@noelleleger232 *WRONG* if the only force acting on an object is gravity, then it is in free fall and it will have no weight! But ofcoz due to the gravitational force it may change both speed and also direction. If a planet is in a circular orbit, its speed does not change but the gravitaional force keeps it in orbit. Called centripetal force. All this is covered in my 8.01 lectures. *All this is very very ellementary high school Physics*
I have a doctorate in physics from the University at the other end of Mass Ave. I am watching these because he is so much fun to watch. With my experience I keep thinking these are too simple for MIT students, but then I think about it, and no these _physics_ lectures, and physics is the most crunchy of the hard sciences, so the intro physics lectures cover the same material at every university in the world.
Dear professor Lewin (WL). your lectures are just wonderful. You planned the lectures in a highly professional manner. I noticed how clever you are in dividing the presentation into segments that make so much sense, I mean the order of events, whether you start with a formula(F), a video(V), or a practical experiment(Pe), it helps us understand the complicated issues with ease. We know how much you really love physics. My mother always told me: "Believe in yourself, and others will believe in you" - After watching you, we believe in you and we love physics(LP). Thanks! -- LP = WL(Pe+V+F)/t ---obviously, measured in Lewins.
@noelleleger232 *WRONG* if the only force acting on an object is gravity, then it is in free fall and it will have no weight! But ofcoz due to the gravitational force it may change both speed and also direction. If a planet is in a circular orbit, its speed does not change but the gravitaional force keeps it in orbit. Called centripetal force. All this is covered in my 8.01 lectures. *All this is very very ellementary high school Physics*
Prof Lewin is defining weight as the force that opposes the gravitational force, if any, from whatever source it comes. Whether it is from a string, the floor, or a scale in the bathroom. But these guys in Aeronautics call their experiments 'zero gravity', and I think they are not being disingenuous or careless. There's a case to call it zero gravity. In the ref frame of the free falling body, there's no way you can prove that any gravity exists. Just like in the Galileo experiment with the observer in the cabin of a ship, where he could never prove that there is a speed, a laboratory full of physicists in free fall, even with Prof Lewin inside it (God forbid!) they would never be able to proof that there is any gravity. Of course, they would not have time to publish their (negative) result 😢😅 The conclusion would be, since the laws of physics must be the same for all observers, not only the inertial ones, that for that free falling unfortunates, there is no gravity. There are some interesting, not well understood issues here that could be highlighted by some thought experiments.
@davidmudry5622 You're right ! In free fall, there is no force.. because (or rather 'therefore') there is no gravity. The question then would be - from the 2nd law, there must be a force since you are changing velocity ! What is the way out? I suspect there's a nice answer to this that violates neither the 2nd law nor the 3rd !
@davidmudry5622There is a reaction. When you look for a reaction you need to look on the second body that interacts. In the case of gravity, the force appears due to the gravitational interaction between the planet earth and the object that is falling. The action is on the object and the reaction is on the planet earth. Proffesor Lewin covered this in Lecture 6.
Prof. Lewin: You are a gifted and inspiring teacher! You've performed a great service by posting these lectures for those unfortunate enough to have not seen and learned from you in person.
0:20 introduce bathroom scale and elevator scale (3 cases/ decelerate, accelerate, weightless - result when a=g free-fall) + example 9:30 example roller + (tension - spring massless) + explain the result + prediction ( similar: elevator scale) 20:45 experiment around a circle (ac) (similar elevator scale) 25:50 weightless ex with a bucket of water (such amazing) (4 phases of this cases: normal weight, weightless, increase weight, normal weight) 34:40 an experiment with a device By Pro. Dave + a graph show u is incredible / physics here 39:35 zero gravity experiment (zero weight/ zero gravity) - airplane - sickness 47:25 video about weightlessness/ take risk for the future of science and technology
I'm totally in love with physics now, it's 3:26 am here btw and I don't wanna sleep listening to this lectures, and i can only imagine how my life could have been as having a teacher like you in my highschool days, you're so good Sir.
I'll never get over those dotted lines. Brilliant in so many ways, sandals and socks jumping off desks, the madman. These lectures deserve a round of applause at the end. It used to be customary.
@noelleleger232 *WRONG* if the only force acting on an object is gravity, then it is in free fall and it will have no weight! But ofcoz due to the gravitational force it may change both speed and also direction. If a planet is in a circular orbit, its speed does not change but the gravitaional force keeps it in orbit. Called centripetal force. All this is covered in my 8.01 lectures. *All this is very very ellementary high school Physics*
I am a doctor of liver and stomach - absolutely no relation with these topics, but trust me I've enjoyed it alot. I wish someone would've taught it this way in our college days. Back then, physics seem to be an imaginable subject and everytime it would start with, "let's suppose this". But watching these videos, it makes alot of sense and these students are lucky. A subject that was considered boring, has made so much interesting by Prof that a medical doctor is watching it - for HOURS! KUDOS to you sir.
