So what question should I try next? 😀 P.S. I am already working on a modification of this question. I think it's time to introduce an initial push and a frictional force into the dynamics of the system.
@@saritayadav9200i think theres nothing wrong to take sympathy from others l. Considering jee is a very hard and competitive exam so the constant well-being of the mind is very much needed. Moreover ppl should take pride in even preparing for this exam.
completely agree!! I think B being SO close to the real answer as well is tricky. Luckily I think a common mistake would be to calculate the total angular momentum with respect to the z axis which still produces a wrong answer I think. I need to check for d the answer you get if you add the two components to see if it still gives a wrong answer. But yeah... on some of these, you are doubting them until the last second!
Thank you so much mate, for solving this.few months later I'm going to appear 2025jee so this concept would be clear for me with this video. ❤love from India 🇮🇳
@zhelyo_physics but sir I wanted to ask a question. In the second part where we have to tell the angular momentum of the COM of the assembly about the point O , instead of using I×angular velocity Can't we simply use mvr for the point mass rotating about point O in a circle ??
Actually this is not the toughest question bits actually really hyped question The main thing about this questions is that angular velocity vectors and its components and instantaneous axis of rotn Jee has asked tougher question on fluid mechanics and electrodynamics you can have a look on them
Key gave a or ac due to the confusion of the students about the angular momentum, but the single option key given is the absolute correct one, option c doesn't account for the orbital angular momentum associated with the motion, but most of the books just give ac because no one's willing to check the problem and everyone tries to justify the key
@@rishabhavvari1343 may i ask what us orbital angular momentum, cause all im seeing on youtube are videos of atoms which thej classifies for orbital angular momentum
@@redditmemes6648 by orbital i meant angular momentum due to the center of the mass about the point O as L = Lcm + Lself and the given answer just considers Lself
You found the omega of smaller disc by a sneaky😁 and a very basic way for an advanced que then i wondered my dumb mind where is omega com Of assmebly Then i realised the omega of com and everthing about an axis is equal Wow ended half of the goat que of rotation(not for everyone) in a min People like you make me love physics more love you brother 🙏
Loved ur explanation ,sir could u solve more question at level of jee advance but not the previous year rather new question from different book which can be at the level of jee advance
Everytime i see this question, brings back memories of JEE16. I felt the physics paper was very tough, i couldn't clear JEE Adv that year but I did it the following year. Try and try again, a little motivation for future aspirants.
@@zhelyo_physicsI believe memorizing doesn't make the question tricky tho such memorisation shouldn't be allowed to be asked tbh ( or should be provided in the question itself) it's a sad education system here .
@@mxminecraft9410 u don't need to memorise much. If MOI concept is clear then u can easily understand them as well. Now obviously under the JEE time crunch, remembering such values do help
Any alternative way to find w of center of mass, can we use conservation of angular momentum also, might be wrong because I just started studying rotation
You're wrong. For moment of inertia you used formula I = mr² in which you took r as the distance of centre of mass from O. But you can't take r as a location of centre of mass, here r is the RMS distance of all the point mass from O which is also called as Radius of Gyration about the given axis. Reason: In equation I = mr², the term r² is not linear so you can't use the location of centre of mass. If I = mr, then you can use r as a location of centre of mass because r is linear, but in other case you can't use r as a centre of mass. For example, Consider a uniform bar of length L. The location of centre of mass of bar is exactly at centre(middle) of the bar. Let's take the axis Y that passes through centre of mass and perpendicular to the longitudinal axis of the bar. The moment of inertia about Y axis is (mL²/12). But if we use a formula I = mr² considering r as a location of centre of mass from the axis Y then r = 0 because the centre of mass lies at the axis Y. Hence, I = mr² = 0, which is wrong. Therfore, we can prove r cannot be taken as location of centre of mass
Actually I have used those two extensively: ruclips.net/video/ijHzL0MBdhs/видео.html , ruclips.net/video/UbCb_-GtX4E/видео.html Additionally, Halliday Resnick and Physics by Ohanian is amazing. Just some recommendations.
