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
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 🙏👍
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
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
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.
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
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
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😊😊🙏🙏
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.
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 .
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
Timestamp 00:00 Why it is important for JEE Main too ? 00:30 Topics to be discussed in video 01:03 Derivation of Thrust Force expression 06:50 Rocket Propulsion Equation 11:13 Numerical on Rocket Propulsion 13:53 Chain Falling on Floor 17:39 Liquid Coming out of a Pipe/Vessel 20:40 Numerical on Liquid ejected from Vessel
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.
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.
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
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)
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.🙏🙏🙏🙏🙏🙏🙏🙏🙏
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.....
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
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 ?
Sir ur content and effort in teaching Physics is unbelievable extraordinary. if this content is reached to all the people who are preparing for iit jee they consider u as a god
🚀 Session PDF link - bit.ly/3DW2dU4
🔥 PHD SERIES PLAYLIST - bit.ly/3cQSxPT
🔥 GOLD Mine Link - bit.ly/2VhOGFF
Sir electrostatic mai cavity ki question kerya do
1 PhD series please sir
Please sir
Sir cavity per video banao ek
Really thank you so so so .... Much sir ❤️❤️❤️♾️♾️♾️♾️♾️♾️♾️
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
well done dear
#learnlikeneverbefore
Mere Engineering ke second semester aagya vapas aapke video pe , ME101 course h 😅
❤ from IIT GUWAHATI
Drop liya tha kya bhaiya aapne?
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 🙏👍
You're very welcome dear. Make the best use
respcted sir plse make a PHD vdo on conservation of momentum & energy & mass. love u sir u r helping us alot
Its easy only by practice we can command (if ur work energy topic is good)
@@AyushShukla-zg6noLaorets Juaraju
Sir phd series ke videos mains first attempt ke liye bhi dekhne hai ya bas revision videos are sufficient enough ?
Kitna aya 1st attempt me 😢
@@balajiyadav4250tu bata bhai
ch*d gaye guru
amzing video sir .......... and using isro's rocket instead of any other rocket is cherry on top
Underrated 💎 of physics. All concepts are clear sir. Lots of Thanku sir ❤❤
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..
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
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
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.
mast hai sir apke lectures they are really helpful
Glad to hear that
Ok so this is rocket science
😂
😂
No, this not 0.0000000000000001 percent of rocket science.
😂😂😂😂😂😂😂😅
@@manishvaishnav821 We use tensor maths to deal with viscocity of air etc and curl maths etc this is not even the begining
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
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
It's my pleasure
Thank you very much for this crisp and extremely productive session !!
well done on completing it
keep learning and solving
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😊😊🙏🙏
Most welcome dear
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.
Block on Block - th-cam.com/video/lbmDqxiet1k/w-d-xo.html
AC-RL, RC, RLC - th-cam.com/video/74dTY-pzM_o/w-d-xo.html
@@mohitgoenka99 Thank u sir. I was not knowing that it is been uploaded.😀
@@learner3880 its okay dear. I am here to guide you all
Vertical circular motion is also explained in short in wpe one shot video that was not enough but u can go for it
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..❤
7:11 respect isro ❤️⭐
rotation and com revision done...💖💖(thankyou sir ji) charan sparsh
well done on completing it
keep learning and solving
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 .
keep learning & solving
#learnlikeneverbefore
Formula 20:20 water coming out
6:21 formula thurst
10:43 equation
well done dear
keep solving, learning and revising
#learnlikeneverbefore
incredible video. understood the concept really well and in a really short amount of time !
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).
Thank you sir concept crystal clear ho gaya ye vala
excellent
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
ab kaha pe ho bhai? 1 saal hogaya
@@RudraSingh-hmm IIT INDORE electrical
@@Kpk476Congrats brother
@@50_jaykumar95 wlcm bro
Your dedication is superb!! 👏👏
Thank you so much 😀
Timestamp
00:00 Why it is important for JEE Main too ?
00:30 Topics to be discussed in video
01:03 Derivation of Thrust Force expression
06:50 Rocket Propulsion Equation
11:13 Numerical on Rocket Propulsion
13:53 Chain Falling on Floor
17:39 Liquid Coming out of a Pipe/Vessel
20:40 Numerical on Liquid ejected from Vessel
very imteresting sir ....phd series is quite helpful for jee advance
Phd series 😀😀very true sir ...thank you for the session absolutely loved it
Always welcome
in every explanation i could not understand how they write v rel and dm/dt , thank you for telling it patiently
#learnlikeneverbefore
You are the best for physics
No one is better then you at this level you know well what students need
Great work♥️♥️
Thanks a ton
Simple and fantastic way of explanation ♥️♥️
Glad you liked it
2 min. Silence for aspirants who still don't know about this channel. 😀thank you for such amazing video sir.
