Make note that he has taught this lecture numerous times, but every time, for every audience, he delivers energy, excitement, anticipation and joy at the realities of physics. He is one in a billion!
Last comment 6 years ago.... wow. I am a design engineer in the UK, and I just want to say Prof. Lewin, I watch many of your lectures and they have helped me take my understanding, and my career to the next level. I love your lectures. I often fall asleep with one playing in the background. Much love and respect to you always. An inspiration. Thank you so much. Ade
First time(I'm in 11th grade) seeing a physics teacher who is very very clear to his thoughts. The clarity of his thought process and analytical thinking for problem solving has inspired me very much. All my physics teacher mess up every concept they teach, so i dont get a sharp picture of the concept. But watching his videos have made me to love physics. I wanna do research in physics
JEE aspirants are blessed and very lucky to have dear professor Walter Liwen helping them with down to earth explanation keeping Philosophy of Nature in the front not mathematics to which many professors succumb to Thank you very much sir and God bless you
Sir, I'm an IIT aspirant and always loved physics. just now because of my new physics teacher I felt a little boring while studying physics. but since the time i began watching your lectures, my love for physics has grown to new heights and I'm able to understand the concept to the very core. just want to thank you for what you've done. I'm religiously following your channel these days.
How lucky are the students of today . They have the internet and have access to great lecturers. During my days as a engineering student in the eighties we had to read all these physics concepts from a book, solve the problems at the end of the chapter to prepare for recitations.
8.01 Physics Hans C. Ohanian 2nd edition W.W. Norton & Company ISBN 0-393-95748-9 8.02 Physics for Scientists & Engineers by Douglas C. Giancoli. Prentice Hall ISBN 0-13-021517-1 8.03 Electromagnetic Vibrations, Waves and Radiation by Bekefi and Barrett. The MIT Press ISBN 0-262-52047-8
I have the sixth edition and I think it is quite good. One big advantage with the US system using syllabus is that it differs very little between different textbooks. The question and problems from Ohanian is quite easy to find on the internet. The big problem is that you have to study hard between the lessons no matter what textbook you use 😊
Sir in few lectures, Whenever I watch a new lecture I strongly feel this is your best lecture. But now I realise your every lecture is a best lecture. ❤❤just mind blowing
Bestest lecture in Physics (of Friction), I have ever seen in my life..!!! Respected Walter Lewin Sir you are Great, simply amazing..!!!💯💯 I am 16 years old JEE Apsirant from India, your lectures give me the realistic feel of Physics, of what is taught in books..!!! Sir please read my comment and if possible please reply, It will make my day..!! 🙏🙏❤❤❤
I sincerely thank you for the explanation on mu, I'm through 3 mechanics classes and 1 physics class, in each one we used mu for loads of different problems but noone explained it to me before what the mu actually is.
You know I always can't help but watch every lecture of yours that I come across even when they are on a subject that I'm clear with but your demonstration is even more insightful. Thank you so much also for quickly responding to our comments in the comments section. I doubted you'd be able to do that.
It's really nice to see that at the beginning you where apologizing about your voice, but later on you can hear your love for physics as you get more and more enthousiastic about it and you almost don't hear your cold anymore! :D
I am a 15 years old guy from India.... And we are taught these things for IIT preparation...... In my class... Many students were facing problems.. In this topic and we were crying literally while solving questions of friction combined with pseudo force.... Lift and acceleration..
I just got into 11th grade and i was feeling down vut after i watched your last lecture in mit i got super motivated ...... thnx for helping sir ..... btw i am from india
first you need to know about traction. traction- traction is force used to generate motion between a body and a tangential surface. So it's like friction between RIGID bodies.(rigid bodies-all points on a perfectly rigid bodies have a relative velocity 0 with each other). Traction can also refer to the maximum tractive force between a body and a surface, as limited by available friction. NOW wider tires have better traction. So there's a misconception that -"wider tires have better traction because of surface area". Soft compound tires are required to be wider in order for the side-wall to support the weight of the car. softer tires have a larger coefficient of friction, therefore better traction. you canjust search it up if you want more details. BUT here a much more complex answer i found on internet when i searched it up - (this copy pasted )- Wide tires were innovated at the request of the legendary Micky Thompson. Thompson had a design for a 1963 Indy Special*, a clever car designed to lower the aerodynamic drag by reducing the frontal area of the car. He made the car as low as possible with the gas tanks on either side between the front and rear wheels and with special ultra low profile tires that barely protruded above the gas tank frontal exposure. The tires were about 50 series at a time when racing tires were all about 80 or 90 series. IIRC, only one manufacturer would build tires like that for him, I think it was US Royal, (UniRoyal), one of the lesser tire companies. The unforeseen benefits of wider tires included a shorter sidewall for less carcass deflection with lower air pressure and a more compliant structure and more rubber surface exposed to the cooling of the road surface and air. Tires like that can run softer compounds without overheating the tread, allowing greater coefficients of friction. The contact patch is relatively shorter and with a more compliant tread, proportionately less contact area is undergoing inferior sliding friction as opposed to superior static friction. LOTS more grip. I don’t believe all these benefits were appreciated with Thompson’s tires, but the manufacturers soon recognized them. By 1965 the wide tire revolution was on! *Indy Special denotes cars built exclusively for the Indy 500 race. They were innovative turbine cars, steam engine cars, tandem wheeled (long before Tyrrell), winged cars (long before Jim Hall) and low-profile tires. Some of them were weird like the Kolbe “Curvebank” car. The early 1960s were the heyday of innovative Specials. NOTE pressure decreases as air molecules in side the wider tire don't collide with as much force as in less wider tire, also the heat from tire expands the tire so wider tires wouldn't burst as easily. ALL THESE WERE FROM DIFFERENT PERSPECTIVES. an engineer's and physicist.
