JEE ADVANCED 2017 SOLUTIONS - Find out how to solve the TWIRLING RING problem

[@amiyancandol4499]

Sir I got for PP1 19:51 (a) : counterclockwise (b) : W for PP2 20:11 2mglsinø/π for PP3 21:01 √6g/lcosø for PP4 21:51 I got without any approx √(g/2htan²ø+rsinø/2) now after approx r

[@babitamishra524]

Great man

[@HOPE-kw9ej]

How to find average torque in 20:11?

[@amiyancandol4499]

@@HOPE-kw9ej net change in angular momentum by total time

[@ayushsarangi4095]

Bhaiya best books for jee advanced? (Including PYQ)... PG 6 books n SBT 2 volumes ?? Can we skip irodov n krotov....as I found mannnnnyyyy questions to irodov n krotov of same difficulty (specially in mechanics) in PG n SBT.... ? Also I m doing Allen scores, AITS n mechanics of Pathfinder n have done inpho 2019 to 2011 paper

[@HOPE-kw9ej]

@@ayushsarangi4095 I think that will be enough to build ur concept

[@RamizZamanJEEPhysics]

JEE people were themself confused with this question🤣🤣 As usual top notch explanation sir

[@yatharthgupta6468]

Guess who liked before watching? 🙋

[@pranjalrathoreiitkharagpur2201]

Postmortem of the concepts done successfully 🕵️👨🏻‍⚕️...reports says.... concepts are all safe and healthy

[@PHYSICSSIRJEE]

😂

[@babitamishra524]

Yeah now that's hilarious 😆🤣

[@pranjalrathoreiitkharagpur2201]

@@utkarshsrivastav2987 question was body which was killed by sir's intelligence , and concepts were its organs...we were checking for the concepts.

[@utkarshsrivastav2987]

Ohh

[@ClarkKentfromKansas]

Sir, your hardwork won't go in vain. Yeah there are still loads of students who don't know about this goldmine but the numbers are steadily increasing. You will surely taste the sweet fruits of your efforts soon. We can't thank you enough for providing such high levels of education at no monetary cost. God bless you.

[@AbhishekKumar-rr7od]

Always spot on with the choice of problems,its indepth analysis and explanation. Love your videos sir.

[@eduscopefoundation9066]

kzbin.info/www/bejne/gYiooph9Z8iprpI

[@ayushsarangi4095]

Bhaiya best books for jee advanced? (Including PYQ)... PG 6 books n SBT 2 volumes ?? Can we skip irodov n krotov....as I found mannnnnyyyy questions to irodov n krotov of same difficulty (specially in mechanics) in PG n SBT.... ? Also I m doing Allen scores, AITS n mechanics of Pathfinder n have done inpho 2019 to 2011 paper

[@akshatsharma8151]

Are you Abhishek sir from vmc?

[@tilakshukla8962]

When in my 11th standard I was solving the this problem and came up with same doubt of unbalanced torque. Afterwards I read the article of gyroscopic precession and that cleared my doubt. I'm just happy that I found it out on my own. 😄

[@mayankshekhar9631]

Precession*

[@madhushringi4217]

Amazing! Take up all the best JEE ADV. Physics PYQ Problems ... It would be very helpful specially bcoz of the Perfect Practice Problems

[@balkrishnajha1524]

Splendid work sir! Loved your work. These small videos work 1000 times better than long 2 hrs videos. Brilliantly explained.

