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

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  1.  
    2. sir, in eq [3] you have put the value of 2T in stead of T the value of a should come 2g/5 2u
    1 weeks ago by Heeral

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  2.  
    3. Best
    3 weeks ago by

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  3.  
    4. How we find solutions of given exercise
    3 months ago by Anshu

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  4.  
    5. h
    4 months ago by Arkajyoti Bhattacharya

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  5.  
    6. Respected Sir, can we assume weighing machine to be massless? If not could you explain how force 'N' acts on cabin?
    4 months ago by

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  6.  
    7. sir, this solved example video is private and unavailable...
    6 months ago by

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  7.  
    8. Clear!
    1 years ago by

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  8.  
    9. HOW TENSION IS EQUAL TO FRICTION IN THIS CASE ?
    2 years ago by

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  9.  
    10. Sir, which pen do you use? And by the way, thank you sir for these great lectures. I'm in class 8 and this is really helpful for NSEJS.
    2 years ago by

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  10.  
    11. Please explain why we took the parallel component of the force at 1:04
    2 years ago by

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  11.  
    12. We are asked to find the force applied by block A on B, then the mass should be takes as 10kg right? Why did we take it as 5kg?
    2 years ago by

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  12.  
    13. I had a doubt that how did Sir derive the first equation? He said that we can use virtual work method, and that total work done be tension on block is zero. But then Sir wrote Work as Product of Tension and Acceleration. I am unable to understand the concept behind it.
    2 years ago by

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  13.  
    14. Superb and useful
    3 years ago by

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  14.  
    15. Sir can you please explain the dynamics of projectile motion perpendicular direction of water splash when a Vehicle lands on water surface,maximum range how to calculate?
    3 years ago by Soham Purkait

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  15.  
    16. Sir,while solving the equations of motion, you mistakenly put the value of 2T in place of T.
    3 years ago by Aryan

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  16.  
    17. Sir, while solving the equations in the last step, you mistakenly added µ below N2.
    3 years ago by Aryan

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  17.  
    18. sir unable to solve the question sets
    3 years ago by

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  18.  
    19. Sir I have doubt from your book, sir please can you explain pg. 119 , Illustration ex. 2.49
    3 years ago by Amarnath boro

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  19.  
    20. Why isn't mg added in the downward direction of the FBD of B before string 1 snaps?
    3 years ago by Lucky Singh

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  20.  
    21. Sir, the strings are different then how did you apply virtual work theorem?
    3 years ago by Lucky Singh

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  21.  
    22. When there is no relative motion between block 1 and 3 and 2 and 3, why will friction act on the blocks 1 and 2?
    3 years ago by Lucky Singh

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  22.  
    23. Sir, during ascension the final velocity is zero and the initial velocity is not zero. I couldn't understand how did you take the time of ascension to be (2l/a)^0.5. Please elaborate sir.
    3 years ago by Lucky Singh

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  23.  
    24. Though the bigger block is accelerating, the block B is at rest with respect to it. Then why is there a need to bring pseudo force into picture?
    3 years ago by Lucky Singh

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  24.  
    25. Sir, in first question, in the FBD of block of mass M1 you drew the components of N3 (N3costheta and N3sintheta) as well the whole N3 itself and same in M2 (the rod). Is it compulsory to draw all three of them together or we can draw only the components of the force N3? This is because if I add N3costheta and N3sintheta I will get twice of N3. Kindly answer sir.
    4 years ago by Avinash Kashyap Jha

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  25.  
    26. Why T< g/4 if a > g/4 sir?? Please explain sir
    4 years ago by

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  26.  
    27. Sir speed changing option should be added to video player
    4 years ago by Jakaria Ahmed
    Ans 1 ->
    it is already there just click on setting in bottom right corner and click on playback speed and then select the speed u want....
    4 years ago by

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  27.  
    28. why dont the accln of block(a+c)=a
    4 years ago by Ayush Agarwal

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  28.  
    29. sir these video are 8 year old is these video are good for preparation of neet 2022.... I mean if some new topic are the some new tricks are added so I am asking is these all video are good for neet 2022
    4 years ago by Aryan Gouttam

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  29.  
    30. Sir how do we derive the expression: F= APV^2?
    4 years ago by Ragala Banu Prakash

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  30.  
    31. Sir , here in the example you said that body will bend in the direction of force whereas in the graph where Fsin(theta) which is responsible for changing the direction of the body , did not bend the body in it's direction . Why ?
    4 years ago by Mansi Sikarwar

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  31.  
    32. Sir, you said that tension always acts away from point of contact of string, then the tension developed in the string due to the force applied by the boy should be away from the direction of applied force. Why do you think the tension in the string is along the direction of applied force?
    4 years ago by Lucky Singh

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  32.  
    33. I didn't understand lami's theorm?
    4 years ago by Maddi sathvik

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  33.  
    34. Sir where is Fundamental classes like NLM where video is of approximate 45 min
    4 years ago by

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  34.  
    35. Sir, can we not consider the whole cabin along with the mass of man as a system because the man is standing inside the cabin? And after considering whole mass of cabin and man which comes out to be 120kg we can find the tension.
    4 years ago by Prateek Singh

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  35.  
    36. sir, my doubt is how f sin theta is positive in the free body diagram which you made at the end?
    4 years ago by Swapnil Acharya

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  36.  
    37. Sir it's awesome ???? helps me to revise concepts and make my preparation easier
    4 years ago by