I have been struggling with understanding gaining or loosing weight in an elevators for 1.5 years. Now it's all clear to me just because of your brilliant ability to teach and my imagination. You are a great teacher. A great teacher's success does not lie in teaching his students, but making sure they attain it. And you have that. Thank you professor Lewin, you have helped me so much!
Well, I didn't know that you have your lectures on UA-cam and this UA-cam page is managed none other than you! Walter Lewin your way of teaching is extraordinary. You just don't tell us the bookish stuff, but also tell us how it works practically and that's fascinating. I was confused about this topic and many others, but now I can't say that anymore, I just found about your lectures yesterday and I think I am going to love physics now. Thank you :)
I loved physics but my physics professor made me hate it because he goes so slow and is uncharamatic, but I go here and he reminds me why I like be physics
I am a retired university psychology professor. I love watching UA-cam videos on physics, especially quantum mechanics and cosmology. After discovering Dr. Lewin's lectures I admire his true teaching genius. Thank you professor Lewin.
i wish i had such good professors when i was young .... , i am 42 years old and i just love waching and learning .... you Professor Walter Lewin are indeed a treasure,
The way you explain is amazing, The weightlessness is indeed amazing, I wish I was born earlier(I am 17 though) to be a part of your lecture in person... I really think that I missed a lot professor. You are Beyond Awesome, So far So good. I wish you live 100 years more!!
This professor is the antithesis of the (in my opinion unfair and insulting) parable that "Those that can,do and those that can't - teach". It takes additional levels of excellence to be able to explain difficult concepts with such clarity, yet in way that inspires curiosity. The amount of lives and careers one excellent teacher can influence is incredible - it propagates, like waves in water, one group of minds shaping another, all inspiration emanating from one person. We need to appreciate teachers, or we'll all loose.
Hello Pf. Lewin. You are a life-changing professor. Im a spanish Physics sutdent in the UK. I want to be a teacher when I grow up. With corona, online classes got boring and unappealing. With your lectures I feel provoked to learn and think, and remind me why Im studying this degree. Furthermore, I would like to someday be able to teach in this engaging and passionate way. Thanks for everything ;) Ramon
Professor Walter Lewin, watching your videos is like watching a Sci-Fi movie. Incredible facts that I had never realized before. How amazing is how the world works! These lectures are a treasure and I´m very lucky to have discovered them. Thanks for sharing them.
Dear sir, I am astonished by your method of explanations. These are very clear and lucid. I have been explaining the physical phenomenon in a similar manner. I am a solar cell scientist with a PhD in Physics on SIS type of Si Solar cells from IIT Delhi, India. I have already spent about 40 yrs in R&D in India. I would love to be associated with a personality like you. I will see all your lectures on you tube. I salute you for clear understanding of Physics concepts.
Im from Argentina and i course in a good public university, but when i see this video and this professor i get excited. Professor you are incredible, thank you so much.
Lewin sir, this was my first time when I PRACTICALLY learned the varying cases and weightlessness ( as shown in the video ). Last year, in class 11, went through books, understood nothing. In this lecture, within less than an hour, you just made it simple and practical and UNDERSTANDABLE . Wonderful !
While watching your soothing lectures over and over I found a very fascinating visualization of accelerating objects. When you make a dotted line I notice that the line itself a mind blowing example of such kind. When the gaps between successive points increases it's accelerating (mainly the first half of the line) and reverse for deceleration (the last half) . And for constant gaps its 0 acc. I use this fact by showing your videos to my friends...for them to understand and visualize the beauty of accelerating bodies. You are really an inspiration for my love of physics. ❤
Thank your Lewin. Your explanations are so clear and experimental, that to go through this course, one does not even need to take a pen and paper. Just following along is more than enough. Thank you.
Walter I would like to thank you for the wonderful lectures. I have watched all your lectures and my favourite lecture that I consider the most enlightening is 16 part of 8.02 about electromagnetic induction. I'm a final year electrical engineering student from canada. Cheers!
Was Dave a student, He's really smart. And also do MIT profs have dinner with the students! If that's the case, that's how the relation between a student and a teacher should be. All your students around the world love you.
David Pooley was my graduate student in 1999 when I gave these lectures. He is now a Professor in the US. He is very bright and also an outstanding teacher. He got a teaching award at MIT.
Sir for sure I think physics is taught in a really bad way but now I am sure in future I will try to be a proffessor like you I am loving your lectures and these are so beautifully arranged that the concept becomes crystal clear Really I am in ❤️ with physics now
Wat een verschil van lesgeven met mijn lesgevers 50 jaar terug in België. Ik hou van uw stijl en humor en engagement. Je geeft geen les fysica, je bent het!