[@ponbapanda2935]

"JEENIUS" -I'm gonna use this pun forever

[@PHYSICSSIRJEE]

Someone used it on one of my earlier NTA videos I think. It stuck with me 😃

[@mohitanjana1000]

Problem pp4 time stamp 21:51 solution write two equation along vertical and horizontal Nsinx+Fcosx=mg (vertically), (x=theta)(sorry i do not have theta symbol in phone) other equation in horizontally mπ^2(Htanx-rcosx), where π=omega we need to find) as per given in the question htanx>>>>R then we can neglect rcosx in the above equation finally torque equation about centre of mass FR=T but torque is dl/dt where dl is rate of change of angular momentum , so now angular momentum of ring That is mw^r it has two components one in horizontal and second is vertically (slightly you need 3 d visualization by curling your finger along omega you got direction of angular momentum parallel to curved surface of segment of cone ) now after doing components you get to know that vertical component doesn't change hence no torque due to that and horizontal component is changing , so we can write T=dL/dt=π×Lsinx(concept of circular motion visit sir video where he taught to write equal da/dt=W×a (cross product) and one equation is rw=htanxπ(not these equations is only valid here because htanx>>>>>r otherewise these ring is tilted and hence we cannot v=rw here) with these three variable with three equation you will get anwer as √g/2h tanx

[@ParwindarSingh555]

Believe me sir. You are one of the gem in physics. The depth and clarity you have on subject is really awesome 🙏🙏

[@PHYSICSSIRJEE]

Thank you 🙂 and I try to keep improving 🙏

[@Arnav-vt6xm]

​@@PHYSICSSIRJEEsir can't we do this 2017 q by ICR INSTANTANEOUS CENTRE OF ROTATION

[@amiyancandol4499]

Sir you won't believe ! but , 2-3 months back me and my friend were discussing 3d rotation together and when we came across this qn same doubt of torque balancing in vertical dirn came to our mind😅 and then after some surfing we found its relation with gyroscopic precession! Really awesome to see you today with the same topic, more concepts cleared 😁.

[@ishansingh2391]

Op

[@amiyancandol4499]

@@ishansingh2391 nimish tha

[@masoomladka8017]

Sir you always op🙏

[@krishgujarati7091]

Was desperately waiting for this video. Thank you so much sir 😀

[@vardaandua3585]

Sir the way u explain is amazing , I can definitely understand why your students get single digit ranks

[@kapilaagrawal2560]

Ek number Macha dala🔥🔥

[@as.if_0077]

OP as Always 😍

[@Legacies87]

Yesterday I came across this channel and realize how beneficial this channel and its content is.Truly I'm speechless to express my gratitude for this sort of content,but nevertheless why there is only few followers of this channel.This channel is truly helpful for JEE aspirants.

[@yatharthgupta6468]

Awesome explanation And congratulations for 9k suscribers, 10k soon ❤️🙌

[@Nxck2440]

I'm not a JEE student but I once tried to write down the equations for hoola hoop dynamics but couldn't figure it out. This was very interesting thank you!

[@shoaibmobassir9677]

Thanks sir 😊😊.. I was waiting for this question..

[@ks2372]

thank you sir jee 😊😊

[@metablaze3523]

there is always something to learn in your videos. too good

[@atikshagarwal2649]

Sir you made me love rotational mechanics. Thank you very much.

[@yuvrajjoshi3842]

Thank you so much sir ,most wanted question

[@krititalreja675]

You are a JEENIUS sir! Thank you for making the explanation so eJEE to understand sir 😆

[@PHYSICSSIRJEE]

Thank you JEE 😁🙏

[@triggeredskeletonbankey8864]

@@PHYSICSSIRJEE jee 😅😅

[@nukli8253]

Thank you for your efforts 🙏🙏🙏🙏🙏🙏❤️❤️❤️ Liked from all my 3 accounts 😀🙏🙏🙏🙏🙏🙏

[@ProTeachers]

Such a great channel. I also started making very nice problems on physics. Needs your blessings sir.

