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High School/JEE/NEET/IPhO Physics | 17-19 Yrs

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  1.  
    2. Good evening Sir, Why is it that in case of a hollow cone, we take the height of the elemental ring along the slant height, while in case of solid cone, we take the height as dy along the central axis of the cone?....Also, while I was trying to calculate COM of sphere, I tried to find it using the angle made from the x axis(horizontal diameter of sphere) but I got a wrong answer. Is there any reason why that method wouldn't work or it is a mistake from my part Sir? I would be grateful if you could please clarify once. Thanks a lot.
    7 months ago by Anurag Nandi

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  2.  
    3. Sir, What is mass moment but?
    2 years ago by Ashwani Pandey

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  3.  
    4. Sir I am not getting why the C2 and C0 are zero when taken from C1 as when we combine them we get the whole circle. Sir can you please tell some more about it so it gets cleared?
    2 years ago by Sidharth Jay Chakrat

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  4.  
    5. approach of taking theta for elemental disc valid here like in the case of hollow cylinder ??plz reply
    3 years ago by

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  5.  
    6. sir some times cant see your hand written letters so please write bigger or give the option of zoom in it is my humble request sir
    3 years ago by Shriya Chowdary

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  6.  
    7. What is geometric centre and what is the meaning of the uniform bodies?
    3 years ago by Arman Dwibedy

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  7.  
    8. sir do I require to solve Hc Verma after these lectures
    3 years ago by

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  8.  
    9. How did you consider elementlal mass to be M/p×dthehta
    4 years ago by Amritesh

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  9.  
    10. sir how to do when we take many hollow hemispheres ?
    4 years ago by Yash Veer Nagar

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  10.  
    11. can the limits be from 0 to -pi/2 ?
    4 years ago by Yash Veer Nagar

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  11.  
    12. sir what did you said at 1:05 could not hear the voice clearly you said something like "we consider element in polar form " am i correct if so then pls tell what is polar form
    4 years ago by Yash Veer Nagar

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  12.  
    13. too many will consume a lot of time as well as data......plz sir modify the app with 2x feature just like youtube.
    4 years ago by indranil roy

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  13.  
    14. Very nice explanation easy to understand
    5 years ago by babu vanapalli

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  14.  
    15. https://drive.google.com/file/d/1Lff4OXXIWpIc9deo6Xp8zeGzrgtBAaBT/view?usp=drivesdk sir i think the question in this link which is from your book has the answer wrong
    5 years ago by Harsh Shukla

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  15.  
    16. Sir if we adopt method similar to that we use in hollow cone we are getting a answer 3((R^2 H^2)^1/2)/4. Why?
    5 years ago by Abc

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  16.  
    17. Sir if we adopt method similar to that we use in hollow sphere we are getting a answer R/2
    5 years ago by Abc

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  17.  
    18. dude your video are more useful and interesting then my aakash institutes well qualified teachers..
    5 years ago by Bhavya Khajuria

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  18.  
    19. sir can we just learn com of dis ,ring directly
    5 years ago by ishita gupta

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  19.  
    20. is this enough for JEE Advanced
    5 years ago by Arun Prasath
    Ans 1 ->
    your concepts from the video should be clear and solve irodov you will gain confidenc
    5 years ago by Sarju Panchal

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  20.  
    21. two particles of mass m and 2m projected horizontally towards each other with velocity 10 and 5m/s respectively from 10 m high building having seperation between the buildings to be 60m . they collide in air and got stick each other in air . thr distance from A where both balls lie is. A is the ground place where is 10m building containg mass m.
    5 years ago by undefined

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  21.  
    22. sir why you did"t find x coordinate of com
    5 years ago by Saurav Tiwari

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  22.  
    23. In physics for kvpy what we have to study in optics
    5 years ago by Gaurav Bhargava

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  23.  
    24. please enable playback speed option
    5 years ago by Prateek Chauhan
    Ans 1 ->
    You should open these videos on YouTube app . Write the name of the chapter , it will be displayed on youtube as playlist
    5 years ago by Ujjwal Kar

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  24.  
    25. Answer should be 21a/10
    5 years ago by Ankit Shaw

