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!
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.
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
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
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..!! 🙏🙏❤❤❤
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
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.
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 😊
i have a question. If a circular and rectangular body made of same material is put on a plank. Then the circular body will begin to slide at a very low inclination angle but rectangular body will not do so. NOW the value of static friction is independent of area in contact, then why circular body slides at low angle then that of rectangular body.
If you place a circular disc and a rectangular disc made of the same material (same mu) on a plank they will start to slide at the same angle as tan(theta)=mu. Do not confuse sliding wit rolling. The circular disk should SLIDE. You should therefore place the flat part of the disc on the plank.
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.
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
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!
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
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
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)
there was this jee adv question(2010) where they asked to select the graph of force vs friction as one changes force on a block on inclined plane.Thanks to your lecture that i now have the concept to tackle the problem.
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
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 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 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..
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 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..
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.
Sir what about rolling friction?? Is it different from the kinetic one.. I came across a inequality which states that mu(s) is greater than mu(k) which is greater than mu(r)..
Hello Sir! I had a question. After the applied force is greater than the maximum frictional force we get some accelerations (in flat ground scenarios). But from the graph of frictional force vs applied force we see that the curve droops a bit before frictional force becomes constant that is mu(kinetic)*normal reaction force. So in this drooping portion does it mean as we increase applied force the kinetic frictional force decreases? I know its quite obvious but never heard about this before. Help please!
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
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)
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.
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
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
sir what could be the acceleration of the carbondioxide disk when the flea was pulling it? I mean the mass was considerable , and then the flea cant exert much force, so is it okay for us to conclude that acceleration was much less than 1
A flea has a mass of about 1 milligram. We know fleas can walk upside down on the ceiling, because their feet can grip the surface through arthropod adhesion. Assuming arthropod adhesion could enable the flea to pull with a traction force of 10 times its body weight, this would mean that it is pulling with 100 micronewtons of force If the CO2 vessel has a mass of 500 grams, this would mean that the flea could pull it at an acceleration of 200 microns/second^2.
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.
My thoughts nearly exactly Hahaha Nearly ;) Good job And the man's gauntlet on his wrist is true as is necessary for the amount of amazing knowledge he has
@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.
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)
Dear sir, Racing car have wider tyres for heat dissipation. If so then what is the consequences of over heating in tyres?. expecting a favourable reply from u sir.
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
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
Amazing lecture. I have two questions: 1) Ok, I agree that μ = tan θ is independent of the mass. But, maximum static friction force is still Fm = μ x N = tan θ x mg x cos θ = mgxsinθ, which is a function of the mass. So, for m2>m1, we have that the Fm2 > Fm1 and the body 2 would fall latter thatn body 1. 2) I agree that the formula tells nothing about the area. But, what if we have a spherical object and a box with the same material both on the inclined plane. How on earth the spherical one will not fall earlier? thanks.
The angle at which any object with static friction coeff mu starts to slide is independent of the mass. The maximum friction is mu*N which is obviously mass dependent (the larger the mass the larger N). But that is irrelevant. If you have 2 objects one with mass m1 and the other with mass m2 both with the same friction coeff mu then they will start to slide at THE SAME angle theta_slide as tan(theta_slide)=mu. Your conclusion is not correct.
Prof. 9:48 why they were not moving at the same time?? Is it due to the normal force? Because due to the addition of masses to one crate The normal increase and static friction is equal to the product of normal and mu(s) here mu(s) is constant but the normal increases So the massive one move down early Is this explanation true?
Sir, how do you move the board upward and downward and as well as keep it stationary while writing on it?( Yes it can be seen that the board is slightly moving down while you are writing on it, but still its mostly stationary)
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.
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 friction force is dependent on the mass of the object ,f=N*coeff. so at 9:30 min. of the lecture when you use two identical bins but one of them is larger mass , and you say they should move at the same angle , but lam wondering did the bin with larger mass has more frictional force ( f=N*coeff) so it should move later ?
