Solution to JEE Advanced Problem 116 - Part 1

Part 1 - Falling rod

[kenadams]

You are the reason why I fell in love with physics... Thank you professor Lewin

[konan]

This is too advanced for me because I just started the First year of high school but I still love it!

[rohankamti]

Thank you sir for electric flux and gauss law lecture. That helped a lot🙏. Love from india ❤️

[BalajiVetriselvan]

Wow!!! Your cap is beautiful and it makes you so handsome :)
At the age of 85 you are teaching us in an very understandable way
Thank you so much for your help sir
I'm a fan of Prof. Walter Lewin
Thanks thanks thank you so much sir

[KurtColville]

Beautiful problem and beautiful explanation. Thanks, Professor Lewin!

[mtreis]

I like the hat, but I always like the clothes you wear. You have one of the most interesting wardrobes.

[johnbruhling]

I've been watching the 8.01 lectures and modules. I first the saw one from 8.03 about EM propogation and traveling waves (I like radio) and then decided to just start at the beginning. They cover concepts we were taught in grade school but obviously not explained at such a high level and I find it all extremely fascinating, thank you so much.

[aparupgoswami]

YOU ARE THE REASON THAT'S WHY I REALLY FALL IN LOVE WITH PHYSICS ❤️❤️❤️❤️❤️❤️

[itsmeamitraj]

sir i am in class 10 and i just started kinematics but further will consider this i love ur voice . may u live long .i will definetly buy that cap from my first salary if i will crack iit .lots of love ❤💞

[Sahid.]

Good vedio.
Love from Assam (India)❤️❤️❤️❤️.

[Jantakichannel]

Excellent work for younger generation. Thanks a lot sir!❤️

[ScholarStream_]

Goes down as one of the best professor of physics.

[rituparnobhattacharjee]

Sir, I am from Tripura State in India and passed out of college 6 years ago. But since the YouTube is available to us in our early college days, we discovered what MIT is! And we discovered you. Your lectures and demonstrations not only taught us the beauty of physics but created a life long memory. Your lectures are nostalgia now. Me and my friends love you and here I am taking the comment space to say a BIG THANK YOU for making our studenthood exciting.

[ShivKumar-hseb]

Love from Bihar in India, 🇮🇳🇮🇳
Thankyou so much sir 🥰🥰 your cap 🧢 very nice sir 😊😊

[srsanderson]

We want these types of problems frequently. Twice a week.

[tigerlion]

Hello sir If we take the kinetic energy teems in x ans y directions and its moment of inertia about its centre we get ghe same result STRANGE? Can you please explain

[ITKALLI]

Really you make me fall I love with physics ...☺☺

LOVE FROM INDIA SIR

[suryashsharma]

Very Very Very thank you Professor Lewin. I am in love with Physics.❤️

[bollyfan]

You can take into account the rotational and the translational KE, but then it has to be computed about the center of mass, which means k = 1/12 rather than 1/3 and you get the correct answer. Basically if you were to compute just rotational KE about the end, then you should use k = 1/3 and no translational KE, because the end is not moving. Alternatively, you can consider the motion about the center of mass of the rod. In that case, k = 1/12, giving a much lower value for rotational KE. The rest is now the translational KE of the center of mass of the rod.
Whether you use the translational KE or not depends on your frame of reference. If you view the rod as rotating about one end, then you are using that end as the frame of reference and it is not that you should not add the translational KE, it is that the end on the wall side is not moving and has zero translational KE. If you use the center of mass of the rod as your frame of reference though, then it is actually moving and has translational KE, but the rotational KE is reduced, because the lower I value about the center of mass of the rod compared to an end of the rod, makes up for that.

[krishnasomalara]

u are an inspiration, I am glad to see how enthusiastic u are
AGE IS REALLY JUST A NUMBER