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

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  1.  
    2. but how is it directly proportional to product of masses why it is not proportional of each mass
    3 months ago by om shelke

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  2.  
    3. Sir why is yt channel and website not working
    1 years ago by Palash Bairagi

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  3.  
    4. sir the answer is coming root of GM/R and not root of 2GM/R
    1 years ago by

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  4.  
    5. At the last, Sir mistakenly wrote wrong expression for Va.
    2 years ago by Utsab Majumder

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  5.  
    6. dFsintheta gets cancelled, and the forces should add and sum upto 2dFcostheta... Then the net force should be the integral of 2dFCostheta.. But in the video it shows dFcostheta ... then what about dFsintheta??
    3 years ago by

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  6.  
    7. how the vector df=-gm2dm/r3*R->
    3 years ago by

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  7.  
    8. thanks
    3 years ago by Pradumn Singh

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  8.  
    9. Sir, may I know as to how the the surface area is directly proportional to the square of x1 and x2 ? Thank You.
    3 years ago by

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  9.  
    10. why is base considerd as l at last step it should be smaller then l?
    3 years ago by himanshu

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  10.  
    11. sir audio nahi aa rha
    4 years ago by Abhishek Singh

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  11.  
    12. sir i did not understand anything
    5 years ago by Anshul Goel

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  12.  
    13. very nice thank u
    6 years ago by undefined

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  13.  
    14. sir in module no7 why did you take limit from -pi/4 to pi/4 and not 0 to pi/2
    6 years ago by Shubham pathak

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  14.  
    15. solutions of unsolved numerical problems for preparation of NSEP, INPho and IPho
    6 years ago by Anugrah Shrivastava

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  15.  
    16. how mutual attraction is coming is 2r^2
    6 years ago by anujit das

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  16.  
    17. Sir how can we get the solutions of the Qusets.
    6 years ago by Bighnesh Sahoo

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  17.  
    18. I think there are a few wrong answers in the gravitation question set 1
    6 years ago by Anubhav Mahapatra

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  18.  
    19. plZ tell the method to take the appropriate limits
    7 years ago by vijay hans

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  19.  
    20. I think the final answer should have R^2 in the denominator
    7 years ago by

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  20.  
    21. Sir physics ki best numerical book koun si jo jee ke liye Achi ho
    7 years ago by Avinash Pandey

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  21.  
    22. Will G remain same wherever we go ?
    7 years ago by Roy Ankush Sanjay
    Ans 1 ->
    yes
    7 years ago by Sonu Raj

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  22.  
    23. In HC Verma book they say, V is equal to change in potential energy per unit mass, as mass is brought from infinity to reference point. And the change in potential energy is -W, so why dw=dm(V) why not dw=dm(-V)?
    7 years ago by Ayush Jaiswal

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  23.  
    24. sir i didnt understood defination of gravitational field strength plz write here clearly again
    7 years ago by Dharamjeet Singh

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  24.  
    25. Good
    7 years ago by Ranjit Kumar lahiri

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  25.  
    26. sir, what if the point is on the thread/cylinder...r will be zero...will the field strength be infinity?
    7 years ago by Vivan Maurya

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  26.  
    27. gravitation Quset 3 question no 24 all answer incorrect plz answer
    7 years ago by narayan kalani

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  27.  
    28. fcos() is considered
    7 years ago by vikas

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  28.  
    29. sir,why we have taken the limits as -pi/4 to pi/4
    7 years ago by Rahul Jaiswal

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  29.  
    30. why have we taken the limits of integration from -45 to 45. cant we take them from 0 to 90. also is it necessary to take two components of force. isn't there a better method to solve it?
    7 years ago by sans

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  30.  
    31. How did the denominator change in last step. From where was the minus sign multiplied.
    8 years ago by Kaanapuli RamKumar
    Ans 1 ->
    while taking Re from lhs to rhs and taking lcm the change can be observed
    7 years ago by

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  31.  
    32. Sir can you please post the solutions for the QuSet 1 which you gave.. i couldnt solve some questions so i need your help to solve them....can you help me with the solns.
    8 years ago by Sriram Narayanan

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  32.  
    33. Do average density of earth depend on 'g' ?
    8 years ago by Yashraj Labde

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  33.  
    34. Why is d(m)=m/90*d(theeta) ?
    8 years ago by Yukti Khosla
    Ans 1 ->
    Because the mass distribution is constant and is distributed over and angle pie/2 so the mass of elemental part is that .
    8 years ago by GIRI NATH

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  34.  
    35. Where did the neagtive sign go in the last step?
    8 years ago by Yukti Khosla

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  35.  
    36. SIR WHERE CAN I SEE RECORDED LECTURES OF BOOSTER CLASSES?
    8 years ago by amit mittal

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  36.  
    37. How did we got the expression for the dm?
    8 years ago by Akshunn Trivedi

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  37.  
    38. Shouldn't it be V is equal to g DX as 1 negative due to force in opposite direction and another negative due to DX decreasing hence V is equal to positive g DX
    8 years ago by Divya r
    Ans 1 ->
    watch it carefully... we are analyzing its vector form...
    8 years ago by Physics Galaxy

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  38.  
    39. Sir there is no derivation for a long cylinder
    8 years ago by Akshunn Trivedi
    Ans 1 ->
    its similar to that of a long uniformly charged thread... already discussed...
    8 years ago by Physics Galaxy