Excellent lecture & demos! 45:16 - a couple of suggest for improvement... There is a disconnect in terminology. The slide is actually accurate when it states "2g" & "0g". It needs to be understood that pilot language is being used here, like when it is said that an F-16 is pulling 9g's. Here "g" is referring to total acceleration, meaning the acceleration due to gravity _plus_ aerodynamic acceleration forces. The acceleration scale that pilots use sets "1g" equal to the acceleration due to gravity at the Earth's surface, so that's why they use the letter "g". The disconnect in terminology here is because the same letter is being used by different people to mean different things. Prof uses it to mean accel due to gravity, whereas the slide uses it as a scale for the measured total acceleration. Another statement that needs to be addressed from that same point in the video: "The engine is restarted." I expect everyone is clear that the engines were never _stopped_ at any point during the flight. So what is really meant by "restarted" is that the thrust level is increased. During the parabola, the engine thrust level is set to only counteract aerodynamic drag. The net result of this engine thrust is such that the flight path and velocity would be as close as possible to the trajectory if it were to have happened if there was no atmosphere at all, like a spaceship would experience. During the 2g pullout, a lot more thrust is needed, so the throttles are pushed up at that point. In the big picture, my points of feedback here are minor. Overall this lecture is amazing! And it would be great if NASA were to be so clear and precise in explaining what weightlessness is and what it isn't.
Sir Your teaching style is amazing.I am now fan of you.thanks to youtube and thanks to you sir to give us these opportunity.Thanks a lot sir.This is my first public comment.please reply sir.I shall be greatful.
Professor, I had a question. If you would answer this, I will be very grateful.The question is: An object is in free fall when the force acting on it is exclusively gravitational. But why then the moon is in free fall? Isn't there centrifugal force acting on it? I will be very grateful to you to know the answer. You have given me new eyes of physics to see the world. You've really made me love physics. Thanks professor. Lots of love.
Earth is in free fall - grav attraction of the sun is the centripetal force to keep the Earth in orbit. Moon is in freefall grav attraction of the Erath is the centripetal force to keep the Moon in orbit.
@@lecturesbywalterlewin.they9259 But does the centrifugal force act on the moon? If yes, how can we say that it's in free fall? I will be highly obliged if you'll clear my doubts on the topic. Thanks.
if only gravitational froces act on an object it is in free fall. That's the defintiion of free fall. The only forces on the ISS are gravitational forces; this the ISS is in free fall. If you jump off the table the only force that acts on you is gravity thus you are in free fall.
@@arctic215 The centrifugal pseudoforce is a fictitious force, as a consequence of solving the problem in an accelerating reference frame. This is why it is a pseudoforce, rather than a real force. If you use an inertial reference frame to examine the forces acting upon the moon in orbit around the Earth, there is no centrifugral pseudoforce term. The moon is in free fall around the Earth, because no real force other than gravity acts upon it to make it orbit.
If the rope is considered massless and all pulleys are considered frictionless, then the tension is uniform throughout the rope. The pulley simply reverses the direction of the tension.
Take 2 different points on a rope and say tensions at those points are T1 and T2 respectively. Let the mass of rope between them be assumed to be "m". For accelerating rope along T1. We have, T1-T2=ma, But for a massless string m is considered as 0. Implies T1 must be equal to T2. Edit: Thus a constant tension T=T1=T2... on every point on string.
i am just thinking . when it was recorded just curious. He is looking young . But alas one day everyone have to go. btw love u sir ,i hope u live long.
@@lecturesbywalterlewin.they9259 Well, the see-saw look alike for Tension example when both are equal.. Also Now Superman in weightlessness can get extreme sickness.
I think I am doing something wrong in calculating the time for an airplane to reach it's peak at 42:56 Instead of getting 15 seconds, I am getting 30 seconds Here is what I am doing : ( Considering the motion in y direction only ) The V , final velocity in y direction is zero at it's peak so V = 0 m/s , u = 300 m /s , a=-g = -10 m/s^2 To calculate t , I will put the above values in equation V= u+ at ; 0= 300+(-10*t) ; -300 = -10*t ; 30= t Where am I wrong ?
I forgot to convert the velocity into m/s from miles per hour :( Sir , Awesome Lecture though ..couldn't have understood weightlessness before but things are making much more sense now 😌
"6 times less"? My physics prof would have skewered me if I said "times less". He almost broke 2 of my fingers for arguing with him in class. Great guy.
I enjoy everything about physics especially the simple algebra at 15:00 that is used. I got lost though how was the a for acceleration isolated to provide the new equation of a=msub2-msub1/msub1+msub2 g?
Thank you Sir. Your lectures really made me understand Physics better for my JEE Advanced Exam. And a doubt, is the motion sickness caused while traveling through waters also because of the change in weight due to buoyancy??