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  37.  
    38. sir aap kabhi mera ques ko answer naikarte
    5 years ago by
    Ans 1 ->
    kabhi bhinai kartey
    5 years ago by

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  38.  
    39. sir when b will fall,will it fall in straight line or parbola provided gravity
    5 years ago by

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  39.  
    40. in a free body diagram is it important to show accelaration or velocity of blocks, as i have readed somewhere that in a FBD we have to only show forces acting on a system.
    5 years ago by Rohan yadav
    Ans 1 ->
    yes as force depends on mass and acc
    5 years ago by

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  40.  
    41. is it important that normal force will activate only when two bodies are pushing each other, will it activate when i am just touching an object?
    5 years ago by Rohan yadav
    Ans 1 ->
    if you touch the object and you feel the ground then normal force is actingbut in small quantity otherwise it can be negligible
    5 years ago by

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  41.  
    42. sir please help me, currently I am completely dependent on your lectures for physics as I am preparing for IIT JEE but i also want to read a textbook which book should I prefer between NCERT or HC VERMA for reading purpose.
    5 years ago by Rohan yadav
    Ans 1 ->
    Both the books are a must,Ncert builds your basic level(for which sir's lectures are also sufficient)then the theory pirtion can be read from hc verma which is concise and straightforward.For problem practice do the questions of Hc verma ,ncert ,sir's books and the solved examples and mcq tests on website.Hope it helps!
    5 years ago by Dakshesh Prasad
    Ans 2 ->
    if youre studying for jee main, then sir lectures plus ncert plus hc verma and dc pandey is enough but if you want t clear advanced then you are wasting time now , you should go to coaching as there its actually harder in fact of a new level . solve the previous year papres
    5 years ago by
    Ans 3 ->
    also for advanced you will needirodov or pathfinder level of books
    5 years ago by

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  42.  
    43. for chemistry from where we the students of pg group take lectures..please suggest sir
    5 years ago by Bibek Chaudhary

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  43.  
    44. sir please add concepts regarding combination and cutting of spring.please
    5 years ago by Bibek Chaudhary

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  44.  
    45. sir,In what conditions does pseudo force act along the motion of force applied?It is possible or not?
    5 years ago by BIBEK CHAUDHARY

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  45.  
    46. sir,in many questions calculation becomes very complex . how to solve them without using calculator?
    5 years ago by BIBEK CHAUDHARY

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  46.  
    47. sir,why we do not use principle of superposition in case of normal reaction force?
    5 years ago by BIBEK CHAUDHARY

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  47.  
    48. SIR I HAVE THE QUERY ON THE QUESTION SET 1 HOW TO GET THE SOLUTION PLEASE PROVIDE THE SOLUTION
    5 years ago by aryan agarwal

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  48.  
    49. how come a=gtantheta sir pls tell how
    5 years ago by Yash Veer Nagar

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  49.  
    50. sir u said 3rd law is not applicable in pseudo force but the boy on skateboard must be experiencing reaction force so with respect to him the block must also be experiencing a reaction force that is why only it will appear to move (the action reaction between ground and the block ) sir pls clarify thank you
    5 years ago by Yash Veer Nagar

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  50.  
    51. SIR in example 1 if system is at rest then what would be the value of N2 Will it be zero ? pls answer sir
    5 years ago by Yash Veer Nagar

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  51.  
    52. sir in FBD we have to show all forces acting on the body but mg is acted by the body on the ground so why have u shown mg in FBD
    5 years ago by Yash Veer Nagar
    Ans 1 ->
    we have to count a force as a force whether be it toward ground on not as it only balances the normal reaction,, suppose its in air so it wil fall freely since no ground so no normal, thats why we have to show both the forces
    5 years ago by

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  52.  
    53. Hello sir why forces are not transferred from one body to anthoer
    5 years ago by

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  53.  
    54. Respected Sir, In the second example where we've considered 2 blocks and a table, why we have taken accn of both the blocks same? In controversy to the 1st example where we've seen that both the blocks are moving with different accns connected to the spring..
    5 years ago by Pranavendra S Fauzdar

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  54.  
    55. Sir, if pseudo force comes in presence, how can we justify 3rd law of motion
    5 years ago by SCREENTUTOR

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  55.  
    56. in the last examples there are many pulleys connected to M but you have only accounted one downward tension why?
    6 years ago by Umair Hasan saifi
    Ans 1 ->
    because tension on the string depends on the'string' notnumber f pulleys provided that the there is no new string
    5 years ago by

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  56.  
    57. sir is the insect crawling up or moving down... this is a standard jee module wherein the insect moves up... so how does friction act upwards in this condition
    6 years ago by nazim

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  57.  
    58. Why is a2 relative to wedge?
    6 years ago by Subhradeep Mahata

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  58.  
    59. Sir if we make string in straight line then acceleration should be added but you have substracted.. I cant understand
    6 years ago by OMESH KUMAR

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  59.  
    60. Video is moving fast and words are getting late
    6 years ago by Suma Sikaram

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  60.  
    61. where will i find solutions of Qset ??
    6 years ago by mayank Pathak

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  61.  
    62. Sir, Why the system will not be in equlibrium at maximum displacement? before watching the video, i was trying that way
    6 years ago by Adarsh Mall

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  62.  
    63. Sir, Why will block A have the tendency to move rightwards?
    6 years ago by Adarsh Mall

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  63.  
    64. sir are the Allen modules and your lectures are enough for practice
    6 years ago by vanshika sharma