Well friction may be the same but it’s very different when it comes to contact area. Friction generates heat which is produced within the contact area of the tyre, so the larger the tyre, the larger the contact area and thus the heat is generated by a larger surface and will keep the consequent temperature relatively low, so the tyre will not “burn” due to overheating.
Since the Friction Force = mu * mgcos(alpha) , won't the fictional force also depend on mgcos(theta) = N ? And N also depend on Mass m? I have never found a physics teacher like you , both in knowledge and the ability to explain physics! Truly you are a great teacher !
watch at 5:20 The friction coefficient is independent of mass. That means that if you take 2 objects with very different mass, they will start to slide at the very same angle alpha - *Thus when these 2 objects start to slide you cannot tell what there masses are* Thus the sliding behavor (sliding angle) is NOT a function of mass.
I just wasted my 2 yrs of jee prep but at last i found sir walter lewin i just got my 90percent syllabus completed through his lectures thanks to a living legend of physics
Thank you Dr. Lewin. At 5:45 you pointed out that the coefficient of friction is not at all dependent on the mass of the object. I was surprised to notice that your calculation also canceled out g, so that the friction coefficient is also independent of the gravitational acceleration. So I suppose that means that the tires of a truck would have the same grab on a road on the moon, or for that matter on Jupiter, as they would on the earth. Would you agree with that? It seems strange.
+luvinthe jazz The maximum frictional force is proportional to the normal force acting on an object. If you place an object on a table (with friction coeff mu) on Earth the normal force is mg. If you place it on a similar table on the Moon the maximum frictional force is therefore 6 times lower.
+Lectures by Walter Lewin. They will make you ♥ Physics. OK, so the coefficient is the same anywhere, but the different gravitational acceleration will result in a lesser force on the moon, a greater force on Jupiter.
luvinthe jazz these all lectures support that gravity,weight in universe can change but there is one fundamental thing in mechanics that never change and that is mass. It's my point.
Wider tires are normally made of a softer compound which has a higher friction but needs to be wider in order for the side wall of the tire to be able to support the weight of the vehicle. So the extra width is necessary because the rubber is softer(so you need more to keep the side wall from buckling)and offers more traction. Also reduces wear because you have a greater contact area. Hope I paraphrased that correctly and clearly.
I am a 11th class student of PHYSICS WALLAH .And I am revising the lecture. And my teacher Rajwant Sir has made me understand all the concept perfectly that I can understand every words prof. speaks.🙏🙏🙏💓💓
I’m not sure I understand your demonstration of the objects sliding down the incline plane. Clearly, as you show, when the object first moves, mg sin alpha = mu*N = mu*mg*cos alpha. This allows you to compute mu (the coefficient of friction) for a specific object (made of some material) on a specific incline plane (made of some material). Thus, I agree that for a specific object, the surface area of the object that rests on the incline plane does not matter. However, won’t different objects have different coefficients of friction and so the angle at which they start to slide be different? Also, won’t different masses of two objects made of the same material have different coefficients (as mu*N changes) of friction and therefore start to slide at a different angle? In essence, what I am positing is that the experimentally determined coefficient of friction may very well be determined by tangent alpha, but the mu derived only applies to the specifically chosen objects in the experiment. PS. I am one of your biggest fans and you are a stimulant to critical thinking.
SIR I AM YOUR BIGGEST FAN FROM INDIA...SIR I ALWAYS WANTED TO LEARN PHYSICS FROM YOU...SIR I AM IN CLASS 11 AND PREPARING FOR IIT JEE...AND I HAD WATCHED ALL YOUR LECTURES FROM THIS CHANNEL...SIR I WISH IN FUTURE I MEET YOU AND HAVE SOME KNOWLEDGE ABOUT THE ULTIMATE LOVING PHYSICS YOU TEACH...REALLY SIR I ASSURE THAT I WILL MEET YOU..AND YOU WILL BE HAPPY TO SEE ME....LOTS OF RESPECT FOR SIR WALTER LEWIN ( THE MAN WHO MADE PHYSICS MUCH EASIER THAN ANYTHING)
I sell material handling equipment and we sell machinery mover that uses a compressor that blows air underneath and you can push tons around with one hand.I also sell electric forklifts and you lectures on batteries have helped me immensely.Next hydraulics and I will have good working knowledge of those machines far in excess of the manufacturer manual
I know all the formulas and calculation but don't know how to apply then in real scenario... But when I see your lectures sir this helps me imagining and observing comparing it with real world.🙂😇😇 Genuine Thank You Sir..
Thank you so much Sir Walter Lewin. I can't thank you enough, I wasn't able to understand this topic, thanks alot sir I don't have words to explain you're a marvellous teacher. You're literally helping me in my NEET preparation. May God bless you with lots of happiness!
Hello Dr. Lewin! The lecture was very clear and concise, although I've always had this one doubt which my teachers refused to address by dismissing it as rather basic and common knowledge; could you please enlighten me as to how I can resolve the vectors in the x and y-direction like you did at 3:20 and 14:00? Thanks in advance!
As you can see that mg is acting in downward direction,when u draw a line opposite to normal force that line represents the cosine component of mg with angle alpha(when u draw a triangle with mg as opposite side to angle alpha ,u will see that the angle between mg and the side which is in opposite direction to normal force is also alpha),and its sin component is mgsin alpha,that's how the vector mg is resolved.Hope it's clear
5:38 Hi sir. I think that it is intuitive that the friction coefficient is independent of the mass of the object. Because if you double the mass, friction will become twice as big, but gravitational force will become twice as big too so the effects cancel out.
According to me race cars have wide tires so that friction applied on tyres is large and avoids slipping(it has a close relationship with velocity) as it allows friction to act in more area as illustrated in your lecture
I was searching to find a video to help my 2nd year degree s oil m echanics students to understand better the Coloumb's theory (the same French engineer who is also known for the electrical discharge theory) and I've co me across this video. To be very honest, Civil Engineering is nothing but Newtonian Mechanics. We Engineers are applied physicist. Prof ., I really enjoyed your video and will share it with my students if you allow.
