Variable Mass System | Rocket Propulsion | Chain Falling on Floor | JEE Physics | IIT JEE

[@mohitgoenka99]

🚀 Session PDF link - bit.ly/3DW2dU4 🔥 PHD SERIES PLAYLIST - bit.ly/3cQSxPT 🔥 GOLD Mine Link - bit.ly/2VhOGFF

[@saurabhkantmishra1796]

Sir electrostatic mai cavity ki question kerya do

[@saurabhkantmishra1796]

1 PhD series please sir

[@saurabhkantmishra1796]

Please sir

[@saurabhkantmishra1796]

Sir cavity per video banao ek

[@Stranger_is_back]

Really thank you so so so .... Much sir ❤️❤️❤️♾️♾️♾️♾️♾️♾️♾️

[@SovereignStream]

Sir phd series ke videos mains first attempt ke liye bhi dekhne hai ya bas revision videos are sufficient enough ?

[@balajiyadav4250]

Kitna aya 1st attempt me 😢

[@aparnajhariya3495]

​@@balajiyadav4250tu bata bhai

[@ronak3813]

ch*d gaye guru

[@154bharshbhanushali9]

Mere Engineering ke second semester aagya vapas aapke video pe , ME101 course h 😅 ❤ from IIT GUWAHATI

[@dankkrrish6780]

Drop liya tha kya bhaiya aapne?

[@mohta.]

1)thrust force, F = Vrel * dm/dt (6:30) 2) Rocket propulsion, v = u-gt +Vrel * ln(Mi/Mf) (11:00) 3) chain falling, F = 3Mgx/L (17:30) 4) Water coming out of pipe, F = pAv^2 (p-density,A-area,v-velocity) (19:35) 5) Thank you sir

[@mohitgoenka99]

well done dear #learnlikeneverbefore

[@siddhesh2703]

I can't thank you enough This phd series is so good and the topics are so unique no one literally teach them and skip them but these are very helpful thank you 🙏👍

[@mohitgoenka99]

You're very welcome dear. Make the best use

[@abmini448]

respcted sir plse make a PHD vdo on conservation of momentum & energy & mass. love u sir u r helping us alot

[@AyushShukla-zg6no]

Its easy only by practice we can command (if ur work energy topic is good)

[@ayushdey5494]

​@@AyushShukla-zg6noLaorets Juaraju

[@NeelNitilShrivastava]

sir... for the rocket propulsion case you put "mg" in the eqnn directly but isnt the mass of the rocket changing so wouldnt mg also be changing with time

[@kailashanand5086]

yes! you are correct, the mass of rocket wll keep changing. however, what sir did is correct, and i'll try to explain why. so the equation that sir wrote, is at a random time t. it is a fixed instant in time (note: it is an instant of time and not a time interval). so for that particular instant in time, m is not changing!! so he just wrote the equation for a general time instant, and then integrated. hope that make sense

[@unknowndev7051]

Underrated 💎 of physics. All concepts are clear sir. Lots of Thanku sir ❤❤

[@yuvrajsau]

amzing video sir .......... and using isro's rocket instead of any other rocket is cherry on top

[@prakharpandey3083]

I saw this with 1.5x speed still I understand all things and attempt questions as well. Thank you so much for making ours concept crystal clear..

[@Yourcodehelper]

7:11 respect isro ❤️⭐

[@pravinpawar8033]

mast hai sir apke lectures they are really helpful

[@mohitgoenka99]

Glad to hear that

[@Kpk476]

DOUBT..... IN ROCKET PROPULSION, that relative velocity of gas will be also be negative.. . Then wouldn't it overall become positive as dm/dt is also positive

[@RudraSingh-hmm]

ab kaha pe ho bhai? 1 saal hogaya

[@Kpk476]

@@RudraSingh-hmm IIT INDORE electrical

[@SwarnabDas-rh8mq]

Ok so this is rocket science

[@kalpchajed8]

😂

[@AlishaDas-k7p]

😂

[@manishvaishnav821]

No, this not 0.0000000000000001 percent of rocket science.