No. Buoyancy supports the boat, but the motion sickness is independent of what its cause the motion. Your weight does not change due to buoyancy, but due to the up and down motion of the boat.
Fantastic lecture. However, when it comes to the parabolic airplane problem beginning at 41:20 I am unsure how you calculated that the airplane would reach its sommet in 15 seconds since it has a speed of 300m/s and the only force acting against it is gravitational acceleration at 10m/s^2 which brings the sommet to 30 seconds rather than 15. Again, awesome lecture.
A Question. 30:18 so when a plane is landing then the passengers weight should be gained tremendously. Shouldn't this cause a problem due to increase in weight??
Pilots try to approach the landing runway at a very gradual descent, such that vertical accelerations are reduced as much as practical, so that the landing gear is capable of supporting the touch-down forces. The aircraft engineers who designed the landing gear know about this issue, and have accounted for the increase in apparent weight when the plane touches down. This is also why pilots have to dump fuel, when necessary to make an emergency landing. The mass of an airplane at takeoff is significantly greater than the landing mass, after accounting for the expected amount of fuel to be burned if the plane makes it all the way to the destination. When they have to make an emergency landing after only having burned a small fraction of their fuel, the plane will weigh more than the landing gear can withstand. The pilot has to release unburned fuel in mid-air, in order to make the unplanned landing safely.
In Jr high school my science teacher made "runner up" in the "teacher in space" program. We viewed this type of video several times. We viewed the space shuttle Challenger destroyed. I commented on it's explosion, and received a severe reprimand for it, followed by a sincere apology later on. His hands were shaking for a couple of days, as he was realizing it would have been himself... It's true...
at 15:17 is m m1 or m2 in the equation T=2mg/(m1+m2) ? I substituted a in equation 1 and got T=(2m_1 * m_2 * g) / (m_1+m_2) can some one tell me what I did wrong? Edit: never mind the professor corrected it
How did he derive the equation T = 2m1m2g/(m1+m2)? I substituted acceleration into the earlier equations and that's not what I got at all. I imagine I am missing some simple algebra but I get stuck no matter which way I go about it.
The scale cannot measure true gravity. It can only measure the constraint force it applies to its pan and the load. When it is free falling, there is zero constraint force between its components, and thus it measures zero.
If we had a teacher like you i think we could have been in love with Physics from the beginning!
Thank you so much for this!
You are a great man!
Thank you Gabriel
@davidmudry5622maybe if you take g as a constant it could solve your problem
@noelleleger232 *WRONG* if the only force acting on an object is gravity, then it is in free fall and it will have no weight! But ofcoz due to the gravitational force it may change both speed and also direction. If a planet is in a circular orbit, its speed does not change but the gravitaional force keeps it in orbit. Called centripetal force. All this is covered in my 8.01 lectures. *All this is very very ellementary high school Physics*
The reaction of this force is on the Earth by the free falling object.
I have no need for these lectures in terms of university/exams yet these lectures are still a joy to watch. What a professor Walter Lewin is.
now you are not studying,you are learning !
I have a doctorate in physics from the University at the other end of Mass Ave. I am watching these because he is so much fun to watch. With my experience I keep thinking these are too simple for MIT students, but then I think about it, and no these _physics_ lectures, and physics is the most crunchy of the hard sciences, so the intro physics lectures cover the same material at every university in the world.
Dear professor Lewin (WL). your lectures are just wonderful. You planned the lectures in a highly professional manner. I noticed how clever you are in dividing the presentation into segments that make so much sense, I mean the order of events, whether you start with a formula(F), a video(V), or a practical experiment(Pe), it helps us understand the complicated issues with ease. We know how much you really love physics. My mother always told me: "Believe in yourself, and others will believe in you" - After watching you, we believe in you and we love physics(LP). Thanks! -- LP = WL(Pe+V+F)/t ---obviously, measured in Lewins.
thanks for your kind words
@noelleleger232 *WRONG* if the only force acting on an object is gravity, then it is in free fall and it will have no weight! But ofcoz due to the gravitational force it may change both speed and also direction. If a planet is in a circular orbit, its speed does not change but the gravitaional force keeps it in orbit. Called centripetal force. All this is covered in my 8.01 lectures. *All this is very very ellementary high school Physics*
Prof Lewin is defining weight as the force that opposes the gravitational force, if any, from whatever source it comes. Whether it is from a string, the floor, or a scale in the bathroom.
But these guys in Aeronautics call their experiments 'zero gravity', and I think they are not being disingenuous or careless. There's a case to call it zero gravity. In the ref frame of the free falling body, there's no way you can prove that any gravity exists. Just like in the Galileo experiment with the observer in the cabin of a ship, where he could never prove that there is a speed, a laboratory full of physicists in free fall, even with Prof Lewin inside it (God forbid!) they would never be able to proof that there is any gravity.