jee advanced have no particular syllabus its just ncert syllbus but as jee ask tough question jee prep books add them as new topic of the chapter , and it becomes new syllabus
Hey Sir I hope you have a good life I also want you to try a question in jee advanced 2017 another question from rotational motion I don't know the questions but it is A twirl in a hand type of question it was hard as he'll and where underrated until you find a small trick of it I want you to figure it out😊☺
Thank you sir for the reply and I hope your next video will have more views because there are many less people in world which love physics and have a value of it
Sir can u pls solve this,really like ur solution ,this question is from jee advance 2020 fluid When water is filled carefully in a glass, one can fill it to a height h above the rim of the glass due to the surface tension of water. To calculate h just before water starts flowing, model the shape of the water above the rim as a disc of thickness h having semicircular edges, as shown schematically in the figure. When the pressure of water at the bottom of this disc exceeds what can be withstood due to the surface tension, the water surface breaks near the rim and water starts flowing from there. If the density of water, its surface tension and the acceleration due to gravity are 103kg m−3 , 0.07 Nm−1 and 10 ms −2 , respectively, the value of h (in mm) is
@@zhelyo_physics yes and that question paper of 2016 was made by IIT Guwahati and there was also an another rotational dynamics comprehension question which was also interesting you should have a look on it
Should the orbital angular momentum not make an angle with orbital angular velocity because they are not supposed to be parallel for unsymmetrical mass distribution
Hm, I agree, excellent point. My solution treats the orbiting assembly as an orbiting point mass. You can also: Find Lo about by finding the moment of inertia with respect to the z axis of the rotating assembly and multiplying it by ω_z which is ω/5 I don't see an easy way of finding this but I can have a go this week. Let me know if you do before me!
Really appreciate Your content.I am Jee aspirant. Such questions are tough and may seem daunting but for us its everyday life. The reason is if you look at our solutions they will seem mechanical and robot like. By continous practice the thinking process is memorized by our brain. That is why personally things like PART A can be solved in a few seconds by just imagining the situation. However Part B is much more difficult as it is not a known or seemingly familiar situation. It was actually Removed from the answer key( It doesnt matter whether you mark the option or not) Its been discussed heavily in this video ruclips.net/video/9zRtldkLVPA/видео.htmlsi=KbnLCVvKqaiHzb_5 Also lastly. Dont take the 2 min per question thing to heart. In reality you dont need to solve every question. solving 80% questions with high accuracy gets you and amazing rank. Also to pass the exam you need 30% or so. Paper attempting strategy also involves knowing which questions to skip.( Personally when I attempted this question as a test I marked part A in 30s and after that i realized it was too lengthy. Thus i only spent 1 min in total and gained all 4 marks :) )
When you calculated the moment of inertia at 5:43 was it like instantaneous? because in the very next second the direction would change! And why didnt you consider the horizontal component of the distance of the center of mass instead?
Good questions! during rotation the magnitude of the moment of inertia should remain constant as the distance 9/5l is not changing during the rotation. I guess the distance l is along the length and considers both the vertical and horizontal components. It's quite a bit easier to treat it this way than to decompose it to separate components to reach the same result, I think! (it's been a while since I solved this question though)
Several reasons - some options were changed as 3D rotation was not part of the syllabus - please correct me if I am wrong. Another possible reason - in different versions of the questions, I can see that the answers have sometimes been swapped, i.e. A in the questions shown here may be a different answer. Please correct me if I am wrong on the reasons. As a physics reason, the solution in the video treats the orbiting assembly as a point mass, so it's something to be aware of.
Which Website. I think you did not read the options. The options can be in different sequences. The correct answer is A Or A, C according to the options in this video . C is actually wrong but they gave it the correct . Because to analyse the motion of this system in the exam hall is really tough as it is not in the syllabus. But who did not mark the option C & marked only A is absolutely the most intelligent so they gave full marks to both the students at that time. Now if you want to know more about Option C then you should talk about it with your physics teacher or you can watch SBT physics channel JEE Physics the video is about 1hour long. But all your doubts about it can be solved.
@@beyond2life951 what is it brother? i forgot to mention that im in a school(sri chaitanya) that has completed 11th class syllabus till COM so thats why i was able to understand this.