[@AdarshSingh-gt2fk]

😂😂😂😂😂😂😂😅

[@garoutheherohunter8613]

​@@manishvaishnav821 We use tensor maths to deal with viscocity of air etc and curl maths etc this is not even the begining

[@saurabhkunkulol6032]

Gained Confidence 👍 Thank you so much Sirji 🙏

[@mohitgoenka99]

Always welcome

[@Abhimanyu_BITSPilani]

I attended the same topic in an offline class in Kota yesterday & I can truly say that these 24mins are at par and better than my 1.5 hr lecture. Thank you so much Sir😊😊🙏🙏

[@mohitgoenka99]

Most welcome dear

[@physicsinfinitybyvadehrasi1608]

I suggest that you use vectors to make the direction of thrust force clear. Like the direction of relative velocity is downwards, say - ĵ and dm/dt is negative so that thrust force is directed upwards that is along ĵ

[@faisalahmadmir1225]

Bohat bura lagta hai jab itne ache content ko itne kam views hote hain.. I hope and I pray one day (soon) this channel will get views in millions..❤

[@learner3880]

Please provide session on PhD in 1.AC,RL,RC,RLC circuit 2. Block over block problem 3. Vertical circular motion 4. Circuit analysis. This lecture was amazing. I was able to understand everything. My these topics are only weak. If they get strong then mine physics would be done.

[@mohitgoenka99]

Block on Block - kzbin.info/www/bejne/opPQdaSunsqnZ80 AC-RL, RC, RLC - kzbin.info/www/bejne/bWXHhYxjpd-AldE

[@learner3880]

@@mohitgoenka99 Thank u sir. I was not knowing that it is been uploaded.😀

[@mohitgoenka99]

@@learner3880 its okay dear. I am here to guide you all

[@mahendra601]

Vertical circular motion is also explained in short in wpe one shot video that was not enough but u can go for it

[@devidkonwar7736]

4:10 relative velocity always be addition of two velocity when both moving in opposite direction(Vr=Vgas+Vrocket). Let's apply in a practical situation: When you are in inside a car moving 100km/h, opposite car moving towards you with 100km/h, You will get to see opposite car seems to be moving with 200km/h towards you is the relative velocity.

[@v4explorers184]

very very helpful video, You are building confidence in so many students.. Good Job , Iam a mother of two IIT aspirant students, iam learning from u and teaching them. THanks a lot

[@mohitgoenka99]

It's my pleasure

[@satendrasingh9855]

Sir can you take PhD series on RC and RL circuits please

[@jayeshb9323]

Phd series 😀😀very true sir ...thank you for the session absolutely loved it

[@mohitgoenka99]

Always welcome

[@harshkumargupta8831]

Amazing session sir loved it. sir is answer of Q1. 600 kg per sec Q7. 2a/A

[@mohitgoenka99]

Links are given in PDF dear, pls check

[@pratikgoswamiiitbombay8767]

Thank you sir concept crystal clear ho gaya ye vala

[@mohitgoenka99]

excellent

[@shashanktiwari4971]

Sir plzz make phd video of instantaneous axis of rotation

[@Atul_Tiwari1]

Sir please make a video on rotational dynamics.

[@PriyanshuDhami-ch1sj]

Thanks sir ❤️❤️ This series is much helpful for all JEE aspirants Sir please COLLISIONS mai v PHD video bnaiye sir

[@mohitgoenka99]

As soon as possible

[@Dr.owaisAIIMS]

Fell in love with this SERIES 🔥❤️

[@mohitgoenka99]

Glad to know that dear

[@madhavsingh9500]

Physics empire of Mohit goenka sir on youtube 👌 👍 🙌 😀 🙏 😊

[@mohitgoenka99]

👍

[@ringo4556]

Thankyou sir ye concept 1 year chod rakha tha ajj crystal cler ho gya thankyou so much sir ,pls PhD on RC circuit pls sir

[@dakshrara6009]

in every explanation i could not understand how they write v rel and dm/dt , thank you for telling it patiently

[@mohitgoenka99]

#learnlikeneverbefore

[@pranavtejankar5947]

Thank You sir , I loved the way you explain the concept in detail . The topic of Rocket Propulsion🤩 was my weak part , but now with the help of this video I have cleared it and it's no more my weak one .

[@mohitgoenka99]

keep learning & solving #learnlikeneverbefore

[@Stranger_is_back]

Thank you so much sir....♾️ ❤❤♥️❣️❣️❣️❣️❣️💗💗💗💗💓💓💓💓💓💓💖💖💖💖✨✨✨✨✨🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️

[@mohitgoenka99]

keep learning dear

[@akshatchoudhary8747]

9:14 sir why did you put -ve sign for Fthrust v relative is already -ve and dm/dt is also -ve so the Fthrust will +ve(upwards).