Of course, they would not have time to publish their (negative) result 😢😅
The conclusion would be, since the laws of physics must be the same for all observers, not only the inertial ones, that for that free falling unfortunates, there is no gravity.
There are some interesting, not well understood issues here that could be highlighted by some thought experiments.
@davidmudry5622
You're right ! In free fall, there is no force.. because (or rather 'therefore') there is no gravity.
The question then would be - from the 2nd law, there must be a force since you are changing velocity ! What is the way out?
I suspect there's a nice answer to this that violates neither the 2nd law nor the 3rd !
@davidmudry5622There is a reaction. When you look for a reaction you need to look on the second body that interacts. In the case of gravity, the force appears due to the gravitational interaction between the planet earth and the object that is falling. The action is on the object and the reaction is on the planet earth. Proffesor Lewin covered this in Lecture 6.
I love his phrase "Non negotiable"
Niotech ..............?
@@rajaradi802 he ends any fact with that phrase "non - negotiable"
the reason why you love the phrase is because you find it interesting, that is NON NEGOTIABLE
200th
@@hetaeramancer lmao
Prof. Lewin: You are a gifted and inspiring teacher! You've performed a great service by posting these lectures for those unfortunate enough to have not seen and learned from you in person.
0:20 introduce bathroom scale and elevator scale (3 cases/ decelerate, accelerate, weightless - result when a=g free-fall) + example
9:30 example roller + (tension - spring massless) + explain the result + prediction ( similar: elevator scale)
20:45 experiment around a circle (ac) (similar elevator scale)
25:50 weightless ex with a bucket of water (such amazing) (4 phases of this cases: normal weight, weightless, increase weight, normal weight)
34:40 an experiment with a device By Pro. Dave + a graph show u is incredible / physics here
39:35 zero gravity experiment (zero weight/ zero gravity) - airplane - sickness
47:25 video about weightlessness/ take risk for the future of science and technology
Thankyou
@davidmudry5622 how would this dude know
I'm totally in love with physics now, it's 3:26 am here btw and I don't wanna sleep listening to this lectures, and i can only imagine how my life could have been as having a teacher like you in my highschool days, you're so good Sir.
Best of luck!
I'll never get over those dotted lines.
Brilliant in so many ways, sandals and socks jumping off desks, the madman.
These lectures deserve a round of applause at the end. It used to be customary.
thanks for your kind words
@noelleleger232 *WRONG* if the only force acting on an object is gravity, then it is in free fall and it will have no weight! But ofcoz due to the gravitational force it may change both speed and also direction. If a planet is in a circular orbit, its speed does not change but the gravitaional force keeps it in orbit. Called centripetal force. All this is covered in my 8.01 lectures. *All this is very very ellementary high school Physics*
These students are very fortunate to have such a passionate lecturer .
I am a doctor of liver and stomach - absolutely no relation with these topics, but trust me I've enjoyed it alot. I wish someone would've taught it this way in our college days.
Back then, physics seem to be an imaginable subject and everytime it would start with, "let's suppose this". But watching these videos, it makes alot of sense and these students are lucky. A subject that was considered boring, has made so much interesting by Prof that a medical doctor is watching it - for HOURS! KUDOS to you sir.
It's gretat that you watch my lectures; many medical doctors are watching my lectures.
You'reperfectly right
I have been struggling with understanding gaining or loosing weight in an elevators for 1.5 years. Now it's all clear to me just because of your brilliant ability to teach and my imagination. You are a great teacher. A great teacher's success does not lie in teaching his students, but making sure they attain it. And you have that. Thank you professor Lewin, you have helped me so much!
Well, I didn't know that you have your lectures on UA-cam and this UA-cam page is managed none other than you! Walter Lewin your way of teaching is extraordinary. You just don't tell us the bookish stuff, but also tell us how it works practically and that's fascinating. I was confused about this topic and many others, but now I can't say that anymore, I just found about your lectures yesterday and I think I am going to love physics now. Thank you :)
Thanks Batman for your kind words
Lectures by Walter Lewin. They will make you ♥ Physics. Oh! You really replied.Well, it's my pleasure sir.
Who wouldn't reply to Batman
I loved physics but my physics professor made me hate it because he goes so slow and is uncharamatic, but I go here and he reminds me why I like be physics
@@lecturesbywalterlewin.they9259
Hey wasssuupp
I am a retired university psychology professor. I love watching UA-cam videos on physics, especially quantum mechanics and cosmology. After discovering Dr. Lewin's lectures I admire his true teaching genius. Thank you professor Lewin.
