Solving one of the toughest Indian exam questions

The question covers rotational motion, angular velocity and angular momentum. Well done to any students who have completed JEE and good luck to those studying. In hindsight the final algebra isn't actually too bad, just annoying at the end of a long question.

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The question:
Two thin circular discs of mass m and 4m, having radii of a and 2a, respectively, are rigidly fixed by a massless, rigid rod of length l = sqrt(24)a through their centers. This assembly is laid on a firm and flat surface, and set rolling without slipping on the surface so that the angular speed about the axis of the rod is w. The angular momentum of the entire assembly about the point ‘O’ is L.

[tibees]

In hindsight the final line of algebra isn't actually too bad and could be done by hand in a few steps but is just annoying at the end of a long question.

[alenkova]

As an engineering student in Europe Im glad I wasn't born in india. My god

[quanta_reletum]

As a JEE aspirant, I have solved many of the JEE Advanced problems but believe me guys they are so painful!
But when you get the answer, your confidence is at next level.

[isnansunuyuntaro]

Respect for those indian high school students who solve that

[leechCat]

Non-asians : This is the hardest question

Indian : Ye toh NCERT wala hai.

[johnsangso]

Wow.... To whoever solved thos questions in India.... A big respect from 🇦🇺

[shashwatsingh]

Never seen somebody so happy doing a jee ques

[devpratap]

*Solves question in 20 minutes*
Jee aspirant: How i am supposed to solve this in 3 min

[santanumandal]

I can still remember while I was solving this question in JEE Advanced 2016 sitting inside IIT Kharagpur (my examination centre). I was able to solve it and the internal happiness was on next level. I looked at the ceiling and thanked the God to help me out. I was actually obsessed with getting admission into my dream institute, Indian Institute of Technology! Today I am a physics research scholar at the best institute of India, Indian Institute of Science Bangalore after graduating from IIT Guwahati (the institute who actually made this question).
I got goosebumps after suddenly seeing this question while scrolling YouTube.
It's been 7 years since my dream started.❤

[Psicose]

Me, a grad student in aerospace engineering: Oh that isn't that hard
Tibees: This is a high school exam
Me, a grad student in aerospace engineering: ._.

[gorgono]

I won't be able to even understand the question in 3 minutes ...

[DrBond]

Selection ratios on an average
Ivy league: 1 out of 30
IIT JEE: 1 out of 150
Edit after 4 months: I cleared IIT JEE 2021😀

[sxransh]

And then there is a *Sharma ji ka ladka* who scores 355 out of 360

[apurvharshit]

*INDIA exams are conducted to reject students not to select*
✔️✔️

[HemanthAnil]

A real brilliant student would’ve left this question in the examination 😂

[nagaming]

Aman Bansal topper of iit 2016 has solved this during the off to him🔥🔥🔥🔥🔥

[Topspeedcraft]

I was going to discredit the toughness of this exam until i saw it's a high school level exam...

[amannanra]

Imagine you just guessed an option and it came out to be correct 😂😂

[metalslug]

This would be a regular exam question in Dynamics in an American university and the professor would normally give us 25 minutes to solve this.
Godspeed to those taking the JEE.

[utkarshsrivastav]

It is essential to note that the concept of double rotation is not in the jee syllabus and the students are usually not taught this. So this also really adds to the difficulty of the question