[@vinayakujjwal9029]

Respected sir please make a phd video on impulsive force covering all variations

[@Jatt080]

✔ day 11 dhanwad ji

[@kunalsharma-ez7pb]

Very nice class

[@gopalmishra8441]

very imteresting sir ....phd series is quite helpful for jee advance

[@mayanksingh1262]

You are the best for physics No one is better then you at this level you know well what students need Great work♥️♥️

[@mohitgoenka99]

Thanks a ton

[@rashmipriya9221]

Sir I didn't understand how thrust force is applied on the surface when the chain was falling ...... Because what I understood that thrust force is something that works more like a action reaction system

[@mohitgoenka99]

when chain falls, surface applied force on chain so chain also applied force on surface

[@thebravepirate]

Your dedication is superb!! 👏👏

[@mohitgoenka99]

Thank you so much 😀

[@pritampramanick282]

Ha sir thora bohut to confidence agaya

[@cricketdevotee9674]

Sir please upload more phd series video🙏🏼🙏🏼🙏🏼🙏🏼

[@tharlover554]

Sir please also bring PhD series in rotation

[@Sona-t8p]

love you sir dont ever end this channel!!!!!!!!

[@mayanksingh1262]

Simple and fantastic way of explanation ♥️♥️

[@mohitgoenka99]

Glad you liked it

[@harshdeepsinghsisodiya2543]

Dear sir in this rocket propulsion why we are taking m in gravitational force(Mg) as constant because as the rocket is moving upward it will loss the fuel so the mass also decrease so m should be variable

[@theseusswore]

incredible video. understood the concept really well and in a really short amount of time !

[@sakshambhatnagar7386]

Jee thing is over Am back to u for 1st yr luv frm BITS Pilani ❤

[@tharlover554]

I don't know how to thank you sir ....... Love you sir..........

[@mohitgoenka99]

most welcome dear

[@J_Prince24]

Revision done ✅

[@mohitgoenka99]

well done dear keep going forward #learnlikeneverbefore

[@mishrashivedra3357]

Thanku sir bahut acha laga be conti

[@sarthak4632]

Sir please make revision vedio for fluid mechanics

[@prabhun8106]

oh sir, you made variable mass concept so easy to understand as this was one of my leaving topics

[@mohitgoenka99]

Glad to hear that

[@yuvrajshukla4616]

Sir please make a video on work energy theorem and consevation of energy when to use which theorem I am so confused

[@Jems-uo9ni]

Bhaiyaa COLLISION par ek video bana dijiye please 🙏❤️

[@harshgarg2529]

Sir should I watch and prepare it for jee main or should do after mains because I have less time so I am doing topics for jee main only

[@fnsjit733]

Ooh thnx sir.. this topic was skipped in schl.. the rocket propulsion part ..

[@mohitgoenka99]

welcome dear

[@chandanmaths1729]

Concept clear thankyou sir

[@LostZoro798]

Thank you sir very much for this wonderful lecture on variable mass system....I am preparing for jee advanced and I have completed hcv and moving on to some better books.. Sir can you Kindly suggest some good books.. I am 2026 aspirant.

[@weirdo992]

Do cengage and irodov

[@modinarendraa]

sir i have doubt , in that chain falling problem how can we write v = (2gx)^1/2, because its not just falling under the gravity , thrust force is also acting on it which will depent on its velocity . when i wrote force equation for that falling chain it was like , xg - v^2 = L* dv/dt . is that correct ?

[@nidhipatil9537]

Formula 20:20 water coming out 6:21 formula thurst 10:43 equation

[@mohitgoenka99]

well done dear keep solving, learning and revising #learnlikeneverbefore

[@RahulSharmaSingularity]

There should be e negative sign in the calculation of thrust force indicating its direction opposite to Force on ejected mass dm . good video !

[@hartikarora9851]

Thanku sir I used to be very afraid of this topic, but today I understand this topic nicely 😊😊

[@yupsplus2768]

phd series is so good , thank you 🙏

[@motivationguru1689]

you the best teacher

[@eagerbat3800]

Also Please make a video on Toppling .

[@dhruvgupta9530]

Ok!! now time for Doing PhD in COM variable mass 😎👍🏻

[@mohitgoenka99]

That's the plan!

[@mr.fahrenheit1420]

@@mohitgoenka99 sir phd in gauss law too 🤩🤩

[@abhijeetyadav9717]

2 min. Silence for aspirants who still don't know about this channel. 😀thank you for such amazing video sir.

[@mohitgoenka99]

My pleasure

[@sussushi]

sir please also take the question in which sand falls on top of a moving cart...

[@payalthakur6065]

Thank mohit bhaiya

[@mohitgoenka99]

welcome dear. Make the best use

[@thomas3146]

Love u dear mohit sir💗 Thank u x 3000

[@mysticalpreacher941]

Make similar video on linear momentum conservation

[@asifraza8298]

Bhaiya Fluid chapter pe phd karwaiye plz , selected questions karwadijye

[@arghadeep469]

Sir please PhD on oblique collision

[@mohitgoenka99]

noted dear

[@introvert__boy]

make phd on ydse plz ....