At min 7:32 you say that a bit of water on the surface of the plank or of the objects that you are sliding will make the friction coefficient larger. However a larger friction coefficient would make the maximum frictional force acting against the object greater and thus increasing the angle at which the object will start to slide; this is a bit counterintuitive as I would say that with water the surface is more slippery and the object will start to slide at a smaller angle. So my question is whether you made a mistake, and if instead water on the surface of the plank would make the friction coefficient smaller??,
my plank is made of wood. It's very smooth uniformly sanded. But the wood is not varnished. If you put a drop of water on it locally the friction coeff will go UP. Do not confuse this with hydro-slipping on the road.
Professor Lewin, why are we still driving cars with wheels? Why can't we have hover cars that blow air out of their bottom? What are the difficulties of making such cars? Could you briefly explain and point me to further readings? Thank you!
i would really appreciate if you could answer me this sir Walter lewin; how about the coefficient of static friction for a body moving horizontally and not on an inclined plane
8.01 Physics Hans C. Ohanian Physics 2nd edition W.W. Norton & Company ISBN 0-393-95748-9 8.02 Physics for Scientists & Engineers by Douglas C. Giancoli. Prentice Hall Third Edition ISBN 0-13-021517-18 8.03 Vibrations and Waves by Anthony French CRC Press ISBN 9780748744473 8.03 Electromagnetic Vibrations, Waves and Radiation by Bekefi and Barrett. The MIT Press ISBN 0-262-52047-8
Hello professor Lewin. I have been working hard this autumn with tension and friction. It is very interesting but sometimes very confusing. One of the questions in assignment 3, 3:11, about a woman pushing a wooden box of mass 60 kg on a frictionless ramp did me a little confused. If the ramp was frictionless shouldn’t both the lady and the box sliding down? Else it wasn’t hard to calculate if I supposed she had super shoes.
Thank you for your quick answer. I have only a few questions two answer now and then I will get my reward. That is to look at your 10th lecture about Hooke’s Law and Springs. Thank you so very much for your lectures. I really look forward to see them all.
@@lecturesbywalterlewin.they9259 Why is there a reforming force? Why do molecules want to regain its position? One more thing, How about a book balanced on a vertical nail?
@@lecturesbywalterlewin.they9259 Still could not understand the physical origin for that restoring force? What if we balance a book on a vertically placed nail? The book will also get deformed.
Lectures by Walter Lewin. They will make you ♥ Physics. x direction component is cos whileas y direction component is sin but here it is opposite......
>>>x direction component is cos whileas y direction component is sin>>> BIZARRE misconception it depends on the geometry. *Please brush up on your trigonometry and vector decomposition.* en.wikipedia.org/wiki/Vector_decomposition
Hello Sir. I have a question. If we imagine there is a perfectly frictionless surface, can a man stand still on it, provided that he doesn't exert any horizontal force? (I think yes)
Sorry, I meant at 24:41, when you set up the second equation with T and a. The second mass is moving in a different direction than the first mass. What allows us to assume it is moving with the same magnitude of acceleration as the first one?@@lecturesbywalterlewin.they9259
hello, i want to ask question, i try to solve assignment (35:00) but i couldn't , because i don't know acceleration and static friction , also WALTER LEWIN shows the formula but i dont understand which one (1) or (2)
@Lectures by Walter Lewin, I have watched through the Vedio a lot of times, but I still cannot understand why as the mass increases, the angle it slides down didn't change, because according to the equation: Fmax=muN, as the mass of the object increases, the N must have been also increases, and so mu didn't change, N increases, and so Fmax must increases, this means that it needs more force in order to let in move, as a result the angle should increases in this way of thinking. May you help me to explain the question? Thankyou.
sir you asked why racing car have wide tires. is it due to the fact to reduce the pressure on the tire and also to increase the surface area to increase the heat transfer from it so that the heat generated due to friction do not burn the tires.
Oh! I just watched one of your iit kanpur video so I asked it, btw many people call him the Walter lewin of India(which is indeed an achievment). Were your lectures in india recorded and also how was yor experience in my country.
the system of equations at 25:53 is a bit confusing. If the mass hanging on the string is heavier than the object, then how could they have the same acceleration? Is it because as it falls down it losses weight and becomes as heavy as the mass on the incline? If so will the mass on the incline stop accelerating upwards once the mass hanging on the string reaches the same weight ? An explanation will be HIGHLY appreciated as I think understanding these equations are a big factor in physics, please Walter Lewin, come to my rescue
Are you saying that both masses will recive the same acceleration even though they have different masses? Or should there have been a subscript 2 under the acceleration of mass 2. so the second equation should look like M2g - T = M2a2 And not M2g -T = M2a because this equation indicates that they get the same acceleration
I cannot add to the clarity of my lecture. If 2 masses are connected by a stiff string the magnitude of their accelerations *MUST* be the same. If not, the string would break.
I am in 9 grade i started facinating about physic and i am studying from our lecture sometime it is little fast but i slow the video and unterstand the concept here my interestin physic is increasing more and more with the increase in knowlege about physic
I’ve had a few auto technicians tell me that. They would say wide tires act like snow shoes and “float” on snow covered roads and that narrow tires “dig in” like high heeled shoes.
In friction if the objects deform each other then things change. Very large tires will float on top of the snow. Smaller tires push their tread into the snow connecting the two. Ideally you want the largest 'connected' area possible so you can have too big or too small and a lot depends on the speed.