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.
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)
Hello, Sir. I have a question. (4:59) Is your max. frictional force and gravitational force in the x direction always positive? If it is not, shouldn't action=minus reaction, not action=reaction?
Not at all. That equation uses the fact that ∑ F = 0 along the surface of the incline (as we're talking about static friction ; a = 0) mgsin(α) - F(max) = 0
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!
THIS IS PROBABLY THE BEST LECTURE ON FRICTION THAT I'VE WATCHED IN MY LIFE SO FAR.
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
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
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?
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
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.
:)
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
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..!! 🙏🙏❤❤❤
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
one of the best PHYSICS TEACHER EVER BEEN !! GREAT!
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!
Amazing professor, this is helping a lot for my technical physics exam as a chemE student.
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.
U r my favourite physics teacher from now...bravo 👏 👏
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
Congratulations, Professor Lewin! May you have good health and a long life! To celebrate your birthday, I am watching this magnificent lecture. 🎊🎊🎊🎉🎉
i have a question.
If a circular and rectangular body made of same material is put on a plank. Then the circular body will begin to slide at a very low inclination angle but rectangular body will not do so. NOW the value of static friction is independent of area in contact, then why circular body slides at low angle then that of rectangular body.
If you place a circular disc and a rectangular disc made of the same material (same mu) on a plank they will start to slide at the same angle as tan(theta)=mu. Do not confuse sliding wit rolling. The circular disk should SLIDE. You should therefore place the flat part of the disc on the plank.
Lectures by Walter Lewin. They will make you ♥ Physics. thankyou sir
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.
Great lecture and wonderful demonstrations 😊
The ending was really COOL!
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 .
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
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
:)
This is actually very awesome I now feel physics as stress reliever and mind fresher
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!
We are very lucky to have a teacher like u..... 😊
You make my day sir ❤️🤞🏻
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
U are best professor of physics literally your vidoes make me fall in love with physics❤
The most entertaining lecture on fiction, ever!
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
Professor W.L explained very well. I didn't understand when I took Newtonian Physics in my freshman year. Thank you Professor!
:)
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 ?
Best of the best lectures....I happened to dwell in it....
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)
C'est toujours un plaisir de revoir aussi cette video ....Ca parait tellement facile
Him and Andrew sydllow are excellent teachers!
there was this jee adv question(2010) where they asked to select the graph of force vs friction as one changes force on a block on inclined plane.Thanks to your lecture that i now have the concept to tackle the problem.
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
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 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 😂😂😂
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..
A nice, pleasant lesson ! Thanks !
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 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
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.
Thank you so much, sir. You really helped me a lot with sat 2 subject
Thank you sir, for helping us.
I ve litterally started lovin physics...
Thank you sir for making physics more understandable!
You are most welcome
thanks for such beutiful lectures. i enjoy watching them a lot
Glad you like them!
Sir what about rolling friction?? Is it different from the kinetic one.. I came across a inequality which states that mu(s) is greater than mu(k) which is greater than mu(r)..
Hello Sir! I had a question. After the applied force is greater than the maximum frictional force we get some accelerations (in flat ground scenarios). But from the graph of frictional force vs applied force we see that the curve droops a bit before frictional force becomes constant that is mu(kinetic)*normal reaction force. So in this drooping portion does it mean as we increase applied force the kinetic frictional force decreases? I know its quite obvious but never heard about this before. Help please!
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
thank you professor, i loved the air track experiment....
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)
i am from india sir and currently studying in class 11th......you teach concepts very nicely thanku so much sir
It's my pleasure
Well hello hello, your lectures are absolutely amazing.
Love you walter you are amazing
The flea circus is funny ,but the fleas are disgusting lol
I just love physics 💓
Love you proffessor
Sir like you said that air can make objects frictionless, with that reason can we make transportation?
Flea circus! hahaha
Genius teacher.
THANKYOU SIR FOR MAKING PHYSICS MORE UNDERSTANDABLE FOR ME ❤️❤️ 🤗
A BIG THANKS FROM INDIA ❤️🙏
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.