[@AnkushKumar-jf3wu]

Thanks sir, which ever video I watch of yours, I learn something new. Which feel amazing

[@ray_7594]

Sir is being creative with video thumbnail -' Jeenius' 👌👌

[@vijaymishra-ir7zf]

While considering torque, centrifugal force must be counted

[@uttambose2723]

Sir congrats for 9k love the content 👏👏👏

[@mrityunjaysharma3496]

Great explaination sir 👍

[@riturajsharma7108]

Sir plz take some Problems on optics, by the way this channel is very healthy

[@anishtakshak6515]

Thank you sirji 😊❤

[@sarthakmishra1483]

Thanks for the amazing analysis sir ❤️😀

[@nihanth9145]

Awesome analysis sir 😍😍

[@vedarthbhawsar4286]

Amazing sir jee.... I like your postmortem 🤩🤩... Thank you sir jee

[@emc8630]

Awesome sir

[@uttambose2723]

Sir can you please make a video on electromagnetism involving conductors rotating neither in magnetic or electric field initially...

[@niranjanmenon1771]

Thanks for ..such type of analysis 🙂👍

[@harsha4444]

9k subscribers congratulations sir

[@Verylastchangs_older_brother]

Sir got 3 correct Enjoyed the video 💜

[@vaishalibanerjee7343]

20:50 option-3

[@palashraut9465]

Same i got that too

[@huzaifaabedeen7119]

Please suggest me a KZbin channel for chemistry for JEE advanced

[@_shwettt]

🤩🤩🤩🙏🏻🙏🏻thank u sir really helpful

[@royorange9691]

It was not recommended to it though... I just wanted to know the physics behind this so I searched for it Thank god I found the correct video

[@emc8630]

Sir can u please make a seperate video on gyroscopic precession??

[@eduscopefoundation9066]

kzbin.info/www/bejne/gYiooph9Z8iprpI

[@babitamishra524]

I was thinking 🤔what will be the correct question ,so thanks for this video.Can you please make euler equations

[@ASN_9320]

9:07 sir, how can you say the ring is in pure rotation about the centre of the smaller circle? The point of contact at the shown instant will become the farthest point from point of contact at a later instant, half of time period of revolution

[@PHYSICSSIRJEE]

So ? What's the problem ? Instantaneously in pure rotation doesn't mean all points will move continuously in circular motion. Here CM is the only point in circular motion and other points are in circular motion wrt CM . So their distances from axis are different at different instances . Eg : rolling ring on flat surface, does every point maintain its distance from ICR at every instant?

[@ASN_9320]

@@PHYSICSSIRJEE Clear now. Thanks alot unexpected and quick reply sir jee 😀

[@aaryansahu2003]

Eagerly waiting for this video..Hats off to ur presentation and dedication for video..So much analysis.Thanks sir

[@ayushsarangi4095]

Bhaiya best books for jee advanced? (Including PYQ)... PG 6 books n SBT 2 volumes ?? Can we skip irodov n krotov....as I found mannnnnyyyy questions to irodov n krotov of same difficulty (specially in mechanics) in PG n SBT.... ? Also I m doing Allen scores, AITS n mechanics of Pathfinder n have done inpho 2019 to 2011 paper

[@ayushsarangi4095]

Are bhai aap toh nitin sir se ho na?

[@SachinKumar-cd1sg]

Please upload more JEE advanced pyq before jee advanced 2021

[@satyamkumarmal7783]

19:54 Q.a opt B According to me !!

[@babitamishra524]

It can be recommended to have a series for fun physics video as an episode serial ,that would catch some attention and many will enjoy that too

[@mamtamittal3051]

Sir can you give a soln of practice problem 3 about the point of contact with the ring

[@HOPE-kw9ej]

Waisa average torque wale ka ye ho sakta h kya (Change in toque )/∆theta Ye sahi h kya logic For 20:11

[@PHYSICSSIRJEE]

*Change in L

[@HOPE-kw9ej]

@@PHYSICSSIRJEE sir is mine logic is correct??