My pleasure
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.
Do cengage and irodov
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.
Excellent dear. Good to see that
@@mohitgoenka99 Pranam sir
oh sir, you made variable mass concept so easy to understand as this was one of my leaving topics
Glad to hear that
Tq sir💖💖
most welcome dear
Gained Confidence 👍 Thank you so much Sirji 🙏
Always welcome
Thanks sir ❤️❤️
This series is much helpful for all JEE aspirants
Sir please COLLISIONS mai v PHD video bnaiye sir
As soon as possible
Love u sir... These are really helpful..
Glad to hear that
@@mohitgoenka99 can't believe u r real and this humble.. U r my hero...
I don't know how to thank you sir ....... Love you sir..........
most welcome dear
Thank you so much sir....♾️
❤❤♥️❣️❣️❣️❣️❣️💗💗💗💗💓💓💓💓💓💓💖💖💖💖✨✨✨✨✨🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️♾️
keep learning dear
Sir plzz make phd video of instantaneous axis of rotation
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
Physics empire of Mohit goenka sir on youtube 👌 👍 🙌 😀 🙏 😊
👍
This was soo helpful. Thank you sir!!!!
Glad it was helpful!
Great sir ...as always!!
Thanks again!
Concept clear thankyou sir
love you sir dont ever end this channel!!!!!!!!
Fell in love with this SERIES
🔥❤️
Glad to know that dear
22:49 D & C
well done on completing it
keep learning and solving
There should be e negative sign in the calculation of thrust force indicating its direction opposite to Force on ejected mass dm . good video !
Love u dear mohit sir💗
Thank u x 3000
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
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.
@Dheeraj, If you see it logically your eqn seems wrong as Fth and v.dm/dt would cancel out leaving behind a=-g…
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
Sir can you take PhD series on RC and RL circuits please
Revision done ✅
well done dear
keep going forward
#learnlikeneverbefore
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)
Thanks a lot sir, your classes are very usefull for me
Glad to hear that
Respected sir please make a phd video on impulsive force covering all variations
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.🙏🙏🙏🙏🙏🙏🙏🙏🙏
I will try my best
Thanku sir bahut acha laga be conti
Excellent sir ♥️
keep learning
#learnlikeneverbefore
Amazing session sir loved it.
sir is answer of Q1. 600 kg per sec
Q7. 2a/A
Links are given in PDF dear, pls check
Best series sir 👍😇thank you so much sir. Please continue it.... Hope you will complete mechanics soon.. 🙂
Keep watching
The most authentic video 😍
thnx for lovely comment dear
Loved it sir😍
U r great sir❤️
Sir please make a video on rotational dynamics.
Ooh thnx sir.. this topic was skipped in schl.. the rocket propulsion part ..
welcome dear
Thank You so much sir . This series is soo good.
You are most welcome
Jee thing is over
Am back to u for 1st yr
luv frm BITS Pilani ❤
I love you sir and your dedication
EXCELLENT SIR
you the best teacher
Sir please also bring PhD series in rotation
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
Ok!! now time for Doing PhD in COM variable mass 😎👍🏻
That's the plan!
@@mohitgoenka99 sir phd in gauss law too 🤩🤩
sir these topicwise series is very helpfu.. please continue it
check our phd series playlist
I am literally watching each and every PhD series of yours...this is very helpful sir.Thanks for helping us in every way possible
Sir please make a video on work energy theorem and consevation of energy when to use which theorem I am so confused
Thanks a ton sirji .
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.....
the question is solved particularly for t=0
@@mohitgoenka99 got it
Thank you sir
Very very helpful sir 🙏🙏
Keep watching
Ha sir thora bohut to confidence agaya
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
when chain falls, surface applied force on chain
so chain also applied force on surface
Bht shi se smjh aaya sir 😊😊
Thank mohit bhaiya
welcome dear. Make the best use
Sir please upload more phd series video🙏🏼🙏🏼🙏🏼🙏🏼
phd series is so good , thank you 🙏
Awesome video sir!!
So nice of you
✔ day 11 dhanwad ji
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 ?
Very nice class
Sir, can u upload the thermal properties of concept builder
will try dear
@@mohitgoenka99 thanks sir
Nice explanation sir
Thanks and welcome
Very much needed 🙏❤️❤️
Thnx
sir how did you write F = m dv/dt in rocket propulsion
shouldn't it be F = m dv/dt + v dm/dt
Someone who we didnt met struggling for us thank you sirrr
Sir ur content and effort in teaching Physics is unbelievable extraordinary. if this content is reached to all the people who are preparing for iit jee they consider u as a god