It shows that without out resistance , gravity is not pulling stuff directly to the center of the Earth its more resistance that is directing that .And then equal so there must be a cushion of no resistance were it is purely gravity that governs the track of the Moon around the Earth, which they are floating as such
As per the formula, Fmax is directly proportional to the normal force (which is also dependent on mass) and the coefficient of friction. So, in the experiment where the two plastic bins were taken, and a mass of 200g was added to one, shouldn't the lighter plastic bin have gone first? As for the lighter plastic bin, the Normal force is less and thus the value of Fmax is less.
11:23 so what's the answer for that? i tried searching on the net but all I could find was that it's related to surface area but then it's clearly not :(
Thinking about the car parked on the 45 degree slope: If size of the tyre (tire) contact patch and mass of the car does not effect the coefficient of friction before the car starts sliding on the slope, why does increasing the size of the contact patch increase the lateral grip of a car going around a corner? Excluding any downforce etc I dont understand what other factors are at play (and really I should!)
I believe I have found the answer (or begining of the answer) here: www.physlink.com/education/askexperts/ae200.cfm "This is a good question and one which is commonly asked by students when friction is discussed. It is true that wider tires commonly have better traction. The main reason why this is so does not relate to contact patch, however, but to composition. Soft compound tires are required to be wider in order for the side-wall to support the weight of the car. softer tires have a larger coefficient of friction, therefore better traction. A narrow, soft tire would not be strong enough, nor would it last very long. Wear in a tire is related to contact patch. Harder compound tires wear much longer, and can be narrower. They do, however have a lower coefficient of friction, therefore less traction. Among tires of the same type and composition, here is no appreciable difference in 'traction' with different widths. Wider tires, assuming all other factors are equal, commonly have stiffer side-walls and experience less roll. This gives better cornering performance. Answered by: Daryl Garner, M.S., Physics teacher MacArthur High School, Lawton, OK"
On an unrelated note: Thank you so much for making these videos available. I find them absolutely fascinating and have inspired me to take an interest in mathematics and logical thinking. I really appreciate the effort you have made for us all.
THIS IS PROBABLY THE BEST LECTURE ON FRICTION THAT I'VE WATCHED IN MY LIFE SO FAR.
Make note that he has taught this lecture numerous times, but every time, for every audience, he delivers energy, excitement, anticipation and joy at the realities of physics. He is one in a billion!
Last comment 6 years ago.... wow. I am a design engineer in the UK, and I just want to say Prof. Lewin, I watch many of your lectures and they have helped me take my understanding, and my career to the next level. I love your lectures. I often fall asleep with one playing in the background. Much love and respect to you always. An inspiration. Thank you so much. Ade
bro do you have notes of these lectures
One of the best teachers of Physics I've ever seen. Helped a lot for the preparation of JEE....
:)
Sir, do you have any plans to visit India??
@MSA 212 probably not
@@lecturesbywalterlewin.they9259 sir thanks for your practical demonstrations and ur teachings for JEE Advanced IITJEE ,INDIA
I am also preparing for JEE but I don't have time to watch them
First time(I'm in 11th grade) seeing a physics teacher who is very very clear to his thoughts. The clarity of his thought process and analytical thinking for problem solving has inspired me very much. All my physics teacher mess up every concept they teach, so i dont get a sharp picture of the concept. But watching his videos have made me to love physics. I wanna do research in physics
bro do you have notes of these lectures
JEE aspirants are blessed and very lucky to have dear professor Walter Liwen helping them with down to earth explanation keeping Philosophy of Nature in the front not mathematics to which many professors succumb to Thank you very much sir and God bless you
Sir, I'm an IIT aspirant and always loved physics. just now because of my new physics teacher I felt a little boring while studying physics. but since the time i began watching your lectures, my love for physics has grown to new heights and I'm able to understand the concept to the very core. just want to thank you for what you've done. I'm religiously following your channel these days.
Ashish Dalal got iit?
@@ravitripathy2479 lol
@@kvvlavanya7226 😂
Iit mila bhai ?
So what happened? Did u join IIT?
great lecturer. i am taking intro physics now, bashing my brains out. he makes it much clearer. i also love his bracelets! brilliant interesting man.
:)
You have to help him getting the golden play button....
*And that is non negotiable*
and that we are not gonna discuss it again, we have already argued that
Hello guys am precious is physics that difficult
How lucky are the students of today . They have the internet and have access to great lecturers. During my days as a engineering student in the eighties we had to read all these physics concepts from a book, solve the problems at the end of the chapter to prepare for recitations.
1) Excellent proof to follow.
2) amazing demos
Where can I obtain the physics textbook, which you have used in this course?
8.01
Physics
Hans C. Ohanian
2nd edition
W.W. Norton & Company
ISBN 0-393-95748-9
8.02
Physics for Scientists & Engineers by Douglas C. Giancoli.
Prentice Hall
ISBN 0-13-021517-1
8.03
Electromagnetic Vibrations, Waves and Radiation
by Bekefi and Barrett.
The MIT Press
ISBN 0-262-52047-8
Thank you. I am a neurobiologist, but I was always fascinated by Physics.
I have the sixth edition and I think it is quite good. One big advantage with the US system using syllabus is that it differs very little between different textbooks.
The question and problems from Ohanian is quite easy to find on the internet.
The big problem is that you have to study hard between the lessons no matter what textbook you use 😊
Where can I buy Physics for Scientists & Engineers by Douglas C. Giancoli (ISBN 0-13-021517-1)? Thank you.
@@zcahhf8 bookfinder dot com compares books prices
one of the best PHYSICS TEACHER EVER BEEN !! GREAT!
Sir in few lectures, Whenever I watch a new lecture I strongly feel this is your best lecture. But now I realise your every lecture is a best lecture. ❤❤just mind blowing
Bestest lecture in Physics (of Friction), I have ever seen in my life..!!! Respected Walter Lewin Sir you are Great, simply amazing..!!!💯💯 I am 16 years old JEE Apsirant from India, your lectures give me the realistic feel of Physics, of what is taught in books..!!! Sir please read my comment and if possible please reply, It will make my day..!! 🙏🙏❤❤❤
I LOVE THESE LECTURES, thank you so much, Professor Lewin. I always watch your videos as supplemental study tools before and after my normal lectures
You're very welcome!