[@PHYSICSSIRJEE]

@@HOPE-kw9ej change in torque is wrong

[@HOPE-kw9ej]

Sir like as a vector torque is change it's direction every time when it travel in circular orbit for theta =π. So like I thought of change of troque by total change in theta in it movement from @=0 to @=π

[@PHYSICSSIRJEE]

@@HOPE-kw9ej average Tau = ∆L/∆t . Think , where your answer meets this , if at all

[@hellohello4360]

Waiting for your next video

[@gayetriranipan3627]

Nice sir...

[@swathik8422]

sir @12:31 how did you write N to be providing centripetal acceleration for whole body,only for point of contact right it will provide?

[@PHYSICSSIRJEE]

N is external force on the body . Here , in JEE assumption, they considered it to be responsible for circular motion of CM

[@vedant6598]

Sir I have a doubt I am leaving mechanics section for jee advanced preparation because I have a good confidence in remaining syallbus so sir in this last 20 days shall even solve mechanics PYQ'S or shall I leave it !! Please respond sir I am in bit confused state .....😔😥

[@PHYSICSSIRJEE]

Leaving mechanics will be foolish

[@vedant6598]

@@PHYSICSSIRJEE Ooo.. ok sir

[@pawanbhardwaj3153]

Sir Thanks for explaining in such a lucrative manner. I have a doubt regarding ICOR in case of pure rolling . Suppose a body is pure rolling with acceleration ‘a’ and angular acceleration alpha. Since ICOR is a point in space which is momentarily at rest and may be accelerated. But in case of pure rolling, would ICOR be bottom most point of the body or the top most point of the ground or the point in space at the intersection of both body’s bottom most point and ground top most point . And what would be the acceleration of that ICOR ? Please reply i am having this doubt for more than 2 years and none could clear it.

[@sumithasuresh4597]

Caption op! 😀

[@abhinandanjokhe1716]

Sir I want to study theory from you how can I?

[@thefreevoice808]

gyroscopic effect

[@thefreevoice808]

sir 19:51 pp1 answer i got b and b

[@akshatjindal1508]

Sir, I solved this question on my own and had a problem in answer key as in my archive for 17) C option is given. 😅 Also for 18) I thought that the ring cannot be at rest due to unbalanced torque. I talked with my friends who had earlier done it also got in confusion. Final searching this question on net, I got this video😅😂. Thanks

[@PHYSICSSIRJEE]

Thank you for letting me know that it helped you 🙂, keep watching and learning.. please recommend and share this channel with your friends 👍🏼

[@hahahahha-e5z]

sir wont the mw^2(R-x) force balance it out? since we are assuming it to be at a small angle, there will be a component of that force towards normal vector of the ring, which will balance out the couple....if you perform this experiment with any key-chain and rotate it abt your finger, you can see that if u are fast enough, it is almost horizontal, and the situation there is exactly the same as in the question

[@ankitroy8567]

omg..........got the 2nd one same as that of jee...but fr I would not attempt this ques during exams

[@Viper-zs4lc]

Sir please take up more and more analysis of previous years as alpha and omega as omega is so close to us🔥

[@yehaa1296]

19:48 ncert? Where in ncert pls tell me 😅

[@PHYSICSSIRJEE]

Rotation chapter, blue box. Please kindly search

[@rajdeepnaha1242]

Maja agaya sir jee

[@haneekmohamed7709]

Tnx sir

[@godisgood2482]

Sir please give me your brain🥺🥺😅😅 so i can top in jee advanced in physics section i am really weak in physics sir. 🥺🥺 please give some tips can i be like you??