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  64.  
    65. Bird cage question:Assume that you are holding a cage containing a bird. Do you have to make less effort if the bird flies from its position in the cage and manages to stay in the middle without touching the walls of the cage? Does it make a difference whether the cage is completely closed or it has rods to let air pass?
    6 years ago by Chhavi Gupta

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  65.  
    66. how can both the acc.. be in downward direction
    6 years ago by Md Zakie Akhtar Ansari

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  66.  
    67. sir, in the second example when drawing FBD for M you haven't considered mg in downward direction .why?
    6 years ago by Sunny Kumar
    Ans 1 ->
    we can condsider it in down ward direction and sir has taken its components to solve the problem
    5 years ago by

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  67.  
    68. So,sir if we are assuming the direction of acceleration,then we have to take care of the direction of movement of other connected pullies also?As in the case of this question,for first block,direction is downward,then that of second block should be in upward direction and the third one again in downward direction?
    6 years ago by Manasi Singh

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  68.  
    69. How can we write T2=mu.mg?Please elaborate.
    6 years ago by Manasi Singh

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  69.  
    70. Sir,how is T3=W?Please explain!
    6 years ago by Manasi Singh

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  70.  
    71. Sir,'l' is the length of rod also and the distance by the rod also?Not able to understand,please explain!
    6 years ago by Manasi Singh
    Ans 1 ->
    *distance covered
    6 years ago by Manasi Singh

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  71.  
    72. For the rod of mass M,in the equation of motion i.e.,in the second equation,have you simply substituted 'f' in place of 'T'?Or you have used some other logic?
    6 years ago by Manasi Singh

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  72.  
    73. Sir,while writing the equations of motion,how do we consider which force is smaller and which one is larger?Is the bigger force in that direction in which the body is accelerating?
    6 years ago by Manasi Singh

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  73.  
    74. How can both the accelerations be in downward direction?
    6 years ago by Manasi Singh

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  74.  
    75. Is rod also coming down the string?Or is it moving along the string?
    6 years ago by Manasi Singh

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  75.  
    76. Why is there tension force down the bead?
    6 years ago by Manasi Singh

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  76.  
    77. what is the range of nuclear separation and what is small and large separation.
    6 years ago by shivani mishra

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  77.  
    78. Which lecture will contain torque??
    6 years ago by Siddhant Kothiya

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  78.  
    79. Namaste sir, In the above illustration,why shouldn't we consider the pseudo force on block of mass m? Can you also clarify when and when not to us the pseudo force concepts in pulley and wedge problems? Thank you in advance sir.... With Pranams
    6 years ago by Govinda Madhava.B.S

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  79.  
    80. Sir; Why we make normal force in an inclined plane as a component of mg i.e. mg cos(theta), BUT in problems of a car on banking road , we take normal force not component of( m x g ) but N cos (theta) = mx g. why it is so??
    6 years ago by Mahesh Yadav

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  80.  
    81. Sir, I have one question. How can i send you. I listened your lectures and very impressive.
    6 years ago by Palak Chawla

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  81.  
    82. Sir Why aren't you saying it Normal Action instead of Normal Reaction??
    6 years ago by J Mahender

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  82.  
    83. Why all forces acting on string to be zero??
    6 years ago by Vaasu Bisht
    Ans 1 ->
    because the resultant is zero
    6 years ago by saurabh

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  83.  
    84. thanks jii u r grt
    6 years ago by prabhsimran singh
    Ans 1 ->
    YA
    5 years ago by

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  84.  
    85. How you integrated (v0 e^-rt/m) to Go/rt1(-e^rt/m)??
    7 years ago by Sandal Agarwal

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  85.  
    86. if the spring applies the force 'Fr'(restoring force) in the wall also at left end of spring . do the man will also apply same force Fr on spring in opposite direction ?
    7 years ago by

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  86.  
    87. i need help from you.. should i see advanced illustrations just after the concept videos or after completing all chapters concept videos??what are your views??please help fast
    7 years ago by Sandal Agarwal

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  87.  
    88. in which video virtual work concept has been covered??(as said by sir in the video)(and why did you took sum of T as 0)
    7 years ago by Sandal Agarwal

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  88.  
    89. How did u found out the angle as theta
    7 years ago by Dharini

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  89.  
    90. sir if an observer accelerates towards right with an acceleration(a) and watches an object at rest w.r.t ground, then the acceleration of the object will be (a) towards left so why it would not be (-a), that is the acceleration of the object w.r.t. observer, hope your reply soon.
    7 years ago by Siddharth Maurya
    Ans 1 ->
    already 3 months
    7 years ago by Kranti Veer Nagar
    Ans 2 ->
    watch vedio from 2:32 to 2:44.....u will get ur ans..
    6 years ago by vanshika deval

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  90.  
    91. A block is kept on a smooth inclined plane of angle of inclination theta that moves with a constant acceleration so that the block does not slide relative to the incline plane if the incline plane stops the normal contact force offered by the plane on the block changes by a factor?
    7 years ago by Avinab Neogy

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  91.  
    92. sir if I see your lecture properly then can i get rank under 8000 ?
    7 years ago by Vikas kumar

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  92.  
    93. in the last example the 20kg block will move with acceleration of 4a because the 80 kg bloack is connected to both strings so there will be the effect of the second string also on the 20kg block
    7 years ago by rohit

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  93.  
    94. sir will the tension change if the spring balance will have mass ?
    7 years ago by rohit
    Ans 1 ->
    yup
    5 years ago by

