125]

​@@lecturesbywalterlewin.they9259please keep making this kind of content sir. It would be great if you'd explain gyroscopes and it's details with the maths behind it in more detail(skipping the basics that you already explained in 801 if i recall correctly). Much love and respect from India ❤

[@DmaestroErwin]

You’re simply the best. This problem was relatively easy, but the beauty in the explanation remains just that - beautiful. Your lectures are almost poetic, I did say almost, but it did just land me my first teaching position today. ❤

[@oldtvnut]

Dr. Lewin, I feel you should not be too disappointed in the number of answers, as there may be viewers who do these problems only occasionally for recreation.

[@sunshinemagagula1284]

Your Channel motivated to start my own channel. ❤❤❤❤ 🔥🔥🔥🔥

[@Sunflower-rg1nt]

there is no explanation of how much your past works mean to me sir. you really help me with physics and physics really helps me understand this world we happen to live in. i have upcoming exams. i try my best to get a good job in the future. thank you sir you inspire me. i really hope you see this because i really want to let you know how grateful i am for your past 8.02 courses.

[@lecturesbywalterlewin.they9259]

Glad to hear that

[@SLee-bo8fw]

Hello professor, thank you so much for your effort to inspire so many people around the world to love physics.

[@lecturesbywalterlewin.they9259]

My pleasure!

[@mohdshoieb244]

Morning Professor Lewin.I'm a NEET-UG Aspirant from India.I find your lectures easy to go for my work.And I find them quite useful.What more do I need to do? Plz infer to this Mr Professor.. Love from India💟

[@CarlFriedrichGauss1]

Still doing it at 88 WHAT A LEGEND.

[@user-fb8xj7wj3d]

Damn,,,,Sir your explanation is just❤❤❤❤❤

[@lecturesbywalterlewin.they9259]

Glad to hear that

[@MrAminmohamed]

Do you think gravity could be seen like a way to minimize void between bodies ?

[@drmantistoboggan2870]

Hi Doctor Lewin, I have only recently found your great channel. Ironically i only found it because a flat earther tried using your lectures as evidence for his silly claims. In the end though he has done me a favour because your content is fantastic. Thank you so much for all your hard work.

[@lecturesbywalterlewin.they9259]

Excellent!

[@georgejetson4378]

Please don’t try convincing ME that the earth isn’t flat with all of that physics mambo jumbo!

[@vaibhavDubey-rl3xg]

Sir, I saw in a video that after rotating a rim wheel, you sat on a chair and the chair started rotating, but sir, in this situation all the force is internal and internal force never provides motion, then how did the chair start rotating?

[@user-bm3rj6mm7z]

Sir you are greatt❤❤

[@aninditabiswas6895]

U r the best physics teacher ❤

[@user-fh9hg8id6i]

Mera name Sourav Kumar hai aur main India se hu i like you sir ❤😊

[@avikhatiwada1732]

Thank you sir

[@positive1061]

We use centre of mass analysis to calculate Gravitational potential energy of a wire of mass m and height h held upright to be mgh/2. Why don't we use centre of mass to calculate elastic potential energy of a hanging wire? It's actually d²g²Al³/6Y Is it just mathematics or anything else?

[@aninditabiswas6895]

Hii sir I am from India ❤

[@musicronaldo5525]

You ate my favourite physics sir THE WALTER LEWIN

[@L.NEVER.LOSES.]

ate?

[@michaelbruning9361]

In part c) we get a closed circuit of a coil and two resistors R2 and R3 in series. For this closed circuit you can choose a clockwise or counter clockwise edge orientation. I suggest to choose a counter clockwise orientation, because the physical direction of the current is counter clockwise. That orientation means, that for positive values of a current I, the current flows counter clockwise and for negative values of I clockwise. In this case the current I3 = I2 > 0 flow counter clockwise. To choose in a closed circuit with two resistors in series for R3 a counter clockwise orientation and for R2 a clockwise orientation and then say I3 = -I2 is a bit strange. Why easy if complicated is another option ?

[@lecturesbywalterlewin.they9259]

You can change the circuit so that I2 and I3 are in the same direction (please do it). *You will then see that the answers to a, b and c change.* *In other words you have changed the problem into a different problem.* This is my last msg on this topic.

[@techoo123]

Ok 🫡 professor

[@ulfhaller6818]

@michaelbruning9361 The only reason is that we will point out that the current I2 take another path in part c) than in part b). In part b) I2 goes in the direction of the arrow shown in the figure to ground. But in part c) I2 goes, as you pointed out, counter clockwise in the upper loop opposite the arrow for I2 because the ground, or minus of the battery, is disconnected.

[@pankajkumar-db3mx]

Nice sir❤

[@Nilak-dy8jk]

hi sir, I have a question (not related to physics) I read in class 11 and I have a doubt in mathematics. The question is 'Find the minimum value of 2^(sin^2theta) + 2^(cos^2theta)' The lowest value of both sin^2 theta and cos^2 theta is 0 so, the answer must be 2^0 + 2^0 = 1+1 = 2. But the answer in book is different. Am I right or wrong?

[@positive1061]

That's wrong sin²theeta and cos²theeta cannot get the value 0 for the same theeta. The question is probably asking for what theeta it'll achieve minimum value and the minimum value itself.