@@lecturesbywalterlewin.they9259 pls pin?
I sincerely thank you for the explanation on mu, I'm through 3 mechanics classes and 1 physics class, in each one we used mu for loads of different problems but noone explained it to me before what the mu actually is.
Amazing professor, this is helping a lot for my technical physics exam as a chemE student.
You know I always can't help but watch every lecture of yours that I come across even when they are on a subject that I'm clear with but your demonstration is even more insightful. Thank you so much also for quickly responding to our comments in the comments section. I doubted you'd be able to do that.
:)
@@lecturesbywalterlewin.they9259 oh sir one day I meet you iam physics chemistry and mathematics student but phy is first for me
U r my favourite physics teacher from now...bravo 👏 👏
C'est toujours un plaisir de revoir aussi cette video ....Ca parait tellement facile
It's really nice to see that at the beginning you where apologizing about your voice, but later on you can hear your love for physics as you get more and more enthousiastic about it and you almost don't hear your cold anymore! :D
:)
I am a 15 years old guy from India.... And we are taught these things for IIT preparation...... In my class... Many students were facing problems.. In this topic and we were crying literally while solving questions of friction combined with pseudo force.... Lift and acceleration..
I just got into 11th grade and i was feeling down vut after i watched your last lecture in mit i got super motivated ...... thnx for helping sir ..... btw i am from india
Why do race cars have very wide tyres? (11:25)
first you need to know about traction.
traction- traction is force used to generate motion between a body and a tangential surface.
So it's like friction between RIGID bodies.(rigid bodies-all points on a perfectly rigid bodies have a relative velocity 0 with each other).
Traction can also refer to the maximum tractive force between a body and a surface, as limited by available friction.
NOW wider tires have better traction.
So there's a misconception that -"wider tires have better traction because of surface area".
Soft compound tires are required to be wider in order for the side-wall to support the weight of the car. softer tires have a larger coefficient of friction, therefore better traction.
you canjust search it up if you want more details.
BUT here a much more complex answer i found on internet when i searched it up -
(this copy pasted )-
Wide tires were innovated at the request of the legendary Micky Thompson. Thompson had a design for a 1963 Indy Special*, a clever car designed to lower the aerodynamic drag by reducing the frontal area of the car. He made the car as low as possible with the gas tanks on either side between the front and rear wheels and with special ultra low profile tires that barely protruded above the gas tank frontal exposure. The tires were about 50 series at a time when racing tires were all about 80 or 90 series. IIRC, only one manufacturer would build tires like that for him, I think it was US Royal, (UniRoyal), one of the lesser tire companies.
The unforeseen benefits of wider tires included a shorter sidewall for less carcass deflection with lower air pressure and a more compliant structure and more rubber surface exposed to the cooling of the road surface and air. Tires like that can run softer compounds without overheating the tread, allowing greater coefficients of friction. The contact patch is relatively shorter and with a more compliant tread, proportionately less contact area is undergoing inferior sliding friction as opposed to superior static friction. LOTS more grip. I don’t believe all these benefits were appreciated with Thompson’s tires, but the manufacturers soon recognized them. By 1965 the wide tire revolution was on!
*Indy Special denotes cars built exclusively for the Indy 500 race. They were innovative turbine cars, steam engine cars, tandem wheeled (long before Tyrrell), winged cars (long before Jim Hall) and low-profile tires. Some of them were weird like the Kolbe “Curvebank” car. The early 1960s were the heyday of innovative Specials.
NOTE
pressure decreases as air molecules in side the wider tire don't collide with as much force as in less wider tire, also the heat from tire expands the tire so wider tires wouldn't burst as easily.
ALL THESE WERE FROM DIFFERENT PERSPECTIVES.
an engineer's and physicist.
@@raman249 then why did Mr Walter said that friction is independent of surface area(11:13)
Well friction may be the same but it’s very different when it comes to contact area. Friction generates heat which is produced within the contact area of the tyre, so the larger the tyre, the larger the contact area and thus the heat is generated by a larger surface and will keep the consequent temperature relatively low, so the tyre will not “burn” due to overheating.
The ending was really COOL!
This lecture in particular helped me solve big problems recently ❤
The flea circus is funny ,but the fleas are disgusting lol
We are very lucky to have a teacher like u..... 😊
You make my day sir ❤️🤞🏻
Since the Friction Force = mu * mgcos(alpha) , won't the fictional force also depend on mgcos(theta) = N ? And N also depend on Mass m?
I have never found a physics teacher like you , both in knowledge and the ability to explain physics! Truly you are a great teacher !
watch at 5:20 The friction coefficient is independent of mass. That means that if you take 2 objects with very different mass, they will start to slide at the very same angle alpha - *Thus when these 2 objects start to slide you cannot tell what there masses are* Thus the sliding behavor (sliding angle) is NOT a function of mass.
I just wasted my 2 yrs of jee prep but at last i found sir walter lewin i just got my 90percent syllabus completed through his lectures thanks to a living legend of physics
The most entertaining lecture on fiction, ever!
Thank you Dr. Lewin. At 5:45 you pointed out that the coefficient of friction is not at all dependent on the mass of the object. I was surprised to notice that your calculation also canceled out g, so that the friction coefficient is also independent of the gravitational acceleration. So I suppose that means that the tires of a truck would have the same grab on a road on the moon, or for that matter on Jupiter, as they would on the earth. Would you agree with that? It seems strange.
+luvinthe jazz The maximum frictional force is proportional to the normal force acting on an object. If you place an object on a table (with friction coeff mu) on Earth the normal force is mg. If you place it on a similar table on the Moon the maximum frictional force is therefore 6 times lower.