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  94.  
    95. sir, the mass of the wedge is more than the rod then how will the horizontal component of N will produce a acceleration 'a' so tht the wedge will move?
    7 years ago by rohit
    Ans 1 ->
    haan bhai friction nahi hai, dot visualize here, visualization is a trap in motion without friction
    5 years ago by

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  95.  
    96. sir, as pseudo forces do not obey newtons laws ,why should we include it in the free body diagram of a body?
    7 years ago by eshwar

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  96.  
    97. Sir what happens when the elevator will come down with an acceleration equals to acceleration due to gravity.
    7 years ago by Ajit pal
    Ans 1 ->
    When a elevator moves with acc g then normal force on body=m(g-g) becomes zero hence person in lift is in the situation weightlessness.
    7 years ago by Manoj Jajoria
    Ans 2 ->
    then vertically everything will get balanced. and youll float like in space
    5 years ago by

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  97.  
    98. WHY DO WE TAKE THE CONSTRAINED MOTION EQUATION AS a1=a tan(tetha). WHY IS IT TAN (THETHA)?????
    7 years ago by Christina Pereira
    Ans 1 ->
    sir, the mass of the wedge is more than the rod then how will the horizontal component of N will produce a acceleration 'a' so tht the wedge will move?
    7 years ago by rohit

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  98.  
    99. Sir, how do we come to know which component to mark as N3sin() and N3cos(). Do we always mark horizontal component as N3sin()????
    7 years ago by Christina Pereira

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  99.  
    100. sir if a body of mass m is initially at rest . a periodic force F=a cos (bt c) is applied to it, where a,b,c are constant. so the smallest value of t after t=0 when the velocity of the body becomes zero is given by...? sir i am getting my answer (-c/b) or (p-c)/b and so on.. but correct answer is p/b.... where i am wrong ..... #Help
    7 years ago by Ashutosh jaiswal

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  100.  
    101. Sir due sidewalls friction should be 2f??????
    7 years ago by Rakesh singh

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  101.  
    102. Very nice explanation thank you sir.
    7 years ago by HEMANT KUMAR DHAKA

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  102.  
    103. If block A moves up with "a (upwards)" acceleration then, according to constraint relations, acceleration of block B should be "2a (downwards)" . But we had taken acceleration of block B as zero. why??
    7 years ago by Anmol Mishra

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  103.  
    104. Does the system remains at rest??? Why??
    7 years ago by Anmol Mishra

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  104.  
    105. sir, y=3x right? so a2=3a1..plzzz.help me......
    7 years ago by GEETHU MOHAN
    Ans 1 ->
    no y= 2x
    5 years ago by

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  105.  
    106. In the previous problem you had done that just after string snaps the tension changes and you took it as T ' why in this problem it is taken that the tension does not change and remains same due to inertia? Please reply sir Thanks
    7 years ago by Harish D

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  106.  
    107. sir I take that string is just attached to rod at one end then for acceleration of rod friction will not be coming into picture and it is not mentioned in the question as well. Sir I just want to say how I thought immediately after seeing question and I understand your solution sir.
    7 years ago by dinesh sai

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  107.  
    108. sir the acceleration here should be 40/25 not 2m per second square. if I am not correct then please tell me.
    7 years ago by keshav Maheshwari
    Ans 1 ->
    Here both the blocks are not moving together so he consider both separately only... and using their FBD he find their accelerations...
    6 years ago by vanshika deval

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  108.  
    109. sir earth is also accelerating around the sun with an acceleration of 0.005928 meters per second squared.,so how could we consider the ground to be at inertial frame
    8 years ago by arunima@gmail.com
    Ans 1 ->
    Great question
    6 years ago by Tanmay Goyal
    Ans 2 ->
    As u can see....acceleration of earth is very low so we neglect it in general cases and consider earth as an inertial reference frame.
    6 years ago by vanshika deval

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  109.  
    110. Sir here shouldn't the acceleration of mass m be 2a
    8 years ago by keshav Maheshwari

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  110.  
    111. Sir if an observer is moving with constant velocity (zero acceleration) will his frame of reference be inertial or non inertial?
    8 years ago by APARIMIT KASLIWAL
    Ans 1 ->
    the frame of reference will be non inertial
    8 years ago by Abhinav kumar Yadav
    Ans 2 ->
    it will be inertial, as acceleration is zero with respect to ground
    6 years ago by vanshika deval

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  111.  
    112. sir wont the normal reaction of the ground balance the weight of block of mass m? if taking this into account the resultant force on m mass will be Tension only?
    8 years ago by rishabh bhatnagar

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  112.  
    113. Sir some of my answers of Qset are not matching with the answers given... how could I clarify them? Is there any solution set? Are the given answers are for sure ? Please say the way sir.
    8 years ago by dinesh sai

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  113.  
    114. Sir won't there be a pseudo force on A due to B being an accelerating frame?
    8 years ago by Mahaksh Kanhaiyalal Trivedi

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  114.  
    115. Respected sir Since the block is being launched it must have an initial velocity u. But this fact is ignored in the solution...
    8 years ago by APARIMIT KASLIWAL

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  115.  
    116. Respected sir why will the friction be mu mg and mu 2mg in a+c and b block systems respectively?
    8 years ago by APARIMIT KASLIWAL
    Ans 1 ->
    because value of kinetic friction is mu * normal reaction and as there is no vertical motion n = weight of the object
    8 years ago by Prateek Kumar

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  116.  
    117. what basics the newtons laws are verified
    8 years ago by Amarnath.P

