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

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  1.  
    2. Respected Sir... At 1:01 why same friction acts on 6kg block sir .. pls explain sir
    3 years ago by Vamsi K

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  2.  
    3. yay video lectures Hindi ma ni h Kaya
    4 years ago by Ved prakash Kaswan

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  3.  
    4. Good evening sir, my name is Swapnil Acharya from j
    4 years ago by Swapnil Acharya

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  4.  
    5. sir what is the necessity of calculating the 'a' sir, I am not getting convinced in that part sir and then you are equating that with the friction with the mass of the 5 kg bloack with the common acc. How thats possible i am not able to understand kindly help me with this doubt sir as soon as possible
    5 years ago by Kartik Parameshwaran

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  5.  
    6. Sir how is the kinetic friction directly proportional to the Normal contact force and sir on what does the coefficient of kinetic friction depend. PLS CLARIFY MY DOUBT SIR.
    5 years ago by Kartik Parameshwaran

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  6.  
    7. can you give me some more sheets for jee 2020
    5 years ago by aryan agarwal

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  7.  
    8. sir F should be greater than 9N because if static friction constant = kinetic friction constant then ?
    5 years ago by Yash Veer Nagar

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  8.  
    9. sir what are you differentiating and why ? pls explain sir
    5 years ago by Yash Veer Nagar

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  9.  
    10. Nice Explanation
    5 years ago by AKASH

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  10.  
    11. sir why the friction value will be so small initially and we can take common acceleration?
    6 years ago by

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  11.  
    12. Sir, this concept is not there in your book mechanics.please make sure you will update it in next edition.Thank you Sir in advance
    6 years ago by Ajith Kumar

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  12.  
    13. Is friction always dessipates enrgy
    6 years ago by mahesh Hingankar

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  13.  
    14. sir in the 10 and 11 example why have you solved them differently??
    6 years ago by Divit Goyal

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  14.  
    15. sir why would the 2kg block will not start sliding first although it's limiting friction is less than 4kg block??
    6 years ago by Divit Goyal

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  15.  
    16. sir why would the 2kg block will not start sliding first although it's limiting friction is less than 4kg block??
    6 years ago by Divit Goyal

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  16.  
    17. sir great
    7 years ago by shib csk

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  17.  
    18. will angle of repose change if we apply an additional force on body in the direction of gravitational force ?
    7 years ago by Yogesh Kukreja
    Ans 1 ->
    Seems like there wouldn't be any effect on the angle of repose as the Net Force would be cancelled on both the sides of the equation.
    6 years ago by Adarsh Mishra

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  18.  
    19. Sir in module 6 if the force is greater than 4mg/new than the upward force on the block will be more than mg then it will not stay in rest
    7 years ago by thanish bolla
    Ans 1 ->
    no
    6 years ago by Mahesh Kumar

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  19.  
    20. Is there any your offline course sir?
    7 years ago by Sovan Kumar Panigrahy

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  20.  
    21. can anyone explain me the answer of question 2. my answer is 'c' option.
    7 years ago by Vinayak Singh

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  21.  
    22. Very helpful Sir, you are great
    7 years ago by Nittue

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  22.  
    23. THE COEEFICIENT OF FRICTION BETWEEN TWO SURFACES IS 0.2 WHYTHE ANGLE OF FRICTION IS tan-1 0.1
    7 years ago by Dharamjeet Singh
    Ans 1 ->
    why??
    7 years ago by Dharamjeet Singh

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  23.  
    24. WHAT IS THE DIFFERENCE BETWEEN STATIC AND LIMMITING FRICTION?
    7 years ago by Dharamjeet Singh
    Ans 1 ->
    the value of static friction tells you about the friction when thw body is at rest. its max value is given by :- Fs= (COEFFICIENT OF FRICTION) mg when the value of friction is more than limiting friction, the friction now is Kinetic friction.
    7 years ago by Anmol Mishra

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  24.  
    25. Answers to question from 11 to 20 are not correct(dubious) right?
    8 years ago by Udit Gupta

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  25.  
    26. Is coefficient of friction dependent on dependent on normal force? The QuSet answer says so.
    8 years ago by Swapnil Das
    Ans 1 ->
    Yes.It should be independent but many of the QueSet answers seem wrong to me too!
    8 years ago by Prayush Dawda
    Ans 2 ->
    no it is not depend on normal force...
    7 years ago by Anmol Mishra