[@NoMatterWhat279]

Sir @8:18 Why did you write net force =ma Bcoz as mass is changing,Why Is it not mdv/dt+vdm/dt=Fth-mg? Pls reply sir

[@mohitgoenka99]

in the previous slide we already derived that due to varying mass thrust force is Vrel*dm/dt. So in this one we simply used it.

[@kshitijvispute6792]

@Dheeraj, If you see it logically your eqn seems wrong as Fth and v.dm/dt would cancel out leaving behind a=-g…

[@kshitijvispute6792]

And if you’d want to see it conceptually… Just go by the basics.. use impulse momentum eqn: initial momentum+ impulse= final momentum you’ll get an eqn F.dt=m.dv -u.dm on simplification where F is external force(here gravity), just divide the eqn by dt and thus you’ll get F=ma-u.dm/dt.. and on putting F=mg a=u.dm/m.dt +g

[@NOTHING_In_]

may you do complete chapters instead of just revisions?

[@Vedant_Bharatvasi]

Best series sir 👍😇thank you so much sir. Please continue it.... Hope you will complete mechanics soon.. 🙂

[@mohitgoenka99]

Keep watching

[@parthsarathidixit5648]

Bhaiya H vector or B vector me kya difference hota hai magnetism me

[@brawlera6738]

Sir if there is friction , how will we calculate it as mass is variable?

[@kailashkushwaha9296]

I love you sir and your dedication

[@kenechi__]

Sir thank you very much for making such a great content.For your gold mine series...my 11 th syllabus has covered 1/3 in just 1 month.Thanks a lot sir.

[@mohitgoenka99]

Excellent dear. Good to see that

[@kenechi__]

@@mohitgoenka99 Pranam sir

[@nishantpawar2049]

Excellent sir ♥️

[@mohitgoenka99]

keep learning #learnlikeneverbefore

[@letscrackit1065]

Thanks a ton sirji .

[@funnycatflick7115]

21:50 sir is question me Mass to decrease karega time ke sath to ye variable hua na , acceleration integration se karna padhega na???? sir please clear my doubt.....

[@mohitgoenka99]

the question is solved particularly for t=0

[@funnycatflick7115]

@@mohitgoenka99 got it Thank you sir

[@RaushanKumar-lg9em]

Please provide 15 questions or more on particular topic sir.🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏

[@mehulgoyal7727]

9:17 But v(rel) is also negative, right?? 21:58 I know it won't have much effect on the answer but while calculating velocity of efflux(applying Bernoulli's theorem) why did we ignore the velocity of liquid at the top(as the area is given and is comparable)?? This will give the answer, a=200/999(very close)

[@dipteshkp01]

sir these topicwise series is very helpfu.. please continue it

[@mohitgoenka99]

check our phd series playlist

[@laiba6139]

This was soo helpful. Thank you sir!!!!

[@mohitgoenka99]

Glad it was helpful!

[@Aamon_bbx]

Hello Sir, I am a dropper and I just started every thing from scratch from December , as of now 10% syllabus are completed in all 3 subjects. Should I go on to do the entire syllabus ?? For jee 2022

[@dhruvmohanshukla8933]

No

[@mohitgoenka99]

Watch are guaranteed 60 marks in physics video

[@vu2281]

Tq sir💖💖

[@mohitgoenka99]

most welcome dear

[@RaushanKumar-lg9em]

Thanks sir for topic explaination. I was wondering on youtube from previous years to study physics topics wise. Please continue it sir and please upload 2-3 topics video in a day.🙏🙏🙏🙏🙏🙏🙏🙏🙏

[@mohitgoenka99]

I will try my best

[@stusongdio9033]

Great sir ...as always!!

[@mohitgoenka99]

Thanks again!

[@AayushAnand-z3w]

Sir , i have a doubt. We derived the thrust force expression in a condition where there was no external force due to which we were able to use momentum conservation. But in point no. 2 ,since the rocket is going directly against mg ,therefore we must not be able to apply consv. Of momentum . So, i feel that the expression of thrust force could have been changed in the rocket propulsion case. This doubt can be silly if i could not have been able to grab that minute concept which led to this .

[@AdityaSingh-oj4fg]

The most authentic video 😍

[@mohitgoenka99]

thnx for lovely comment dear

[@yasimrashidi4375]

EXCELLENT SIR

[@user-y3y5p]

Thank you so much sir 😊😊 Completed COM with 3yr pyq ❤

[@aayushmishra48]

Love u sir... These are really helpful..

[@mohitgoenka99]

Glad to hear that

[@aayushmishra48]

@@mohitgoenka99 can't believe u r real and this humble.. U r my hero...