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  117.  
    118. why work done by tension is considerd as zero
    8 years ago by M NAGARAJU
    Ans 1 ->
    Net Work done by tension force is considered to be zero because this is an internal force and we know that only eternal force is reponsible for work. You will lean this concept by watching the next video archive
    8 years ago by Abhinav kumar Yadav

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  118.  
    119. Sir is the application of moments in solving newtons law problems covered? Because in the worked examples of my book many problems they have used net moment about a point is 0 but we have not learnt finding moments yet.
    8 years ago by Harish D
    Ans 1 ->
    bro, don check out the solutions first. try to solve the questions by yourself after watching these videos as these are more than enough to solve toughest of the tough problems. ASHISH ARORA sir is the best physics teacher I have ever seen.
    8 years ago by sujith kumar

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  119.  
    120. Could you please provide proof for the virtual work method? Thanks.
    8 years ago by Swapnil Das
    Ans 1 ->
    This is the shortest way of solving such questions... if you solve by observation, it will take more time in analyzing such constrained relations...
    8 years ago by sujith kumar

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  120.  
    121. why you are taking the breaking strength of the rope as the tension in the string sir????????
    8 years ago by ashish
    Ans 1 ->
    here, as we have to find the acceleration of the sliding boy under the condition that the rope does not break hence we must take the value of tension as the maximum value before the rope snaps.
    7 years ago by Ashwin Murali

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  121.  
    122. when pulley have a finite mass and radius then how to find torque and in which section you have explained it sir
    8 years ago by sagar

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  122.  
    123. sir how that angle is taken thita?
    8 years ago by Ved Singh

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  123.  
    124. sir why not perpendicular force can change the magnitude of velocity?
    8 years ago by Mani Kanta Chalamalla
    Ans 1 ->
    even i hav the same doubt
    7 years ago by Prakash Raj
    Ans 2 ->
    BECAUSE ITS PERPENDICULAR COMPONENT IS 0 SICNCE VCOS90 =V*0=0
    5 years ago by

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  124.  
    125. Sir is any more easy way to do this or its compulsory to solve equations even in the exam??If this is then how solve these equations more quickly??
    8 years ago by Advait Kulkarni
    Ans 1 ->
    This is the shortest way of solving such questions... if you solve by observation, it will take more time in analyzing such constrained relations...
    8 years ago by Physics Galaxy

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  125.  
    126. sir why you did not added normal reaction in the fbd of B
    8 years ago by Amrender Singh

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  126.  
    127. when a thread is hinged at the top of a car and the and is outside of the car the other end is tied to a block of mass m then what are the forces acting on the block can the block will acclerate or not
    8 years ago by hemanthsai

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  127.  
    128. Sir may i know in how much time we can complete the entire physics course by watching videos and solving questions from various illustrations given. I need to plan my studies.
    8 years ago by Poonam Jain
    Ans 1 ->
    it will take maximum of 5 months and minimum 3 months if you plan it regularly and practice consistently...
    8 years ago by Physics Galaxy

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  128.  
    129. My question is the same as the one indicated by the following link to a webpage: http://www.meritnation.com/ask-answer/question/find-the-accelerations-of-the-two-blocks-and-the-tension-on/laws-of-motion/10713153 Also, if the tensions would be the same for a single rope, then the tension in D must be the same as the tension in the opposite two segments.... but by the laws, T at D must be twice that of T at the opposite arms.
    8 years ago by PSai Krishna Kvmb
    Ans 1 ->
    I didn't know how to upload an image, so I sent a link.
    8 years ago by PSai Krishna Kvmb
    Ans 2 ->
    T=2T when T=0 thats what happens here... If in this case all pulley and strings are light, the string will become slack and bodies will be in freefall...
    8 years ago by Physics Galaxy
    Ans 3 ->
    Sir, by T=2T implying T=0, I understand that for the pulleys, we considered T at C, F and E to be T, then we conclude T at D ang G is 2T due to the constraints... but for ideal case, T at D must be T as everywhere else it is T on the rope... so, T = 2T or, T=0. Thus, T at G is 2*0 = 0. I agree to this. However, I do not agree that the bodies will be under free fall for eternity. This is because, the blocks would have to move down with acceleration g. However, my intuition says, the accelerations of the blocks if non zero, must be opposite in directions. However, the upward acceleration would have been possible due to a presense of a tension. But, we have proved that T=0 without considering where the blocks are... i.e., this is a general condition, so, T must always be 0. Then I say to mysely... they must be under free fall... then I point out to myself... the blocks have to move oppositely... then I say to myself... for the upward acceleration, tension must be present... then I remember... T=0.... Sir, this is a mess sir... plz help... as you can see... I am currently envisioning a vicious circle without an exit... where am I going wrong? I have been thinking about this for 3 days... but haven't come to a good conclusion. When you showed T=0, that was a ray of hope.... but now that is proven... I have entered the vicious circle... But, I thank you for proving T=0 sir.... I didn't think of that situation... but, please point out my mistake sir...
    8 years ago by PSai Krishna Kvmb

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  129.  
    130. If the 2m mass moves forward by x distance the string will need 2x length that will come if mass m moves by 2x distance. Means a(2m) = 2*a(m). Isn't it?
    8 years ago by Ankit Shukla
    Ans 1 ->
    If 2m moves to the right by x as string length is constant m can only move to left by x... what you have written is possible only if string can elongate... mass of m with respect to 2m will be twice as both are moving in opposite direction...
    8 years ago by Physics Galaxy

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  130.  
    131. sir where have u explained torque
    8 years ago by Shardul
    Ans 1 ->
    Section of torque is under the topic of Rigid Body dianamics but the videos will be active by coming weekend...
    8 years ago by Physics Galaxy