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  26.  
    27. sir when two blocks are kept one above the other and there is friction present betwn the ground and the lower block so for the max frictional force on this block normal reaction should be equal to the weight of this block or the total weight of the system
    8 years ago by
    Ans 1 ->
    normal reaction at the bottom will always be the total weight in this case... and normal reaction between the the blocks will be equal to the weight of upper block only... and it is nothing to do with friction...
    8 years ago by Physics Galaxy

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  27.  
    28. sir i have a problem of forgetting things i learnt about friction and it seemed very easy the next day when im not able to recall i revise using the notes i made while listening to the videos but it doesnt help im forced to watch it again pls give some tips
    8 years ago by
    Ans 1 ->
    its better you make notes after watching the video... within few days you will be able to recall what you want... even solved examples and advance illustrations you should first watch and then attempt on your own next day... it will also help you...
    8 years ago by Physics Galaxy

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  28.  
    29. sir can we say this is a case of pseudo force
    8 years ago by Sankar Nampoothiri KM
    Ans 1 ->
    I have already explained that every problem can be solved by with or without pseudo force... its upto you how you wish to solve the problem ie in which frame of reference you wish to solve the problem...
    8 years ago by Physics Galaxy

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  29.  
    30. Sir, in case of problems dealing with more than one block on rough ground, and forces applied on both sides, from which side we should start writing forces equation and limiting friction?
    8 years ago by Jayanth Phani Sai Y
    Ans 1 ->
    From any block you can write based on the actual motion of blocks if considered to be moving together... thats the starting point of the solution to the question...
    8 years ago by Physics Galaxy

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  30.  
    31. sir in the last isnt Normal reaction of 5kg block is 25g
    8 years ago by charan
    Ans 1 ->
    as 5kg block is placed on 20kg block the normal reaction on the two blocks at contact is due to the weight of 5kg block only so its 5g...
    8 years ago by Physics Galaxy

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  31.  
    32. can u tell me how equation no 2 came ?
    9 years ago by Tanvi Pahwa

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  32.  
    33. in this QuSet one of the question was that if the normal force is doubledthen coefficient of friction is also doubled. how??
    9 years ago by SANIKA BHAGWAT
    Ans 1 ->
    coefficient of kinetic friction
    9 years ago by Manav kapur

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  33.  
    34. Does work done by the friction always negative ?if no then why and if yes then why?
    9 years ago by MANISH RAJ
    Ans 1 ->
    It can be positive if the motion of the particle is in the same direction as that of friction...for example... http://i.stack.imgur.com/KZuXl.png in this image, the block 1 will apply friction to block 2 towards right direction. So the block 2 will move towards right.
    9 years ago by Prateek Kumawat
    Ans 2 ->
    Not necessary. it is negative only when the point of application of friction is having displacement opposite to the direction of friction... it can be positive in case when a body starts its motion due to friction...
    9 years ago by Physics Galaxy

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  34.  
    35. while drawing a line on a paper friction force acts on paper in the same direction along which line is drawn on the paper. why?
    9 years ago by rajat
    Ans 1 ->
    when you move the pen to the right,point of contact will undergo relative motion w.r.t ground so friction would act opposite to direction in which point ball would tend move.(frictional force would provide torque to the ball and hence it would undergo rolling)
    9 years ago by Mukul Mahaliyan

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  35.  
    36. why it is easy to pull a heavy object that to push it on a level ground?
    9 years ago by rajat
    Ans 1 ->
    draw the fbd n u ll find that in case of pulling the normal reaction decreases thus frictional force decreses hence it is easy to pull.
    9 years ago by rashu tyagi

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  36.  
    37. condider a cylinder of mass M resting on a horizontal rug that is pulled out from under it with a acceleration 'a' perpendicular to the axis of a cylider.it is assumed that clinder doesnot slip. What is the friction at the point of contact of cylinder and the rug?
    10 years ago by deepak

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  37.  
    38. A car is accelerating with acceleration = 20 m/s2. A box of mass 10 kg is placed inside the car is in contact with the vertical wall. The friction coefficient between the box and the wall is µ = 0.6 and take g = 10 m/s2 The net contact force between the vertical wall and the box is only electromagnetic in nature. Is this statement true or false ? If it is false, what is the nature of other contact forces ?
    10 years ago by Tushi Phul