[@ulfhaller6818]

f(x) = 2^sin²x + 2^cos²x Take the derivative: => f’(x) = ln 2· sin 2x · (2^sin²x - 2^cos²x) f’(x) = 0 => 1) sin 2x = 0 => x = ± n·π/2 2) 2^sin²x - 2^cos²x = 0 => x = π/4 ± n·π/2 1) => f = 3 (max value) 2) => f = 2√2 (min value)

[@user-bv7ru3un2z]

HELLO SIR I AM FROM INDIA . I AM DALITE FROM LOWER CASTE

[@sotecluxan4221]

[@Villain_Arc_Has_Started]

Professor I am eating yogurt everyday except on fridays, but still I am not getting smart what to do??

[@lecturesbywalterlewin.they9259]

Eistein and I both did it for about 20 years

[@dineshkumarsharma2450]

Sir kindly explain the working of megaphone (sound) Physics..

[@lecturesbywalterlewin.they9259]

use google

[@utkarshsingh894]

sir can u plzz make a video on how to study physics and understand the concepts and get in love with physics I am a student everytime I try to study physics I find it very hard to understand the subject I don't know am I studying it in a wrong way or something else. plzz consider my request

[@lecturesbywalterlewin.they9259]

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

[@sajeedkhan2168]

Great!

[@magnuswootton7368]

compute the resistances normally and just say the top line is 0.

[@abhilashkulagude1426]

When incident ray passes normally why does snells law fail

[@lecturesbywalterlewin.they9259]

if incident ray is normal to the surface, Snell's Law works fine. both angles in medium 1 and 2 are then zero degrees.

[@abulkhayer4898]

Sir I'm from class 8....and I want to know about the Föppl von karman plate theory.....can you please explain it to me.....not able to understand using Google.....

[@lecturesbywalterlewin.they9259]

I can't help you - I too would use google

[@abulkhayer4898]

Okay sir thank you sir......

[@EsnaeenJannat]

I WISH I COULD MEET YOU

[@hasanbhai1101]

🌼 Hey Professor, I just noticed something: your channel has only one short/reel video. In your long lectures, there are lots of gems; you should put them into shorts/reels, as today's generation is interested in these things. I'm a video editor. If you want, I can generate reels for your KZbin channel, and I can also create social media pages for your wonderful work. If you are interested, you may drop down your email below; we may proceed from there. Looking forward to your response!

[@lecturesbywalterlewin.they9259]

that 1 sort video was not made by me. Frankly, I don't even know how to make a short video. Several of my videos are less than 5 sec yet they are not listed as short videos. What would you be able to do for me and how would that lead to more active viewers? Be specific!

[@hasanbhai1101]

​@@lecturesbywalterlewin.they9259 What I will be doing is extracting clips from your Long Lecture, creating shorts that capture the essence of your lecture. I will add subtitles and, if necessary, incorporate visual graphics. I will craft eye-catching titles and create attractive thumbnails, along with using relevant hashtags. By implementing these strategies, your channel will attract a larger audience than it currently has. If you are interested, I can send samples of 2 or 3 reels. If you find them suitable, you may consider hiring me. If you could provide me with your email, I can send you my resume there. Thank You!

[@hasanbhai1101]

What I will be doing is extracting clips from your Long Lecture, creating shorts that capture the essence of your lecture. I will add subtitles and, if necessary, incorporate visual graphics. I will craft eye-catching titles and create attractive thumbnails, along with using relevant hashtags. By implementing these strategies, your channel will attract a larger audience than it currently has. If you are interested, I can send samples of 2 or 3 reels. If you find them suitable, you may consider hiring me. If you could provide me with your email, I can send you my resume there. Thank You!

[@lecturesbywalterlewin.they9259]

@@hasanbhai1101 @hasanbhai1101 • 28 minutes ago You wrote: What I will be doing is extracting clips from your Long Lecture, creating shorts that capture the essence of your lecture. *my lectures are carefully composed and well balanced* - *if parts are left out or shortened they will be ruined*

[@hasanbhai1101]

@@lecturesbywalterlewin.they9259 Yes, Professor, it is true that your lectures are well thought out. While it may be challenging to condense them into shorts, video editing is also an art. Physics is a beautiful subject, yet it can be summarized in a few equations. If you would like, I can send you a few samples, and then the decision is yours.

[@darkshadow569]

It's just a 9th STD question

[@anonymous-zt9xw]

Lol it is LR circuit

[@anonymous-zt9xw]

Hello professor. Im not interested in mechanical physics also can't do good in that plz give some tips.

[@lecturesbywalterlewin.they9259]

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

[@HEHEHEHEHEHEH23]

Hello sir I'm first here :D

[@xgrow911]

Sir I think. Yo u should study islam...

[@lecturesbywalterlewin.they9259]

I have done that after which I decided to become an atheist

[@L.NEVER.LOSES.]

@@lecturesbywalterlewin.they9259 🤣

[@xgrow911]

sir what is your opinion on palestine and israel issue@@lecturesbywalterlewin.they9259

[@xgrow911]

Sir what Is your opinion on Palestine and israel issue@@lecturesbywalterlewin.they9259

[@trickyepithet9122]

​@@lecturesbywalterlewin.they9259😂

[@techayush6639]

This question is look like my class x cbse board exam question 😀

[@surendrakverma555]

Thanks Sir