+Lectures by Walter Lewin. They will make you ♥ Physics. OK, so the coefficient is the same anywhere, but the different gravitational acceleration will result in a lesser force on the moon, a greater force on Jupiter.
+luvinthe jazz correct
luvinthe jazz these all lectures support that gravity,weight in universe can change but there is one fundamental thing in mechanics that never change and that is mass. It's my point.
in Nuclear reactions mass can also change.
Great lecture and wonderful demonstrations 😊
Professor W.L explained very well. I didn't understand when I took Newtonian Physics in my freshman year. Thank you Professor!
:)
Hence playing air hockey is so much fun..:D...
Wider tires are normally made of a softer compound which has a higher friction but needs to be wider in order for the side wall of the tire to be able to support the weight of the vehicle. So the extra width is necessary because the rubber is softer(so you need more to keep the side wall from buckling)and offers more traction. Also reduces wear because you have a greater contact area. Hope I paraphrased that correctly and clearly.
I am from India and preparing for NEET it is helping a lot for my concepts. Thank You so much sir 🙏
You are most welcome
Neet nikla bhai ?
Congratulations, Professor Lewin! May you have good health and a long life! To celebrate your birthday, I am watching this magnificent lecture. 🎊🎊🎊🎉🎉
I am a 11th class student of PHYSICS WALLAH .And I am revising the lecture.
And my teacher Rajwant Sir has made me understand all the concept perfectly that I can understand every words prof. speaks.🙏🙏🙏💓💓
That's great
For board level 😂😂😂
Am at at 12 grade but hates physics , hi guys
I’m not sure I understand your demonstration of the objects sliding down the incline plane. Clearly, as you show, when the object first moves, mg sin alpha = mu*N = mu*mg*cos alpha.
This allows you to compute mu (the coefficient of friction) for a specific object (made of some material) on a specific incline plane (made of some material). Thus, I agree that for a specific object, the surface area of the object that rests on the incline plane does not matter.
However, won’t different objects have different coefficients of friction and so the angle at which they start to slide be different? Also, won’t different masses of two objects made of the same material have different coefficients (as mu*N changes) of friction and therefore start to slide at a different angle?
In essence, what I am positing is that the experimentally determined coefficient of friction may very well be determined by tangent alpha, but the mu derived only applies to the
specifically chosen objects in the experiment.
PS. I am one of your biggest fans and you are a stimulant to critical thinking.
U are best professor of physics literally your vidoes make me fall in love with physics❤
SIR I AM YOUR BIGGEST FAN FROM INDIA...SIR I ALWAYS WANTED TO LEARN PHYSICS FROM YOU...SIR I AM IN CLASS 11 AND PREPARING FOR IIT JEE...AND I HAD WATCHED ALL YOUR LECTURES FROM THIS CHANNEL...SIR I WISH IN FUTURE I MEET YOU AND HAVE SOME KNOWLEDGE ABOUT THE ULTIMATE LOVING PHYSICS YOU TEACH...REALLY SIR I ASSURE THAT I WILL MEET YOU..AND YOU WILL BE HAPPY TO SEE ME....LOTS OF RESPECT FOR SIR WALTER LEWIN ( THE MAN WHO MADE PHYSICS MUCH EASIER THAN ANYTHING)
I sell material handling equipment and we sell machinery mover that uses a compressor that blows air underneath and you can push tons around with one hand.I also sell electric forklifts and you lectures on batteries have helped me immensely.Next hydraulics and I will have good working knowledge of those machines far in excess of the manufacturer manual
Wish I was born in the US and had an opportunity to study under the guidance of this legend🙏
Why you want to born in usa just go in mit and learn .
Me too how I wish there are different opportunities there😮
Flea circus! hahaha
Genius teacher.
This is actually very awesome I now feel physics as stress reliever and mind fresher
Man!! This theory made me fall asleep while my teacher was explaining but the way he explains!!! I didn't even blinked🤓
Me too 😅
Best of the best lectures....I happened to dwell in it....
I know all the formulas and calculation but don't know how to apply then in real scenario... But when I see your lectures sir this helps me imagining and observing comparing it with real world.🙂😇😇 Genuine Thank You Sir..
Keep watching
Hello rajatasoni am precious am 12 but bad at physics
Thank you so much Sir Walter Lewin. I can't thank you enough, I wasn't able to understand this topic, thanks alot sir I don't have words to explain you're a marvellous teacher. You're literally helping me in my NEET preparation. May God bless you with lots of happiness!
Hey Professor Lewin, I was was wondering what are the PIVoT videos mentioned in the assignments. Thank you for the great lectures.
everything what was then called PIVOT is now on my channel
Hello Dr. Lewin! The lecture was very clear and concise, although I've always had this one doubt which my teachers refused to address by dismissing it as rather basic and common knowledge; could you please enlighten me as to how I can resolve the vectors in the x and y-direction like you did at 3:20 and 14:00? Thanks in advance!
As you can see that mg is acting in downward direction,when u draw a line opposite to normal force that line represents the cosine component of mg with angle alpha(when u draw a triangle with mg as opposite side to angle alpha ,u will see that the angle between mg and the side which is in opposite direction to normal force is also alpha),and its sin component is mgsin alpha,that's how the vector mg is resolved.Hope it's clear
Well hello hello, your lectures are absolutely amazing.
Him and Andrew sydllow are excellent teachers!
Sir that assignment link is not working plz anybody help me for that
Know I am curious about the motive for the wheels of the race car being larger.
5:38 Hi sir. I think that it is intuitive that the friction coefficient is independent of the mass of the object. Because if you double the mass, friction will become twice as big, but gravitational force will become twice as big too so the effects cancel out.
I just love physics 💓
Thank you sir, for helping us.