@@beyond2life951 bro im in sri chaitanya IPL- batch they teach jee syllabus from 8th actually but i joined in 9th so im learning them now and are you retarded? cuz i literally mentioned that my school completed 11th class syllabus till COM and we having dussehra holidays so we are at a pause
It was controversial question plus we have to slove question like this in less then 5 mins which is quite hard. Plus the things involved doing the question was out of Syallbus . It's one of the hardest not the hardest one. Maths is the hard one in jee .
wow got recommended early😂 btw im also appearing on 2025 jee few months left im willing to show some of my own questions i bet its tougher than these😈 but this rotaional question was out of syllabus though
Solving a question is a situation depending also. Solving questions in an exam hall is different from solving it at home and different when solving it in the classroom.
@@AmarjyotiCR7 because tumhe woh question Krane ke lie taiyar kia gaya tha, sarw concepts and the approch pehle hi sikha diya tha before you attempt that question. Exam scenario different hota hai
So what question should I try next? 😀 P.S. I am already working on a modification of this question. I think it's time to introduce an initial push and a frictional force into the dynamics of the system.
nooooooo not friction
@@mangomanlassi7779 😂😂
What about some problems from IPhO 2022 or APhO 2022?
@@zhelyo_physics 😂😂😂
Yes, Dynamics! I too wanted to analyse the dynamics of this system
Note: JEE ADVANCED is given by high school students at 17 year age
f yeah man.. it's tough
17 to 18
That too there is a time limit to solve most of the questions.
Can't stuck on one question...
Aa gaye sympathy lene
@@saritayadav9200i think theres nothing wrong to take sympathy from others l. Considering jee is a very hard and competitive exam so the constant well-being of the mind is very much needed. Moreover ppl should take pride in even preparing for this exam.
i love how u explain ur thinking process while solving the ques. many teachers online dont do that
respect
thank you so much! I find that's critical to a video/teaching.
Literally true teachers on RUclips have even used inertia tensor & 3d vector concept to solve this which is just pointless
Another thing about this question is that you can't randomly jump on options to check them, have to go in sequence.
completely agree!! I think B being SO close to the real answer as well is tricky. Luckily I think a common mistake would be to calculate the total angular momentum with respect to the z axis which still produces a wrong answer I think. I need to check for d the answer you get if you add the two components to see if it still gives a wrong answer.
But yeah... on some of these, you are doubting them until the last second!
The sequence is totally different on different paper sets (to deter cheating). So you can absolutely jump to options, no reason why not.
Thank you so much mate, for solving this.few months later I'm going to appear 2025jee so this concept would be clear for me with this video. ❤love from India 🇮🇳
thank you so much for the comment!
Seriously this is the shortest & the most precise solution for this question on the whole RUclips 😮
thank you so much for the kind comment. I very much appreciate it.
@zhelyo_physics but sir I wanted to ask a question. In the second part where we have to tell the angular momentum of the COM of the assembly about the point O , instead of using I×angular velocity
Can't we simply use mvr for the point mass rotating about point O in a circle ??
Hey bro ! Loved your enthusiasm while solving that question and making us understand at the same time. Really appreciate your efforts
thank you so much! very much appreciated!
Actually this is not the toughest question bits actually really hyped question
The main thing about this questions is that angular velocity vectors and its components and instantaneous axis of rotn
Jee has asked tougher question on fluid mechanics and electrodynamics you can have a look on them
I'll have a browse, thank you!
Sir actually according to the official answer key the correct answer to this problem is B and D
Bro the answer is correct , maybe you referred.to any other region paper or something
@@Shrek867wdym? The ans in the vid is absolutely wrong
Key gave a or ac due to the confusion of the students about the angular momentum, but the single option key given is the absolute correct one, option c doesn't account for the orbital angular momentum associated with the motion, but most of the books just give ac because no one's willing to check the problem and everyone tries to justify the key
@@rishabhavvari1343 may i ask what us orbital angular momentum, cause all im seeing on youtube are videos of atoms which thej classifies for orbital angular momentum
@@redditmemes6648 by orbital i meant angular momentum due to the center of the mass about the point O as L = Lcm + Lself and the given answer just considers Lself
You found the omega of smaller disc by a sneaky😁 and a very basic way for an advanced que
then i wondered my dumb mind where is omega com Of assmebly
Then i realised the omega of com and everthing about an axis is equal
Wow ended half of the goat que of rotation(not for everyone) in a min
People like you make me love physics more love you brother 🙏
Thank you so much for the kind message! Much appreciated, well done on the problem!