:)
i wish i had such good professors when i was young .... , i am 42 years old and i just love waching and learning .... you Professor Walter Lewin are indeed a treasure,
I free fall in Love with physics by seeing this kind of lecture
The way you explain is amazing, The weightlessness is indeed amazing, I wish I was born earlier(I am 17 though) to be a part of your lecture in person... I really think that I missed a lot professor. You are Beyond Awesome, So far So good. I wish you live 100 years more!!
This professor is the antithesis of the (in my opinion unfair and insulting) parable that "Those that can,do and those that can't - teach". It takes additional levels of excellence to be able to explain difficult concepts with such clarity, yet in way that inspires curiosity. The amount of lives and careers one excellent teacher can influence is incredible - it propagates, like waves in water, one group of minds shaping another, all inspiration emanating from one person. We need to appreciate teachers, or we'll all loose.
I’m obsessed with these lectures. On my 2nd go round of 8.01 and each time it makes more sense and becomes that much more elegant.
:)
Hello Pf. Lewin. You are a life-changing professor.
Im a spanish Physics sutdent in the UK. I want to be a teacher when I grow up. With corona, online classes got boring and unappealing. With your lectures I feel provoked to learn and think, and remind me why Im studying this degree. Furthermore, I would like to someday be able to teach in this engaging and passionate way. Thanks for everything ;)
Ramon
27:16 This is the best physics teacher I`ve ever seen, And I had a couple of great ones while in university.
At the 30 min mark you can just tell he was on fire!
In the flow of teaching
:)
Professor Walter Lewin, watching your videos is like watching a Sci-Fi movie. Incredible facts that I had never realized before. How amazing is how the world works! These lectures are a treasure and I´m very lucky to have discovered them. Thanks for sharing them.
Wow, thanks!
Dear sir, I am astonished by your method of explanations. These are very clear and lucid. I have been explaining the physical phenomenon in a similar manner. I am a solar cell scientist with a PhD in Physics on SIS type of Si Solar cells from IIT Delhi, India. I have already spent about 40 yrs in R&D in India. I would love to be associated with a personality like you. I will see all your lectures on you tube. I salute you for clear understanding of Physics concepts.
Im from Argentina and i course in a good public university, but when i see this video and this professor i get excited. Professor you are incredible, thank you so much.
After watching ur videos I started understanding physics and now I am highly attracted towards it ..
i just discovered that i'm in love with physics thanks to your lectures, thank you Professor Walter Lewin, greetings from Indonesia
You are very welcome
Lewin sir, this was my first time when I PRACTICALLY learned the varying cases and weightlessness ( as shown in the video ).
Last year, in class 11, went through books, understood nothing.
In this lecture, within less than an hour, you just made it simple and practical and UNDERSTANDABLE .
Wonderful !
While watching your soothing lectures over and over I found a very fascinating visualization of accelerating objects. When you make a dotted line I notice that the line itself a mind blowing example of such kind. When the gaps between successive points increases it's accelerating (mainly the first half of the line) and reverse for deceleration (the last half) . And for constant gaps its 0 acc. I use this fact by showing your videos to my friends...for them to understand and visualize the beauty of accelerating bodies. You are really an inspiration for my love of physics. ❤
Thank your Lewin. Your explanations are so clear and experimental, that to go through this course, one does not even need to take a pen and paper. Just following along is more than enough. Thank you.
Walter I would like to thank you for the wonderful lectures. I have watched all your lectures and my favourite lecture that I consider the most enlightening is 16 part of 8.02 about electromagnetic induction. I'm a final year electrical engineering student from canada. Cheers!
yes, lecture 16 is an eye-opener EVEN for many physics teachers!
You are brilliant, entertaining, and a great teacher. Thank you for your lectures.
I was amazed to see the magic of physics in this lecture. You've done such a good job sir 👍.
Keep watching
Yes u r right👍
To be honest best Physics professor I have seen
Love & respect for you, Prof. Walter Lewin from a Bangladeshi physics lover.
Was Dave a student, He's really smart.
And also do MIT profs have dinner with the students!
If that's the case, that's how the relation between a student and a teacher should be.
All your students around the world love you.
David Pooley was my graduate student in 1999 when I gave these lectures. He is now a Professor in the US. He is very bright and also an outstanding teacher. He got a teaching award at MIT.
Incredible I don't have words to tell how amazing it is
Love & respect for you, Prof. Walter Lewin from a Indonesian physics lover
i have never enjoyed a lecture this much before thank you very much sir
If I was at these lectures I would never had blinked my eye..
Love your lectures.. ❤️❤️
I like the cameraman.....he always shows us some funny stuff 🤣
I always end his lectures with a smile on my face
Thank you for your kindness and generosity for the other side of MIT. We are blessed to have you sir. While I am desperate to this type of lectures.