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  131.  
    132. sir do we want to integrate in second case as it is just average velocity (can't we simply add final and initial velocity and divide by time)
    8 years ago by Sankar Nampoothiri KM
    Ans 1 ->
    No... as (v-u)/t will give you average acceleration not the average velocity and here average velocity cannot be obtained directly as its not a linear variation with time...
    8 years ago by Physics Galaxy

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  132.  
    133. Can I add images to my questions??
    8 years ago by Devansh Agrawal
    Ans 1 ->
    Not now... but its in plan in first half of 2017 we will launch the system where you can post question with image here in INTERACT tab...
    8 years ago by Physics Galaxy
    Ans 2 ->
    Then physicists would be everywhere!
    8 years ago by PSai Krishna Kvmb

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  133.  
    134. Velocity of the river with respect to the ground is given by V. Width of the river is d. A swimmer swims ( with respect to water) perpendicular to the current with acceleration a=2t (where t is time) starting from rest from the origin O at t=0. Find the time of crossing the river and drift of the swimmer.
    8 years ago by Devansh Agrawal

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  134.  
    135. SIR THIS LECTURE IS SOMEWHAT DIFFICULT TO UNDERSTAND. PLEASE FIND ANY ALTERNATIVE FOR EXPLAINATION
    8 years ago by KAIKALA RAVI KUMAR

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  135.  
    136. In the constraint motion example...Why are we assuming that m1 goes up and m2 goes down? nowhere has it been mentioned that m2 greater than m1. Plz clarify.
    8 years ago by Ahan Karmakar
    Ans 1 ->
    It has just been assumed. If your answer comes out to be negative then it means you need to take the opposite direction. See the constrained motion topic for more details.
    6 years ago by Varsneya Srinivas

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  136.  
    137. In the constraint motion example...Why are we assuming that m1 goes up and m2 goes down? nowhere has it been mentioned that m2m1. Plz clarify.
    8 years ago by Ahan Karmakar
    Ans 1 ->
    it has not also been given which is m1 and m2 all is starting with 'supose'
    5 years ago by

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  137.  
    138. SIR HOW FRICTION ACTING ON STRING IS DOWNWARD AND HOW IS IT EQUAL TO TENSION
    8 years ago by KAIKALA RAVI KUMAR
    Ans 1 ->
    do not think that bead is hung on the string as bead is free to slide on the string as friction on bead acts upward due to sting same friction acts downward on sting due to bead and as sting is mass less the two forces acting on string will be same
    8 years ago by Prateek Kumar

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  138.  
    139. Sir,can you explain spring force
    8 years ago by TANMAY chhabra

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  139.  
    140. Q)The end links of a uniform chain slide along a fixed rough horizontal rod. Prove that the ratio of the maximum span to the length of the chain is clog[1/c+sqrt(1+c^2)/c]where c is the coeff of friction?Can anyone solve this please?
    9 years ago by Akshay Ft Snoopdogg

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  140.  
    141. sir why should not we take kysin(theta)=T (Tension in thew string)
    9 years ago by saikiran

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  141.  
    142. Sir in the FBD of m1 friction force f is acting towards right.So how can man remain at rest.Please explain
    9 years ago by Udit gupta
    Ans 1 ->
    This f remain zero till man is at rest, it will appear only when plank starts sliding along with man...
    9 years ago by Physics Galaxy

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  142.  
    143. Sir if we take tension T in small string why the answer is different??
    9 years ago by Vivek Singh
    Ans 1 ->
    Sorry sir,It was calcu. mistake....
    9 years ago by Vivek Singh
    Ans 2 ->
    Answer remain same in all cases, it will not change as far as the solution is with proper concepts and correct method.
    9 years ago by Physics Galaxy

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  143.  
    144. If Newton's laws is applicable for large bodies then how come it be applicable for particles
    9 years ago by johnsen
    Ans 1 ->
    Newton's laws are applicable for all bodies which have inertia and for massless particles as inertia is zero no significance of NL are there...
    9 years ago by Physics Galaxy

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  144.  
    145. sir here two cases can be made one when bigger block moves toward right and other when it moves toward left ?
    9 years ago by Manav kapur

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  145.  
    146. sir if we calculate the accn of block b wrt to ground can we take the fbd of inertial frame ?
    9 years ago by Manav kapur

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  146.  
    147. actually i am asking how friction on string is in downward direction
    9 years ago by Manav kapur

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  147.  
    148. sir please tell how friction is equal to tension i am not getting it !
    9 years ago by Manav kapur

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  148.  
    149. sir why normal force and weight are not considered to be action-reaction pair?
    9 years ago by R Rohit
    Ans 1 ->
    action reaction force always act on different bodies but here we talking about single body and all the forces that acting on it only
    9 years ago by Harpreet Kaur
    Ans 2 ->
    AND ONE MORE REASON FOR ACTION- REACTION PAIR FORCES MUST BE OF SAME KIND. MG AND N ARE TWO DIFFERENT TYPES OF FORCES ONE IS GRAVITAIONAL FORCE AND OTHER IS CONTACT FORCE.
    7 years ago by RAHUL KUNTAL

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  149.  
    150. Sir please could u give the solutions of QUset ?? it will be very helpful
    9 years ago by LAIBA NOOR
    Ans 1 ->
    No
    9 years ago by Neeraj Tembhe

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  150.  
    151. sir in the first example suppose we hang two different mass of blocks on either side of the spring then what will happen.
    9 years ago by sagar choudhury