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  38.  
    39. Sir , the lower block will start sliding only when F=12N , not >12 .
    10 years ago by Tejan Gupta
    Ans 1 ->
    Dear Tejan... pl correct yourself and first read videos from fundamental level... as given friction coefficient of friction are same for both static and kinetic values so block will not slide at 12N...it will slide at F>12N... It will slide at 12N only if kinetic coefficient is less than static coefficient...
    10 years ago by Physics Galaxy
    Ans 2 ->
    yup
    7 years ago by Shantanu Kapoor

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  39.  
    40. A 60kg body is pushed horizontally with just enough force to start it moving across a floor and the same force continues to act afterwards . the coefficient of static friction and sliding friction are 0.5 and 0.4 respectively .the acceleration of the body is ?
    10 years ago by Abhishek
    Ans 1 ->
    Limiting frictional force = Static friction coefficient * g * mass of body = 0.5 * 9.8 * 60 = 294 N Thus, external force acting on the body is 294 N. Frictional force due to kinetic friction = µ k * g * mass = 0.4 * 9.8 * 60 = 235.2 N As the same force continues to act on the body opposite to the direction of frictional force, net force = 294 - 235.2 N = 58.8 N Thus, acceleration of body = F/m = 58.8 / 9.8 = 6 m/s^2.
    10 years ago by Tushi Phul

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  40.  
    41. why smaller steps are taken while walking on ice ?
    10 years ago by AKASH GOYAL
    Ans 1 ->
    Smaller steps leads to static friction between ice and shoes. If larger steps are taken friction may turn to kinetic and person can slip and fall...
    10 years ago by Physics Galaxy

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  41.  
    42. An object of mass ‘m’ is projected on the rough horizontal surface of coefficient of friction ‘meu’ with some initial K.E., the time ‘t’ taken before stopping is proportional to mass and meu in what manner?
    10 years ago by sreeram
    Ans 1 ->
    You can use impulse momentum equation here.... use mv - (mu)mgt = 0 which gives you time of stopping which is t = v/(mu)g and you can calculate v from KE as KE = (0.5)*mv^2 so you get t...
    10 years ago by Physics Galaxy

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  42.  
    43. An object of mass ‘m’ is projected on the rough horizontal surface of coefficient of friction ‘m’ with same initial K.E., the time ‘t’ taken before stopping is related to mass and coefficient of friction in what manner?
    10 years ago by sreeram

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  43.  
    44. A person is standing on a weighing machine placed on the floor of an elevator.The elevator starts going up with some acceleration,moves with uniform velocity for a while and finally decelerates to stop.The maximum & minimum weights record are 72kg & 60kg.Assuming that the magnitude of the acceleration and the deceleration are the same, Find:-(1)true weight of the person (2)the magnitude of the acceleration.
    10 years ago by Tushar Sinha
    Ans 1 ->
    awesome sir
    7 years ago by Aditya Chatterjee
    Ans 2 ->
    1)66kg 2)10/11m/seconds square
    7 years ago by eshwar

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  44.  
    45. why minimum force reqd is limiting .at that value body has no net force so how does it startted
    10 years ago by ayush malpani
    Ans 1 ->
    When external force approaches the limiting value of friction...actual friction reduces to kinetic friction due to which body starts moving...
    10 years ago by Physics Galaxy

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  45.  
    46. Physics galaxy Mechanics Vol-I pg. no. 198 question no, 4
    10 years ago by govinda totla
    Ans 1 ->
    Pl ask any specific doubt of PG books on mail ID ashisharora@physicsgalaxy.com
    10 years ago by Physics Galaxy

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  46.  
    47. how we accelerate our vehical ? -state according to NEWTONS III law .
    10 years ago by neeraj khinchi
    Ans 1 ->
    simple your vehicles push the earth back so that you move forward
    10 years ago by Ch Vishal
    Ans 2 ->
    the vehicles move because of newton's third law of motion i.e action reaction force and therefore because of friction vehicle can move as it push the earth backwards and according to newtons third law earth apply an equal reaction force and thus vehicle move but earth not seems to be moving because of greater mass
    10 years ago by Shreyansh jain

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  47.  
    48. Q21 hc vema exercie friction
    10 years ago by akshay
    Ans 1 ->
    Any problem of any book you can directly ask on mail ashisharora@physicsgalaxy.com
    10 years ago by Physics Galaxy

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