My pleasure
Just got a 95 on my first college physics using Calculus exam! Wouldn’t be possible without these lectures
Amazing lectures, want me to study physics for JEE again , even after 18 years! God bless revered professor.
No offense ! I too love his lectures but at 9:42 " string has negligible ass" and then instantly says mass , massless 😂🤣.
😂😂😂😂😂😂😂😂🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣
🤦🤦🤦🤦🤦😝😝😝
U r a good listener
Sir for sure I think physics is taught in a really bad way but now I am sure in future I will try to be a proffessor like you
I am loving your lectures and these are so beautifully arranged that the concept becomes crystal clear
Really I am in ❤️ with physics now
Sir u r my role model . Ur lectures truly motivates me to work on physics
Dear Professor, I love the way you teach, especially those experiments. I wish to be your student. Thanks a lot :)
i have not clicked on this video to learn physics but to enjoy it like an entertainment, power of true physics
i will always wish to sit in your class to love the physics....Great sir
Teacher always made us start with Sum=ma (newton II). This is the most important line ever in any such problem!
Lec just goes on another level
Wat een verschil van lesgeven met mijn lesgevers 50 jaar terug in België.
Ik hou van uw stijl en humor en engagement.
Je geeft geen les fysica, je bent het!
I am in class 11 preparing for NEET. Your videos helped not only me but also many aspirants. Thank you very much sir .. 👃👃👃 (from India)..
you are the best teacher sir ...really a lot respect for you ..thank u sooo much sir
professor u are our newton of this century
You are my inspiration to learning physics I love your lecture...
You are best professor Lewin (W.L)
Sir I really want to meet you in my life....😭😭
I love watching your lectures, it makes me so interested in physics
+TheGiantOne good
Excellent lecture & demos!
45:16 - a couple of suggest for improvement...
There is a disconnect in terminology. The slide is actually accurate when it states "2g" & "0g". It needs to be understood that pilot language is being used here, like when it is said that an F-16 is pulling 9g's. Here "g" is referring to total acceleration, meaning the acceleration due to gravity _plus_ aerodynamic acceleration forces. The acceleration scale that pilots use sets "1g" equal to the acceleration due to gravity at the Earth's surface, so that's why they use the letter "g". The disconnect in terminology here is because the same letter is being used by different people to mean different things. Prof uses it to mean accel due to gravity, whereas the slide uses it as a scale for the measured total acceleration.
Another statement that needs to be addressed from that same point in the video:
"The engine is restarted."
I expect everyone is clear that the engines were never _stopped_ at any point during the flight. So what is really meant by "restarted" is that the thrust level is increased. During the parabola, the engine thrust level is set to only counteract aerodynamic drag. The net result of this engine thrust is such that the flight path and velocity would be as close as possible to the trajectory if it were to have happened if there was no atmosphere at all, like a spaceship would experience.
During the 2g pullout, a lot more thrust is needed, so the throttles are pushed up at that point.
In the big picture, my points of feedback here are minor. Overall this lecture is amazing! And it would be great if NASA were to be so clear and precise in explaining what weightlessness is and what it isn't.
Sir Your teaching style is amazing.I am now fan of you.thanks to youtube and thanks to you sir to give us these opportunity.Thanks a lot sir.This is my first public comment.please reply sir.I shall be greatful.
:)
Excellent lecture of Physics. Thanks to great Physicst of world. 🙏🙏🙏
It's my pleasure
love the sound the way you explain the motion of M1 and M2
🥰🥰
Listening to your lectures on physics helps
dude dude prof dave is amazing give him some appreciation guys its not easy to build that thing
Sir at 41:26, I think that the 45 degrees is for maximum horizontal range of the projectile because the range is given by u^2sin2(theta)/g
Yes
Why do you even want Maximum Horizontal Range?
We want Maximum time of flight!
I love his phrase "physics works"
i don't know how to thank you for these incredible and interesting videos!!!
Amazing explanation. Thank You doctor Lewin.
Love from India ❤️
🙏🏾🙏🏾 koi indian to mila great
Professor, I had a question. If you would answer this, I will be very grateful.The question is:
An object is in free fall when the force acting on it is exclusively gravitational. But why then the moon is in free fall? Isn't there centrifugal force acting on it?
I will be very grateful to you to know the answer. You have given me new eyes of physics to see the world. You've really made me love physics.
Thanks professor.
Lots of love.
Earth is in free fall - grav attraction of the sun is the centripetal force to keep the Earth in orbit. Moon is in freefall grav attraction of the Erath is the centripetal force to keep the Moon in orbit.
@@lecturesbywalterlewin.they9259 But does the centrifugal force act on the moon? If yes, how can we say that it's in free fall? I will be highly obliged if you'll clear my doubts on the topic. Thanks.
if only gravitational froces act on an object it is in free fall. That's the defintiion of free fall. The only forces on the ISS are gravitational forces; this the ISS is in free fall. If you jump off the table the only force that acts on you is gravity thus you are in free fall.