Loved ur explanation ,sir could u solve more question at level of jee advance but not the previous year rather new question from different book which can be at the level of jee advance
Sure! Have a look at this one: ruclips.net/video/y7nJB0L2CJ8/видео.html
Everytime i see this question, brings back memories of JEE16. I felt the physics paper was very tough, i couldn't clear JEE Adv that year but I did it the following year. Try and try again, a little motivation for future aspirants.
well said!
You explained so nicely mann 👍👍👍
11:40 yes sir we have to memorize such formulas
Thanks for the response! Argh, even trickier then, I was looking for an equation sheet in the paper :D
@@zhelyo_physicsI believe memorizing doesn't make the question tricky tho such memorisation shouldn't be allowed to be asked tbh ( or should be provided in the question itself) it's a sad education system here .
@@mxminecraft9410 u don't need to memorise much. If MOI concept is clear then u can easily understand them as well. Now obviously under the JEE time crunch, remembering such values do help
Any alternative way to find w of center of mass, can we use conservation of angular momentum also, might be wrong because I just started studying rotation
You are so smart ,love your content keep it up brother❤❤❤
Thank you!
You're wrong. For moment of inertia you used formula I = mr² in which you took r as the distance of centre of mass from O. But you can't take r as a location of centre of mass, here r is the RMS distance of all the point mass from O which is also called as Radius of Gyration about the given axis.
Reason: In equation I = mr², the term r² is not linear so you can't use the location of centre of mass. If I = mr, then you can use r as a location of centre of mass because r is linear, but in other case you can't use r as a centre of mass.
For example, Consider a uniform bar of length L. The location of centre of mass of bar is exactly at centre(middle) of the bar. Let's take the axis Y that passes through centre of mass and perpendicular to the longitudinal axis of the bar. The moment of inertia about Y axis is (mL²/12). But if we use a formula I = mr² considering r as a location of centre of mass from the axis Y then r = 0 because the centre of mass lies at the axis Y. Hence, I = mr² = 0, which is wrong.
Therfore, we can prove r cannot be taken as location of centre of mass
You have done a great job by explaining this question. But actually the correct answer is only option (A) .
This channel is very very underrated!
Thank you very much for the kind comment!
I want to ask you about Indonesia National physics olympiad question, where should I sent it to you?
Best way is to leave a comment here
Please make a book recommendation video not for any exam but for Physics
Thanks for the idea! Will do
Actually I have used those two extensively: ruclips.net/video/ijHzL0MBdhs/видео.html , ruclips.net/video/UbCb_-GtX4E/видео.html Additionally, Halliday Resnick and Physics by Ohanian is amazing. Just some recommendations.
@@zhelyo_physics halliday resnick just never ends 😭
@@enderman4514for real bro 😢
Its not toughest,Its hard because it was out of syllabus and it is studies in later studies in collese or later
jee advanced have no particular syllabus its just ncert syllbus but as jee ask tough question jee prep books add them as new topic of the chapter , and it becomes new syllabus
Hey Sir I hope you have a good life I also want you to try a question in jee advanced 2017 another question from rotational motion I don't know the questions but it is A twirl in a hand type of question it was hard as he'll and where underrated until you find a small trick of it I want you to figure it out😊☺
Oh! I actually looked at that question yesterday and it looks very interesting : )
Thank you sir for the reply and I hope your next video will have more views because there are many less people in world which love physics and have a value of it
thank you so much!
Sir can u pls solve this,really like ur solution ,this question is from jee advance 2020 fluid
When water is filled carefully in a glass, one can fill it to a height h above the rim of the glass due to
the surface tension of water. To calculate h just before water starts flowing, model the shape of the
water above the rim as a disc of thickness h having semicircular edges, as shown schematically in the
figure. When the pressure of water at the bottom of this disc exceeds what can be withstood due to
the surface tension, the water surface breaks near the rim and water starts flowing from there. If the
density of water, its surface tension and the acceleration due to gravity are 103kg m−3
, 0.07 Nm−1
and 10 ms
−2
, respectively, the value of h (in mm) is
It's 2020 paper 1 question 14
thanks a lot! I will have a look!