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
My aim to complete bsc honours in physics this video is very helpful
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
sir what could be the acceleration of the carbondioxide disk when the flea was pulling it? I mean the mass was considerable , and then the flea cant exert much force, so is it okay for us to conclude that acceleration was much less than 1
A flea has a mass of about 1 milligram. We know fleas can walk upside down on the ceiling, because their feet can grip the surface through arthropod adhesion. Assuming arthropod adhesion could enable the flea to pull with a traction force of 10 times its body weight, this would mean that it is pulling with 100 micronewtons of force
If the CO2 vessel has a mass of 500 grams, this would mean that the flea could pull it at an acceleration of 200 microns/second^2.
Started loving physics
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 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.
My thoughts nearly exactly
Hahaha
Nearly
;)
Good job
And the man's gauntlet on his wrist is true as is necessary for the amount of amazing knowledge he has
@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.
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)
Thank you. From 🇿🇦 SA.
how do we calculate the mass of the crete going up hill.
Dear sir,
Racing car have wider tyres for heat dissipation. If so then what is the consequences of over heating in tyres?. expecting a favourable reply from u sir.
Rubber will melt, melting rubber loses grip
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
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
Amazing lectures . Best!!!!!!!! Should I watch 8.01 videos first then 8.02 then 8.03 right ?
Thanks you sir such a explaination . Love from india 💖✨
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
Amazing lecture. I have two questions:
1) Ok, I agree that μ = tan θ is independent of the mass. But, maximum static friction force is still Fm = μ x N = tan θ x mg x cos θ = mgxsinθ, which is a function of the mass. So, for m2>m1, we have that the Fm2 > Fm1 and the body 2 would fall latter thatn body 1.
2) I agree that the formula tells nothing about the area. But, what if we have a spherical object and a box with the same material both on the inclined plane. How on earth the spherical one will not fall earlier?
thanks.
The angle at which any object with static friction coeff mu starts to slide is independent of the mass. The maximum friction is mu*N which is obviously mass dependent (the larger the mass the larger N). But that is irrelevant. If you have 2 objects one with mass m1 and the other with mass m2 both with the same friction coeff mu then they will start to slide at THE SAME angle theta_slide as tan(theta_slide)=mu. Your conclusion is not correct.
Love the flea circus at the end!!!!
Prof. 9:48 why they were not moving at the same time??
Is it due to the normal force?
Because due to the addition of masses to one crate
The normal increase and static friction is equal to the product of normal and mu(s) here mu(s) is constant but the normal increases
So the massive one move down early
Is this explanation true?
Know I am curious about the motive for the wheels of the race car being larger.
Sir, how do you move the board upward and downward and as well as keep it stationary while writing on it?( Yes it can be seen that the board is slightly moving down while you are writing on it, but still its mostly stationary)
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.
Flea circus was just amazing
what is the thing that you are wearing in your hand sir?
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.
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!
The lid on the pan while boiling potatoes is also being lifted by the steam.
the friction force is dependent on the mass of the object ,f=N*coeff. so at 9:30 min. of the lecture when you use two identical bins but one of them is larger mass , and you say they should move at the same angle , but lam wondering did the bin with larger mass has more frictional force ( f=N*coeff) so it should move later ?
The acceleration, a, down the incline is given by the following equation: mg*sin(theta) -- mu*mg*cos(theta)=ma.
m cancels.
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. 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. -.-
Sir I want to ask you that "Fundamental of physics by Rensick haliday" book is good for learning concept or not ?
its ok
Thank you😊
Hello, Sir. I have a question. (4:59) Is your max. frictional force and gravitational force in the x direction always positive? If it is not, shouldn't action=minus reaction, not action=reaction?
Not at all. That equation uses the fact that ∑ F = 0 along the surface of the incline (as we're talking about static friction ; a = 0)
mgsin(α) - F(max) = 0