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  151.  
    152. Sir. Does action occur prior to reaction?
    9 years ago by Riyank arora
    Ans 1 ->
    no action and reaction occur simultaneously don't believe check out ncert
    9 years ago by johnsen
    Ans 2 ->
    PRACTICALLY THERE ALWAYS IS A REACTION TIME ....... ITS IN NANOSECONDS THAT CAN BE COUNTED NEGLIGIBLE FOR NOW
    5 years ago by

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  152.  
    153. please tell fast
    9 years ago by sagar choudhury

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  153.  
    154. how normal reaction and tension in a string are electromagnetic in nature
    9 years ago by sagar choudhury

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  154.  
    155. When we consider a freely falling body there is weight(gravitational force) acting on it. In this case what is the reactional force on the body?
    9 years ago by Rakshith Aloori

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  155.  
    156. Sir, in the second video of Newton's Law of Motion, you have said that a normal force changes direction of velocity only. But how come the magnitude of velocity doesn't change when force is applied when there is some acceleration in y-axis direction(along the direction of force)?
    9 years ago by Rakshith Aloori

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  156.  
    157. sir why should there be different tensions at different points?
    9 years ago by Ajay Sabarish

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  157.  
    158. sir iam getting a different answer upon solving those 3 equations
    9 years ago by Ajay Sabarish
    Ans 1 ->
    Its because sir wrote T=3mg by mistake [its 2T=3mg]
    8 years ago by deependra kapoor
    Ans 2 ->
    *3ma
    8 years ago by deependra kapoor

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  158.  
    159. can you also explain the constraint relation by relating the positions
    9 years ago by Ajay Sabarish

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  159.  
    160. sir can you please explain how you got the constraint equation
    9 years ago by Ajay Sabarish
    Ans 1 ->
    no where constraint relations has been used here...it is simply written by observation
    8 years ago by Irshad Ahmed Khan

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  160.  
    161. why here acceleration is negative? please respond sir.
    9 years ago by surya
    Ans 1 ->
    accn is bcoz of resstoring force ! it decreases the velocity of bullet with time
    9 years ago by Manav kapur

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  161.  
    162. why should the blocks move together sir?
    9 years ago by Ajay Sabarish

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  162.  
    163. sir there is also a force in vertical component won't it produce it's own acceleration in vertical direction?
    9 years ago by Ajay Sabarish
    Ans 1 ->
    assume it that mg is greater than fsin@
    8 years ago by Sankar Nampoothiri KM

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  163.  
    164. Sir,the last question of your booster class in which you associated acceleration with a massless pulley. Sir is it correct to say that a massless object has an acceleration, F=MA is'nt holding in that case! Please Explain!!
    9 years ago by Mehul Rawat

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  164.  
    165. sir is the wedge constraint relation a(wedge)=a(block)*cos(theta) valid?
    9 years ago by Ajay Sabarish

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  165.  
    166. sir there are some questions in quset 1 which are not ryt according to me.....there are some questions whose options donot match with the questions...and there are many other flaws i have noticed..plz make a check of it..it is a request to u..and sir may i get he solutions of these questions from somewhere? plz reply as soon as possible... :)
    9 years ago by Khushboo Jain
    Ans 1 ->
    no. we have to keep on trying until we get the answer.
    9 years ago by sagar choudhury

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  166.  
    167. do you have any site for chemistry which provides free videos like this site??????
    9 years ago by Tanay Gawade
    Ans 1 ->
    yes there are so many what i recommend you(that i use personaly) is www.ilectureonline.com and for organic chemistry you can check ajnish guptas you tube channel
    9 years ago by Harpreet Kaur

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  167.  
    168. Sir i have two questions 1) when a mass is suspended by a string attached to the string the mass is acted upon by mg and thus it tries to move downwards now it being attached to the string tries to make the string move along with it , but the string attached to the ceiling cannot move down with it and so to resist any change in its length it imparts a force T (tension) on the mass , now what i don't understand is what is the reaction of this tension which is created by the mass . secondly i have a doubt regarding a monkey rope problem , Sir i am unable to know understand the fact that when the monkey pulls down the string by a force F , then what is the the tension in the string , is it T= mg + f or T=f , and if it is T=f then sir where did the force acting on the string due to the block's mass m go ??? Sir please help
    9 years ago by Kushagr Tyagi

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  168.  
    169. Sir wen I solve the eq which u gave to solve in this lecture I got 2gsin¢/(7+4cos¢)
    9 years ago by sachin

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  169.  
    170. Der are glitches in the videos sir please check it sir!!
    9 years ago by sachin

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  170.  
    171. Can we use work done by the string =o in this sum
    9 years ago by sachin
    Ans 1 ->
    The video is slower than ur speech sir please check it sir ? Can't concentrate on the video
    9 years ago by sachin
    Ans 2 ->
    sir can you please derive the constraint equation using virtual work done method
    9 years ago by Ajay Sabarish
    Ans 3 ->
    HOW ACCELERATION OF A IS 2 TIMES THAT OF BLOCK B ACCELERATION
    8 years ago by KAIKALA RAVI KUMAR

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  171.  
    172. why pseudo force on m block is not taken into consediration?
    9 years ago by aashu gupta

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  172.  
    173. why did u not cnsider the component of tension Tcos0 along with 2T for A so that 2a(A) + cos0a(A) = a(B) ? plz reply !
    9 years ago by vishwanath v pai
    Ans 1 ->
    Yes I agree
    9 years ago by VAIBHAV GUPTA
    Ans 2 ->
    i also agree
    9 years ago by Rumeet Bir