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  25.  
    26. Why we have integrated on surface(dx) while on height(dy) in hollow cone.
    6 years ago by Mayank Goyal

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  26.  
    27. sir v and v are looking same so please understand their respective meanings
    6 years ago by raghav dixit

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  27.  
    28. sir i think it might be an aliter but i am not getting answer we can write equation-1 as mod(vc)=v{v^2+20^2} also by using formula velocity of centre of mass we get equation-2 as vector(vc)=(80/14)i+(10v/14)j so again equation-3 from 2 mod(vc)=v{(80/14)^2+(10v/14)^2} so equating 1&3 we can get answer but its not coming.......... please help
    6 years ago by raghav dixit

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  28.  
    29. How is mass moment different from moment of inertia in an SOP?
    6 years ago by Anushka Kulshrestha

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  29.  
    30. center of mass basedonfolding
    6 years ago by Prince Raj

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  30.  
    31. where can i get q set solutions
    6 years ago by sai durga harsha vardhan

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  31.  
    32. sir i cant derive on my own , what should i do?
    6 years ago by eshwar

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  32.  
    33. 1)can impulsive forces do work? 2)is energy and momentum conserved in case of impulsive forces
    6 years ago by Naresh Jethwani

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  33.  
    34. Sir how to find maximum extension in following case with reference to the frame fixed to center of mass: Two small blocks of mass m1 and m2 are connected by a spring place on smooth horizontal plane .Discs are set In Motion with initial velocity v1 and v2 whose directions are mutually perpendicular and in same horizontal plane..
    6 years ago by snehil verma

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  34.  
    35. Sir why work done by gravity and pseudo forces in centre of mass frame is zero?
    6 years ago by snehil verma

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  35.  
    36. Can we do this question using this concept A uniform solid right circular cone has its base cut out in conical shape such that hollow is right circular cone on the same base of radius r. Find what should be the height of the hollow so that the centre of mass of the remaining portion may coincide the vertex of the hollow part
    6 years ago by Kartik V.

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  36.  
    37. Can we do this question using this concept A uniform solid right circular cone has its base cut out in conical shape such that hollow is right circular cone on the same base of radius r. Find what should be the height of the hollow so that the centre of mass of the remaining portion may coincide the vertex of the hollow part.
    6 years ago by Kartik V.

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  37.  
    38. From a circular disc of radius 4R two small disc radius R are cut off. The centre of mass of the new structure will be?
    6 years ago by Prajeii

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  38.  
    39. Sir which formula should we use what you gave us... Or the m1r1 m2r2....../m1 m2....mn
    6 years ago by Alok Shukla

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  39.  
    40. where will the answers be displayed
    6 years ago by aswin gawtham

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  40.  
    41. why is x not intergreted in second step??
    6 years ago by aswin gawtham

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  41.  
    42. Sir, why are we integrating it from 0 to pi/2 ?
    6 years ago by Aditya Soni

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  42.  
    43. the question is incomplete its nowhere written that the mass m2 is a square and even by geometry we cant find that out
    7 years ago by siddhant bhatt
    Ans 1 ->
    For uniformity widht of structure E is taken constant everywhere... with that it is clear that it is a square of side a...
    7 years ago by Physics Galaxy

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  43.  
    44. Why is it so that for hollow cone we took dx but for solid cone we are taking dy. Elaborate please.
    7 years ago by Amrita Mazumder
    Ans 1 ->
    Why we have integrated on surface(dx) while on height(dy) in hollow cone.
    6 years ago by Mayank Goyal

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  44.  
    45. So how can we put area as mass while calculating the x coordinate
    7 years ago by Siddhant Mahapatra

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  45.  
    46. i didn't undestood that why area is proportional to mass?????
    7 years ago by piyush gera
    Ans 1 ->
    As the body is of uniform thickness its mass = density x volume = density x area x thickness Here in above relation density and thickness are constant so mass is directly proportional to area...
    7 years ago by Physics Galaxy

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  46.  
    47. how we can get the solutions to the question set.
    7 years ago by Onkar Tiwari onkartiwari
    Ans 1 ->
    queset solutions are not released as of now... when available we will inform our users via mail...
    7 years ago by Physics Galaxy
    Ans 2 ->
    Are the Qu.Set solutions released?
    3 years ago by