This was a question from MIT PHD Physics exam which was done by high school students
Wow has it actually appeared on a PhD exam? I have seen variations of this motion before to study the dynamics/kinematics of this motion before
@@zhelyo_physics yes and that question paper of 2016 was made by IIT Guwahati and there was also an another rotational dynamics comprehension question which was also interesting you should have a look on it
@@zhelyo_physics they do pick some questions from MIT's university's papers like they picked an integration problem from MIT integration Bee
@@sumitvishwakarma1075 brother it was made by iit madras
@@44yash60 Bro 2017 JEE ADVANCE was made by IIT Madras. JEE ADV 2016 was actually made by IIT Guwahati.
Is this system of particles because this answer is similar to that topic
Should the orbital angular momentum not make an angle with orbital angular velocity because they are not supposed to be parallel for unsymmetrical mass distribution
Hm, I agree, excellent point. My solution treats the orbiting assembly as an orbiting point mass. You can also: Find Lo about by finding the moment of inertia with respect to the z axis of the rotating assembly and multiplying it by ω_z which is ω/5 I don't see an easy way of finding this but I can have a go this week. Let me know if you do before me!
its just a game of rotational mechanics , general geometry and center of mass
Really appreciate Your content.I am Jee aspirant. Such questions are tough and may seem daunting but for us its everyday life. The reason is if you look at our solutions they will seem mechanical and robot like. By continous practice the thinking process is memorized by our brain. That is why personally things like PART A can be solved in a few seconds by just imagining the situation.
However Part B is much more difficult as it is not a known or seemingly familiar situation. It was actually Removed from the answer key( It doesnt matter whether you mark the option or not) Its been discussed heavily in this video
ruclips.net/video/9zRtldkLVPA/видео.htmlsi=KbnLCVvKqaiHzb_5
Also lastly. Dont take the 2 min per question thing to heart. In reality you dont need to solve every question. solving 80% questions with high accuracy gets you and amazing rank. Also to pass the exam you need 30% or so. Paper attempting strategy also involves knowing which questions to skip.( Personally when I attempted this question as a test I marked part A in 30s and after that i realized it was too lengthy. Thus i only spent 1 min in total and gained all 4 marks :) )
This is a super interesting insight. Thank you so much for the comment and the valuable info. All the best and good luck!
Damn bro. Im in 11th, a jee aspirant... how do i inculcate this 'intuition' of yours ?
When you calculated the moment of inertia at 5:43 was it like instantaneous? because in the very next second the direction would change! And why didnt you consider the horizontal component of the distance of the center of mass instead?
Good questions! during rotation the magnitude of the moment of inertia should remain constant as the distance 9/5l is not changing during the rotation. I guess the distance l is along the length and considers both the vertical and horizontal components. It's quite a bit easier to treat it this way than to decompose it to separate components to reach the same result, I think! (it's been a while since I solved this question though)
Why are some people saying that your answers are wrong? (Cause I don’t even know who is correct)
Several reasons - some options were changed as 3D rotation was not part of the syllabus - please correct me if I am wrong. Another possible reason - in different versions of the questions, I can see that the answers have sometimes been swapped, i.e. A in the questions shown here may be a different answer. Please correct me if I am wrong on the reasons.
As a physics reason, the solution in the video treats the orbiting assembly as a point mass, so it's something to be aware of.
After this question
My confidence commit suci..de
but the correct answer given on a jee advanced website is b,d or d
Which Website. I think you did not read the options. The options can be in different sequences. The correct answer is A Or A, C according to the options in this video .
C is actually wrong but they gave it the correct . Because to analyse the motion of this system in the exam hall is really tough as it is not in the syllabus. But who did not mark the option C & marked only A is absolutely the most intelligent so they gave full marks to both the students at that time.
Now if you want to know more about Option C then you should talk about it with your physics teacher or you can watch SBT physics channel JEE Physics the video is about 1hour long. But all your doubts about it can be solved.