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  173.  
    174. Sir, in case of a ball suspended from ceiling and pulled aside by an angle A with the vertical by application of a force F in horizontal direction we always equate TcosA = mg but not T= mg cosA... why???
    9 years ago by Kalvacharla Sasank

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  174.  
    175. How B will have same acceleration a upward ?
    10 years ago by Sushabh Deshmukh

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  175.  
    176. Sir why didn't you apply N1 on block ???
    10 years ago by Sushabh Deshmukh

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  176.  
    177. How did u write acc of mass B along plane = 2a ???
    10 years ago by Sushabh Deshmukh
    Ans 1 ->
    Use work done by all strings is 0 den u will get the relation
    9 years ago by sachin

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  177.  
    178. sir after cutting string 1 tension in string 2 shouldnt change should it/
    10 years ago by PRABAL
    Ans 1 ->
    Sa.e doubt here...just see the next problem...it has used what we were thinking
    8 years ago by Irshad Ahmed Khan

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  178.  
    179. Sir here shouldnt the acceleration of mass m be 2a ?
    10 years ago by PRABAL
    Ans 1 ->
    no bcos on m only 1T is acting and on 2m also only 1T is acting
    9 years ago by srinivas
    Ans 2 ->
    why pseudo force on m block is not taken into consediration?
    9 years ago by aashu gupta

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  179.  
    180. In the 2nd ex : hw can the accelertn of the blocks b equal wen it is connected through an extensible material like a spring ?
    10 years ago by vishwanath v pai
    Ans 1 ->
    In the question it is given that the accn. is uniform...
    9 years ago by Kumar Sambhav

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  180.  
    181. how do we get to know that after increasing acceleration body will have a tendency to go in which direction?
    10 years ago by rajat puri

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  181.  
    182. can we also use virtual work tehcnique i mean summation t.a=0 method for finding the constraint relation for the above question
    10 years ago by rajat puri
    Ans 1 ->
    Yes you can... in this case...
    10 years ago by Physics Galaxy
    Ans 2 ->
    how to use virtual work method please tell me sunil kumar
    9 years ago by akanksh

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  182.  
    183. if acceleration of m is to be determined then do we will take resultant of a1 and a2 ????
    10 years ago by rajat puri
    Ans 1 ->
    Yes.. because acceleration of m is considered relative to wedge so its net acceleration will be resultant of both...
    10 years ago by Physics Galaxy

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  183.  
    184. why did we multiply the tensions and the accns
    10 years ago by Ratnesh Phadke
    Ans 1 ->
    We are considering the work done by tension on all blocks equal to zero i.e. sum(T.s)=0 and on differentiating twice we get the relation sum(T.a) =0
    10 years ago by Physics Galaxy

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  184.  
    185. I looked at it again, and I forgot to consider the effect of tension on the pulley in the fbd of the large block. Sorry to trouble you.
    10 years ago by Paul Moore
    Ans 1 ->
    Ok...
    10 years ago by Physics Galaxy

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  185.  
    186. Solved example 6: I found this example to be very useful. I am confused as to why the required force on the large block is F = a(7m).= a(4m + 2m + m). The fbd for the large block does not have any interaction with block A (mass m) in the horizontal direction. I found that the force on the large block should be F = a (4m + 2m). Is this correct? I looked up this example when trying to solve the situation when the two smaller blocks are accelerating relative to the large block, and I do not see how the three blocks can be considered together even when the relative acceleration is zero. The interpretation that the system can be taken as a whole seems to ignore the fact that the force of gravity is also acting on block B and, importantly, via tension on block A. Please let me know where I am going wrong here. Thanks, for your really useful website.
    10 years ago by Paul Moore
    Ans 1 ->
    Pl watch video carefully again...
    10 years ago by Physics Galaxy

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  186.  
    187. i think a1=2a2.please explain.
    10 years ago by himanshu chhabra
    Ans 1 ->
    No here a2 = 2a1 as when block A slides by x due to this pulley also slides down by x and block B will go down by 2x...
    10 years ago by Physics Galaxy
    Ans 2 ->
    A simple way to remember...... The ratio of Tensions is the string connecting two bodies is inversely proportional to their accelerations.....
    9 years ago by Krishna Raajan

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  187.  
    188. Reference frame of Earth should be non inertial. This is because its accelerating. Am I correct?
    10 years ago by Ninad Akolekar
    Ans 1 ->
    You are right but as acceleration of earth is very low so we neglect it in general cases and consider earth as an inertial reference frame.
    10 years ago by Physics Galaxy

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  188.  
    189. We discussed Inertial and Non-inertial reference frames. However, I did not understand that velocity/acc. of these frames in their definition are relative to what? Frames with nonzero acc. are non inertial. but this nonzero acc. is relative to what??
    10 years ago by Ninad Akolekar
    Ans 1 ->
    non inertial frame is considered one which has acceleration with respect to an inertial frame and generally all inertial frame are considered to have zero acceleration with respect to ground (earth)...
    10 years ago by Physics Galaxy

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  189.  
    190. does pulley not exert force on string
    10 years ago by divanshu gupta
    Ans 1 ->
    When a string passes over a pulley... tension acts on pulley along the length of string...
    10 years ago by Physics Galaxy
    Ans 2 ->
    sir in the first example suppose we hang two different mass of blocks on either side of the spring then what will happen.
    9 years ago by sagar choudhury

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