According to me race cars have wide tires so that friction applied on tyres is large and avoids slipping(it has a close relationship with velocity) as it allows friction to act in more area as illustrated in your lecture
I was searching to find a video to help my 2nd year degree s oil m echanics students to understand better the Coloumb's theory (the same French engineer who is also known for the electrical discharge theory) and I've co me across this video. To be very honest, Civil Engineering is nothing but Newtonian Mechanics. We Engineers are applied physicist. Prof ., I really enjoyed your video and will share it with my students if you allow.
of course that is allowed.
At min 7:32 you say that a bit of water on the surface of the plank or of the objects that you are sliding will make the friction coefficient larger. However a larger friction coefficient would make the maximum frictional force acting against the object greater and thus increasing the angle at which the object will start to slide; this is a bit counterintuitive as I would say that with water the surface is more slippery and the object will start to slide at a smaller angle.
So my question is whether you made a mistake, and if instead water on the surface of the plank would make the friction coefficient smaller??,
my plank is made of wood. It's very smooth uniformly sanded. But the wood is not varnished. If you put a drop of water on it locally the friction coeff will go UP. Do not confuse this with hydro-slipping on the road.
ah!!! So if you wet the plank in some point the water will act as a new obstacle opposing to the direction of motion??
it's the wet wood that increases the coeff of friction. The wet fibers of the wood rise. Try it on your own with a piece of bare wood.
Race cars have thicker tires for stability and safety?
Professor Lewin, why are we still driving cars with wheels? Why can't we have hover cars that blow air out of their bottom? What are the difficulties of making such cars? Could you briefly explain and point me to further readings? Thank you!
The fuel consumption needed to hover is MUCH higher than the consumption now.
i would really appreciate if you could answer me this sir Walter lewin; how about the coefficient of static friction for a body moving horizontally and not on an inclined plane
Outstanding! Prof
Thank you for the kind words
The lid on the pan while boiling potatoes is also being lifted by the steam.
i am from india sir and currently studying in class 11th......you teach concepts very nicely thanku so much sir
It's my pleasure
Sir which book you use to teach us? Can you mention the name and price (in USD or Indian National Rupee) ??
8.01
Physics
Hans C. Ohanian
Physics
2nd edition
W.W. Norton & Company
ISBN 0-393-95748-9
8.02
Physics for Scientists & Engineers by Douglas C. Giancoli.
Prentice Hall
Third Edition
ISBN 0-13-021517-18
8.03
Vibrations and Waves by
Anthony French
CRC Press
ISBN 9780748744473
8.03
Electromagnetic Vibrations, Waves and Radiation
by Bekefi and Barrett.
The MIT Press
ISBN 0-262-52047-8
Who's the guy presenting the CO2 device at 43:00 ?
His name Roy Heckler 47:40
If you would have been Indian, you deserved Bharat Ratna. Respect from India!
Sir like you said that air can make objects frictionless, with that reason can we make transportation?
A nice, pleasant lesson ! Thanks !
Sir i am preparing for jee advanced in india and i am very passionate about physics . How can i am study from you. please tell
I ve litterally started lovin physics...
thanks for such beutiful lectures. i enjoy watching them a lot
Glad you like them!
Thank you sir for making physics more understandable!
You are most welcome
Thank you. From 🇿🇦 SA.
how do we calculate the mass of the crete going up hill.
Hello professor Lewin.
I have been working hard this autumn with tension and friction. It is very interesting but sometimes very confusing.
One of the questions in assignment 3, 3:11, about a woman pushing a wooden box of mass 60 kg on a frictionless ramp did me a little confused.
If the ramp was frictionless shouldn’t both the lady and the box sliding down?
Else it wasn’t hard to calculate if I supposed she had super shoes.
>>>If the ramp was frictionless shouldn’t both the lady and the box sliding down?>>
The box is on a frictionless surface, the woman is not.
Thank you for your quick answer.
I have only a few questions two answer now and then I will get my reward.
That is to look at your 10th lecture about Hooke’s Law and Springs.
Thank you so very much for your lectures. I really look forward to see them all.
What was he wearing on his left wrist
Sir, What is origin of normal force?
Pauli's exclusion principle
Or
The restoring force caused by the deformation caused in the surface.
The restoring force caused by the deformation caused in the surface.
@@lecturesbywalterlewin.they9259
Why is there a reforming force? Why do molecules want to regain its position?
One more thing,
How about a book balanced on a vertical nail?
@@Rishabhkumar-gp9tg Pauli's Exclusion Principle is the reason why we can not move our finger through the woden cover of our tables.
@@lecturesbywalterlewin.they9259 Still could not understand the physical origin for that restoring force?
What if we balance a book on a vertically placed nail? The book will also get deformed.
@@Rishabhkumar-gp9tg
The restoring force caused by the deformation caused in the surface.
at 3:30 why x component is mgsin(alpha).... when it is mgcos alpha everywhere
I watched at 3:30, I cannot add to the clarity of that lecture. I decompose the gravitational force, *plain and simple.*
Lectures by Walter Lewin. They will make you ♥ Physics.
x direction component is cos whileas y direction component is sin but here it is opposite......
>>>x direction component is cos whileas y direction component is sin>>>
BIZARRE misconception it depends on the geometry. *Please brush up on your trigonometry and vector decomposition.* en.wikipedia.org/wiki/Vector_decomposition
Lectures by Walter Lewin. They will make you ♥ Physics.
i m red cheeked now but thank you sir.....
there is a great KHAN ACADEMY video about this.you can watch out.
Love you proffessor
Hello Sir. I have a question. If we imagine there is a perfectly frictionless surface, can a man stand still on it, provided that he doesn't exert any horizontal force?
(I think yes)
yes that is possible. Ofcoz she can not walk.
Thanks a lot sir!