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  47.  
    48. sir i could not get the same answer when i use angular coordinates?
    7 years ago by Joel Varghese
    Ans 1 ->
    In this case how you are using angular coordinates, pl explain, we will let you know the error...
    7 years ago by Physics Galaxy

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  48.  
    49. Why is COM of half disc located at a/2-4(a/2)/3pi
    8 years ago by Divya
    Ans 1 ->
    Shouldn't it be just 4(a/2)/3pi?
    8 years ago by Divya
    Ans 2 ->
    COM of disc is at 4R/3pi and here R=a/2 and half disc center is at x=a/2
    8 years ago by Physics Galaxy

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  49.  
    50. HI Sir could u please explain why the continuous body is considered to be a discrete body in the beginning? positive comments from frndz accepted!!!! thanks
    8 years ago by Arnab “Red Raider” Chakraborty

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  50.  
    51. sir we can take origin any where we want ???????????????
    8 years ago by Nitesh Guleria
    Ans 1 ->
    Yes You can Take origin anywhere try yourself by taking origin in some other place and calculate the answer and see the result
    8 years ago by Gurpreet Singh

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  51.  
    52. not able to see the video
    8 years ago by Sharath Chandar Devendran
    Ans 1 ->
    gud
    8 years ago by Aayush Srivastava
    Ans 2 ->
    awesome
    6 years ago by Mahaksh Kanhaiyalal Trivedi

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  52.  
    53. In a system of particles,Center of mass is defined as a point about which the mass moments of all particles of the system is 0.Sir,can u please explain why it is so??
    8 years ago by Parash Goswami
    Ans 1 ->
    it is a physics law sir has explainedcleared
    8 years ago by Niranjan Reddy

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  53.  
    54. sorry sir for asking such a silly question i got it myself after using a little brain of mine. :-) Thanks for the lessons
    8 years ago by Simran Malhotra

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  54.  
    55. Sir how is r = Rsin(theta) ? Please explain
    8 years ago by Simran Malhotra
    Ans 1 ->
    It's obvious....Observe that the ring being a circle only has centre on the y axis.Now just think about rsin(theta) geometrically......U r done
    8 years ago by Aayush Srivastava

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  55.  
    56. how did u get 9a/2?????
    8 years ago by Satyapramod
    Ans 1 ->
    the com of the block of mass m2 is at a distance 4a +a/2=9a/2
    8 years ago by Aditi Gupta

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  56.  
    57. In the second example how can you say that the angle is 37
    8 years ago by Satyapramod
    Ans 1 ->
    Its because tan theta=3/4.therefore theta=37
    8 years ago by Satyapramod

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  57.  
    58. why the limits are from -pie/2 to pie/2 cant we take it from 0 to pie/2 ???
    8 years ago by suvit sharma
    Ans 1 ->
    i mean 0 to pie ...
    8 years ago by suvit sharma
    Ans 2 ->
    theta is the angle from vertical not with horizontal
    8 years ago by Ajay Sabarish

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  58.  
    59. I didn't get how the value of summation of m(i)x(i) came ???????????
    9 years ago by RITIK ASHUTOSH BOMPILWAR

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  59.  
    60. in calculating center of mass of solid hemisphere,while we are considering an elemental disc of mass dm then its distance from origin should not be simply y rather center of mass of disc which is it should be 4y/3*pi. like u did in case of calculating center of mas of disc with help of elemental ring, you used y coordinate as 2y/pi.
    9 years ago by MD.YASIR FEROZ KHAN
    Ans 1 ->
    NO... the centre of mass of disc is at its centre as it is complete disc not half disc so we take its distance from centre as y only not 4y/3pi... carefully watch the video again, hope you will get it...
    9 years ago by Physics Galaxy

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  60.  
    61. what is center of mass of a uniform rod
    10 years ago by niteesh kumar
    Ans 1 ->
    length/2
    10 years ago by Devang
    Ans 2 ->
    L/2.
    9 years ago by MD.YASIR FEROZ KHAN
    Ans 3 ->
    IF THE ROD IS OF LENGTH L THEN CENTER OF MASS LIE AT L/2
    9 years ago by NAVYA

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