[@PHYSICSSIRJEE]

I didn't top in JEE , my rank was 251 , and I got least in physics among the three subjects then 😂

[@riturajsharma7108]

@@PHYSICSSIRJEE sir i will be happy with air 251 , so plz give me your brain😅

[@PHYSICSSIRJEE]

@@riturajsharma7108 😂😂

[@godisgood2482]

@@PHYSICSSIRJEE what i can't believe you got least in physics amongst 3?😨😨😨😨😨

[@heeraksharma1224]

@@PHYSICSSIRJEE sir, what made you start teaching Olympic ad physics? Great video the way 👍

[@shivgurjar9602]

Target achieved

[@PHYSICSSIRJEE]

Video coming today 🙌🙂

[@shivgurjar9602]

Waiting

[@equalcell1555]

🤩🤩

[@dank5488]

Ok

[@equalcell1555]

@@dank5488 ok

[@uttambose2723]

First like btw

[@BhautikiGyanamJAISHREERAM]

Sorry bro I'm first 😎

[@uttambose2723]

When I got notification I was first bro it said zero likes and zero views

[@uttambose2723]

Anyways the first does not matter just share and like and subscribe to sir sorry sir I just used your line 😀 anyone who loves concept rich videos of physics can't resist to promote lol

[@mohitanjana1000]

Sir i have one doubt as there is no slip at point of contact we can write w°r=W(of ring)R there velocity will be same

[@abhirupkundu348]

Sir I got PP1 19:51 (a) :counterclockwise,(b): W PP2 20:11 option (c) 2mglsinphi/ pi But Sir I got stuck in the PP3 question 21:02 . Could you plese give a hint?

[@PHYSICSSIRJEE]

Please check pinned comment

[@alkakumari9211]

sir how to study from you for 11th and 12th ? do u teach in offline classroom also ? pls reply

[@PHYSICSSIRJEE]

Online only now... Please check my app

[@hasnas8385]

sir..if we consider r

[@shauryagupta3990]

sir that means the ring is performing both translational and rotational motion?

[@anushkrajbordia1873]

The topic taken is interesting... another cool question just like the 2016 rotation question...but sir I think you have mentioned ambigous at the start of the video for ambiguous...

[@PHYSICSSIRJEE]

I will correct it 😊. Thanks for pointing out. Ambiguous spelling became ambigous😂 , unintentionally

[@jigyansudash5403]

Ambiguous is the correct spelling

[@vandanakayande4419]

Students favourite :Alpha and Omega Series...6000 views in 3 days..🔥🔥😎

[@anuragtiwari2854]

Rajat golechha op in the chat!!!

[@ThePhysicsGuru]

Unfortunately the answer keys given in exam was wrong. But very high thought level question.

[@komalsharma-oc5vq]

Rajat golechha op !!!!!! 😀😀

[@ashutoshsingh3894]

If you gain something from this vedio , then please even like the vedio and subscribe the channel.

[@akscs373]

understood....thnx sir❤️.... Can u also pls start INPHO solution series (especially 2008 to 2015) .... it will be very useful 🙏

[@PHYSICSSIRJEE]

I will try . 👍🏼

[@yatharthgupta6468]

Sir how could we prove that the point of contact of ring with the small circle (instanteous point of contact) remains same at all the time...I found using analysis by assuming angular velocity of ring to be w' and applying no slipping conditions to figure that w'= wo..however in most of the solution like urs..we are directly saying that the point remains same( of ring with the small circle) and hence w are equal...please explain a bit sir.. thanks

[@leopard8296]

Sir, I have a doubt which is slightly off topic, please answer it. We know that an induced electric field comes from a time varying magenetic field. Say, I got a problem where dB/dt is non zero, but the problem has already mentioned an external e static field. Is it possible to apply Kirchhoff's voltage law now? Although the E static field is conservative, but a non - conservative field is present already in the situation , and we can't apply KVL in scenarios where non- conservative fields are present, simply because the change of Potential along the loop(closed) won't be zero anymore. Please clarify.

[@PHYSICSSIRJEE]

Please refer to modified KVL from IRODOV theory book for such cases

[@leopard8296]

@@PHYSICSSIRJEE thank you for replying sir

[@leopard8296]

@@PHYSICSSIRJEE Sir, one more question. I guess you are directing me to Irodov's edition of "Basic Laws of Electromagnetism". I wanted to ask, would I find it directly in the current electricity section, i.e. the very section where he has explained both of Kirchhoff's laws, proving one of them as well.