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  39.  
    40. Sir it is a long thread not a long cylinder pls change the title!!
    8 years ago by Akshunn Trivedi
    Ans 1 ->
    both results are same and physically thread can be taken like a cylinder of small radius... this result will also be same for outer points of a cylinder...
    8 years ago by Physics Galaxy

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  40.  
    41. why is the grav. field due to sphere(after making cavity) at pt. P along the dirn of l(v)..we got y(v)-x(v)= -l(v)..so is it not opp. to dirn of l(v)?? [v-vector]
    8 years ago by

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  41.  
    42. SIR WHAT IS THE DIFFERENCE BETWEEN SOLID AND HOLLOW SPHERES. CAN U GIVE ME ONE EXAMPLE
    8 years ago by KAIKALA RAVI KUMAR
    Ans 1 ->
    Hollow sphere is empty inside and has zero field inside and solid is filled with the material of uniform density inside...
    8 years ago by Physics Galaxy

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  42.  
    43. why did we have to take components of dF? why could we not intgate dF directly from 0 to pi/2??
    9 years ago by sezal
    Ans 1 ->
    Because the Gravitational force acting on mass m is not constant throughout the quadrant(ring) because of its changing shape.(Or the gravitational force acting on the point is not in just one direction)
    8 years ago by Akshunn Trivedi

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  43.  
    44. Why we haven't taken potential at c due to point mass also?
    9 years ago by prakhar katariya

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  44.  
    45. A body of mass 1 Kg weighs 1/6 on the moon. If the moon radius is 1.768 x 10^6 m then what will be the mass of the moon?
    9 years ago by Suvradri Maitra
    Ans 1 ->
    As the acceleration due to gravity on earth is 9.8m/s^2 Therefore; ((G* mass of moon*1)/Radius of moon^2)=9.8/6
    8 years ago by Jatin Vyas

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  45.  
    46. sir for acceleration or equillibrium cases we are told to balance forces only in direction of motion or perpenendicular to direction of motion so why did here you balanced forces in different directions rather than balancing it in direction of centripetal force and perpendicular to it
    9 years ago by Anuj Thareja

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  46.  
    47. How does tsinO=gm^2/r'^2
    9 years ago by Obnoxious
    Ans 1 ->
    perpendicular factor of tention tsin@should be equal to the gravitational force for eqm
    3 years ago by himanshu

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  47.  
    48. Won't the answer of above question be v=(GM/R) ?????????
    9 years ago by Ritik Bompilwar

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  48.  
    49. A man weighs 60kg at earth surface.At wgat height above earth's surface weight becomes 30 kg? given--radius of earth=6400km.
    9 years ago by Nishtha Goel
    Ans 1 ->
    Use the relation of g at a height h above the earth surface given as g/2=GM/(Re+h)^2 this will give you h...
    9 years ago by Physics Galaxy

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  49.  
    50. Respected sir i thinks the graph should be started below (-ve) of gravitational field axis as it is an attractive in nature??
    10 years ago by sudeep khare

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  50.  
    51. It is considered that we hav infinite space (vacuum ).in universe Out of our earth. So can I say that earth is balancing the a very great pull of vacuum in order to keep atmosphere at its place?
    10 years ago by Kamal

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  51.  
    52. how is gravitational force is an unbalanced force
    10 years ago by BALAJI
    Ans 1 ->
    unbalanced force acting on a body is one which causes acceleration in body. When only gravitational force is acting on a body and it is in free fall state then gravitational force is an unbalanced force. When we consider a book placed on a table where gravitational force on book is balanced by the normal contact force on book by table then these two forces are taken as balanced forces...
    10 years ago by Physics Galaxy

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  52.  
    53. how can you say gravitational force is unbalanced force
    10 years ago by BALAJI
    Ans 1 ->
    balanced and unbalanced forces are discussed when two or more forces act on a single body... We cannot talk about balanced or unbalanced force only for one force whether it is grav or any other type..
    10 years ago by Physics Galaxy

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  53.  
    54. derivation of gravitational field and potential at a point between the 2 surfaces of a uniform thick spherical shell
    10 years ago by aashi sharma
    Ans 1 ->
    You can consider an elemental shell of width dx at a radius x in the thick portion and due to this shell find the grav field at the point distant r from centre and integrate the result from 0 to r. For grav potential you can use the relation V = - int (g.dx) from infinity to by using g(out) and same from R to r using g(in) calculated above...
    10 years ago by Physics Galaxy

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  54.  
    55. 3 equal masses are kept at the vertices of of a equilateral triangle.calculate net force on each mass??
    10 years ago by annad singh
    Ans 1 ->
    You can find the force by Gm1m2/r^2 on each and calculate the vector sum of two forces acting at 60° on each mass...
    10 years ago by Physics Galaxy

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  55.  
    56. what is the theoritical reason of g at centre is 0
    11 years ago by Harshit Jain
    Ans 1 ->
    an object at the center of earth feels equal attractions from all sides
    10 years ago by Ch Vishal

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  56.  
    57. how to prove the solid angle part? (dm1 = k(x1)^2
    11 years ago by manish reddy yedulla
    Ans 1 ->
    You need to refer physics articles in download sections of PG...
    10 years ago by Physics Galaxy
    Ans 2 ->
    To understand in detail you can mail to ashisharora@physicsgalaxy.com
    10 years ago by Physics Galaxy

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  57.  
    58. how to prove the solid angle part? (dm1 = k(x1)^2
    11 years ago by manish reddy yedulla
    Ans 1 ->
    You need to refer physics articles in download sections of PG...
    10 years ago by Physics Galaxy

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