I was in 2016 batch। Ya thats true
your a great teacher who made me (a 9th class guy) understand this whole question from A to Z great things sir
kam fek
@@beyond2life951 what is it brother? i forgot to mention that im in a school(sri chaitanya) that has completed 11th class syllabus till COM so thats why i was able to understand this.
@@mkrsinfo2859 so why are u bluffing that a 9th grader can understand. 9th grader were not teached COM in their school
@@beyond2life951 bro im in sri chaitanya IPL- batch they teach jee syllabus from 8th actually but i joined in 9th so im learning them now and are you retarded? cuz i literally mentioned that my school completed 11th class syllabus till COM and we having dussehra holidays so we are at a pause
Moment of inertia ???
all explained here if it helps! ruclips.net/video/ienceRAor50/видео.htmlsi=m13rcXbn1_r7J0h7
IIT Guwahati 🎉🔥😳💯
At 3:44 you used Wr=V , why can’t we write Wz(perpendicular distance of centre of disc from z axis)= Velocity of centre of disc?
What?
What do u want to say?
W(omega) is just perpendicular dist×radius of disc.
May i know where are you from??
sure, I am from Bulgaria but I have been teaching in the UK for many years
@@zhelyo_physics nic3
Wow sir you explained nicely ❤❤❤❤❤❤❤❤❤❤❤
thank you for the comment!
@@zhelyo_physics welcome sir❤❤❤🌹🌹🌹🌹🌹❤❤❤❤❤❤
my age is 16 and I am watching it I said though no one wants to know .😊
Sir can you also include ray optics from ipho
On the list it goes 😀
You made it easy now i am going to study COM then i will try it 😂
Imagine an Asian uncles solves it in 1 second 🙏
I came here after tom nightmared you with mat questions😅😅😅😅
😂😂 I should have given him this question!! Maybe next year 😁
@@zhelyo_physics yeahh😂
Anyone not in PHD...... Don't try to go at depth of this question. U will end up with no benefit
hn bhai😂
It has to be done with in 3 mins
@@studyhard-tl4bxI was not meant by that I was just saying we have to do these type of questions within 3 mins
Idk why it is consider as hard
It was controversial question plus we have to slove question like this in less then 5 mins which is quite hard. Plus the things involved doing the question was out of Syallbus . It's one of the hardest not the hardest one. Maths is the hard one in jee .
C is not correct
solution of angular momentum about O is wrong
Could you please elaborate why? Thank you.
Imagine17 yr olds doing it😂
Very difficult to problem to solve at that age, and at any!
stfup no 17 years is solving it , everyone left it
wow got recommended early😂
btw im also appearing on 2025 jee few months left
im willing to show some of my own questions i bet its tougher than these😈
but this rotaional question was out of syllabus though
good luck preparing!
@@zhelyo_physics thanks 🥰
I am solve this question in 6 min in exam
Joker😂
I knew from your English
By marking only option (A) you got full marks. So you thought you solved the question 😂😂.
@@Ayush-q9u cant get full marks with 1 option
@@GOW-h2ythen tell me other correct options.
Not very difficult but a still a good question tho
😂 if you say that, you are either reincarnation of Sir Issac Newton or a liar.
Solving a question is a situation depending also. Solving questions in an exam hall is different from solving it at home and different when solving it in the classroom.
😂 alright buddy
In india 17yrs aged kids solve this type of questions in 5 mins for jee exam
kuchh bhi
@@Ranittttt Maine khud solve Kiya ..Allen par isse hard sawal karwaya jata hai
@@AmarjyotiCR7 because tumhe woh question Krane ke lie taiyar kia gaya tha, sarw concepts and the approch pehle hi sikha diya tha before you attempt that question. Exam scenario different hota hai
@@Ranittttt bhai Maine paas bhi kiya tha jee adv....
@@AmarjyotiCR7 okay congrats. But eisa claim Krna ki yeh qusen 5 minute me solve ho jayega still isn't correct
Class 10 cbse vote here
Sir, A huge respect to you cuz the way u explained this Legendary Q.s was just Outstanding..
Lots of respect to you,😁🫂💯💖💖
thank you so much for the kind comment!
@@zhelyo_physics Your welcome sir 🤗🫂💖