[@triggeredskeletonbankey8864]

Sir what is the meaning of " ORIGINAL" in your post I see many times ?

[@PHYSICSSIRJEE]

Think 🙂

[@triggeredskeletonbankey8864]

@@PHYSICSSIRJEE depth in problem

[@PHYSICSSIRJEE]

@@triggeredskeletonbankey8864 original means a problem created or modified by me for my students in the past

[@triggeredskeletonbankey8864]

@@PHYSICSSIRJEE thanks sir

[@ayushsarangi4095]

Original means original 😂

[@Ferb56]

20:54 c

[@sarthakpanda7530]

i think we can find answer to that optics problem of jee advanced 2020 since line of sight is mentioned.i think exact distance is not important and angle of sight to each surface is important which is 45degree using shift (both along horizontal and vertical to each surface) i got 4.49 cm as final answer.Thank you sir

[@PHYSICSSIRJEE]

Please go through both the videos , IRODOV one and my solution , why the optics problem has no unique answer . Once you go through completely , you will be convinced . Whatever I have to say and prove , I have done without any doubt in those videos. You may comment there. Nothing more to say 🙂👍🏼

[@PHYSICSSIRJEE]

Also , the 45 degree logic is also wrong . I have proven it convincingly there in the video .

[@sarthakpanda7530]

sir i commented there my doubt.thank you

[@PHYSICSSIRJEE]

@@sarthakpanda7530 I have replied there 🙂👍🏼

[@ShivamSingh-zl2jh]

Rajat golechha op!!!

[@Prodbybah]

Sir after irodov what should i do for inpho time is also not very much remaining please help sir pls guide 😭🙏😭🙏🙏🙏🙏

[@kakuthism]

Sir, I have sent u on ur email my observation on calculation of K.E. As per my calculation the angular velocity of centre of mass of circular ring around circle of radius (R-r) and angular velocity of circular ring about its centre of mass will not be same. w' about c.m. = w (R-r)/R And K.E. = (1/2)mw^2(R-r)^2 + (1/2)mw^2(R-r) = mw^2(R-r)^2 i.e. option C should be correct. May be I m doing some mistake. Please correct me where I m wrong

[@PHYSICSSIRJEE]

Omega could be anything , the solution was done assuming it is same for repetitive and stable motion . One of the main reasons why JEE deleted the question.

[@PHYSICSSIRJEE]

What you wrote is also one of the cases possible as I already stated in the second pdf shared below the description on hula hoop ( please refer to equation -4 in page 4 of pdf ) . But as I said that is under one possible assumption (case) . Multiple answers are possible here

[@kakuthism]

@@PHYSICSSIRJEE sir, I just considered a general case of two rings touching each other (smaller ring's outer surface is in contact with bigger ring' inner surface. Smaller ring is stationary(fixed) and bigger ring is rotating (rolling) on outer surface of smaller ring without slipping. This case should be equivalent to JEE question given assumption

[@PHYSICSSIRJEE]

@@kakuthism smaller ring need not be fixed . Here it's purely rotating . It's surface speed is speed of finger

[@PHYSICSSIRJEE]

@@kakuthism Also , the ICR for small circle and big circle is the same center of small circle . In my assumption , As the points of contact on both big and small circle are at same fixed distance r from this ICR , Omega should be same for no slipping condition

[@masoomladka8017]

🔥🔥

[@yashvardhansahu7000]

glad no one is here.....

[@aryanpandey1310]

I never understood this thing here that.. why u assume that angular velocity with respect to center of mass of ring will be same omega ...I can't feel that it will be equal to omega....please check it..

[@PHYSICSSIRJEE]

It's one of the special cases under which the problem is solved for stable and repetitive periodic motion of the ring . With no information provided , that's the best assumption . Other cases for stable motion are also possible