@@lecturesbywalterlewin.they9259 exactly same answer as of mine but the thing is I learnt that from u. -.-
47:57 - How do we know that both the masses accelerate in the same magnitude?
I looked at 47:57. There is no mention of masses
Sorry, I meant at 24:41, when you set up the second equation with T and a. The second mass is moving in a different direction than the first mass. What allows us to assume it is moving with the same magnitude of acceleration as the first one?@@lecturesbywalterlewin.they9259
Love you walter you are amazing
I have definitely underestimated the role of friction. Thank you for this great lecture!
You're very welcome!
hello, i want to ask question, i try to solve assignment (35:00) but i couldn't , because i don't know acceleration and static friction , also WALTER LEWIN shows the formula but i dont understand which one (1) or (2)
@Lectures by Walter Lewin, I have watched through the Vedio a lot of times, but I still cannot understand why as the mass increases, the angle it slides down didn't change, because according to the equation: Fmax=muN, as the mass of the object increases, the N must have been also increases, and so mu didn't change, N increases, and so Fmax must increases, this means that it needs more force in order to let in move, as a result the angle should increases in this way of thinking. May you help me to explain the question? Thankyou.
sir you asked why racing car have wide tires. is it due to the fact to reduce the pressure on the tire and also to increase the surface area to increase the heat transfer from it so that the heat generated due to friction do not burn the tires.
I answered you recently already - It's for thermal reasons to radiate the heat away. THe wider the tires the larger is the surface area.
Hello sir, just wanted to say a big thanks for all your work. You are an inspiration for students. By the do you professor HC Verma of IIT Kanpur?
I do not remember having met him
Oh! I just watched one of your iit kanpur video so I asked it, btw many people call him the Walter lewin of India(which is indeed an achievment).
Were your lectures in india recorded and also how was yor experience in my country.
the system of equations at 25:53 is a bit confusing. If the mass hanging on the string is heavier than the object, then how could they have the same acceleration? Is it because as it falls down it losses weight and becomes as heavy as the mass on the incline? If so will the mass on the incline stop accelerating upwards once the mass hanging on the string reaches the same weight ?
An explanation will be HIGHLY appreciated as I think understanding these equations are a big factor in physics, please Walter Lewin, come to my rescue
F=ma
Are you saying that both masses will recive the same acceleration even though they have different masses?
Or should there have been a subscript 2 under the acceleration of mass 2. so the second equation should look like
M2g - T = M2a2 And not M2g -T = M2a because this equation indicates that they get the same acceleration
I cannot add to the clarity of my lecture. If 2 masses are connected by a stiff string the magnitude of their accelerations *MUST* be the same. If not, the string would break.
I am in 9 grade i started facinating about physic and i am studying from our lecture sometime it is little fast but i slow the video and unterstand the concept here my interestin physic is increasing more and more with the increase in knowlege about physic
Greetings from Massachusetts, Why do they say narrow tires perform better in the snow than wide tires?
who are "they"?
I’ve had a few auto technicians tell me that. They would say wide tires act like snow shoes and “float” on snow covered roads and that narrow tires “dig in” like high heeled shoes.
In friction if the objects deform each other then things change. Very large tires will float on top of the snow. Smaller tires push their tread into the snow connecting the two. Ideally you want the largest 'connected' area possible so you can have too big or too small and a lot depends on the speed.
It shows that without out resistance , gravity is not pulling stuff directly to the center of the Earth its more resistance that is directing that .And then equal so there must be a cushion of no resistance were it is purely gravity that governs the track of the Moon around the Earth, which they are floating as such
As per the formula, Fmax is directly proportional to the normal force (which is also dependent on mass) and the coefficient of friction.
So, in the experiment where the two plastic bins were taken, and a mass of 200g was added to one, shouldn't the lighter plastic bin have gone first? As for the lighter plastic bin, the Normal force is less and thus the value of Fmax is less.
I cannot add to the clarity of this lecture. I suggest you watch it again.
11:23 so what's the answer for that? i tried searching on the net but all I could find was that it's related to surface area but then it's clearly not :(
www.quora.com/Does-friction-depend-on-mass
@@lecturesbywalterlewin.they9259 thank you so much! :)
Love the flea circus at the end!!!!
Amazing lectures . Best!!!!!!!! Should I watch 8.01 videos first then 8.02 then 8.03 right ?
Thinking about the car parked on the 45 degree slope:
If size of the tyre (tire) contact patch and mass of the car does not effect the coefficient of friction before the car starts sliding on the slope, why does increasing the size of the contact patch increase the lateral grip of a car going around a corner?
Excluding any downforce etc I dont understand what other factors are at play (and really I should!)
>>>why does increasing the size of the contact patch increase the lateral grip >>>
IT DOES NOT
I believe I have found the answer (or begining of the answer) here:
www.physlink.com/education/askexperts/ae200.cfm
"This is a good question and one which is commonly asked by students when friction is discussed. It is true that wider tires commonly have better traction. The main reason why this is so does not relate to contact patch, however, but to composition. Soft compound tires are required to be wider in order for the side-wall to support the weight of the car. softer tires have a larger coefficient of friction, therefore better traction. A narrow, soft tire would not be strong enough, nor would it last very long. Wear in a tire is related to contact patch. Harder compound tires wear much longer, and can be narrower. They do, however have a lower coefficient of friction, therefore less traction. Among tires of the same type and composition, here is no appreciable difference in 'traction' with different widths. Wider tires, assuming all other factors are equal, commonly have stiffer side-walls and experience less roll. This gives better cornering performance.
Answered by: Daryl Garner, M.S., Physics teacher MacArthur High School, Lawton, OK"
On an unrelated note: Thank you so much for making these videos available. I find them absolutely fascinating and have inspired me to take an interest in mathematics and logical thinking. I really appreciate the effort you have made for us all.
God of physics 👍👍👍😊😊😊😊
17:04 but why?