@@arctic215 The centrifugal pseudoforce is a fictitious force, as a consequence of solving the problem in an accelerating reference frame. This is why it is a pseudoforce, rather than a real force. If you use an inertial reference frame to examine the forces acting upon the moon in orbit around the Earth, there is no centrifugral pseudoforce term.
The moon is in free fall around the Earth, because no real force other than gravity acts upon it to make it orbit.
You are the physics teacher I wish I had in high school...
Great teacher........ I loved his lecture. Thank you sir.
You are welcome
Great prof. I can't help *but* point out the amazing slip just after 9:40.
what's the slip? I did not noice any slip
+Lectures by Walter Lewin. They will make you ♥ Physics.
Benjamin probably means the fact that you accidentally said "small ass". :D
Fantastic lesson. A must watch all physics students.
Sir, I have doubt on how the tension varies in different points of a rope??
If the rope is considered massless and all pulleys are considered frictionless, then the tension is uniform throughout the rope. The pulley simply reverses the direction of the tension.
Take 2 different points on a rope and say tensions at those points are T1 and T2 respectively.
Let the mass of rope between them be assumed to be "m".
For accelerating rope along T1. We have,
T1-T2=ma,
But for a massless string m is considered as 0. Implies T1 must be equal to T2.
Edit: Thus a constant tension T=T1=T2... on every point on string.
I love physics but sir when you learn physics my intereste is double triple increase.So thank you so much prophesier (WL).😊😊
Most welcome 😊
Happy birthday Master ❤️🙏
you are the one and unique,best wishes for you
i am just thinking .
when it was recorded
just curious. He is looking young .
But alas one day everyone have to go.
btw love u sir ,i hope u live long.
recorded in 1999
@@lecturesbywalterlewin.they9259 Well, the see-saw look alike for Tension example when both are equal..
Also
Now Superman in weightlessness can get extreme sickness.
Your demonstrations rock !! I wish we had such tools at school !
This is MIT, prestigious, well-funded, cream of the intelligence, etc
I think I am doing something wrong in calculating the time for an airplane to reach it's peak at 42:56
Instead of getting 15 seconds, I am getting 30 seconds
Here is what I am doing : ( Considering the motion in y direction only )
The V , final velocity in y direction is zero at it's peak so V = 0 m/s , u = 300 m /s , a=-g = -10 m/s^2
To calculate t , I will put the above values in equation V= u+ at ; 0= 300+(-10*t) ; -300 = -10*t ; 30= t
Where am I wrong ?
Yes, of course, if you get a different value from me, you did something wrong.
I forgot to convert the velocity into m/s from miles per hour :(
Sir , Awesome Lecture though ..couldn't have understood weightlessness before but things are making much more sense now 😌
:)
"6 times less"? My physics prof would have skewered me if I said "times less". He almost broke 2 of my fingers for arguing with him in class. Great guy.
I enjoy everything about physics especially the simple algebra at 15:00 that is used. I got lost though how was the a for acceleration isolated to provide the new equation of a=msub2-msub1/msub1+msub2 g?
Great lecture! Explained in detail the concept of weight! Also, amazing demos!
+Christos Stefanou Thank you
Brilliant demonstrations! Thank you so much!!
Glad it was helpful!
Thank you Sir. Your lectures really made me understand Physics better for my JEE Advanced Exam. And a doubt, is the motion sickness caused while traveling through waters also because of the change in weight due to buoyancy??
No. Buoyancy supports the boat, but the motion sickness is independent of what its cause the motion. Your weight does not change due to buoyancy, but due to the up and down motion of the boat.
Fantastic lecture. However, when it comes to the parabolic airplane problem beginning at 41:20 I am unsure how you calculated that the airplane would reach its sommet in 15 seconds since it has a speed of 300m/s and the only force acting against it is gravitational acceleration at 10m/s^2 which brings the sommet to 30 seconds rather than 15. Again, awesome lecture.
simple physics, watch the lecture again
A Question. 30:18 so when a plane is landing then the passengers weight should be gained tremendously. Shouldn't this cause a problem due to increase in weight??
only the vertical acceleration changes your weight. That's insignificant when a plane is landing.
Pilots try to approach the landing runway at a very gradual descent, such that vertical accelerations are reduced as much as practical, so that the landing gear is capable of supporting the touch-down forces. The aircraft engineers who designed the landing gear know about this issue, and have accounted for the increase in apparent weight when the plane touches down.
This is also why pilots have to dump fuel, when necessary to make an emergency landing. The mass of an airplane at takeoff is significantly greater than the landing mass, after accounting for the expected amount of fuel to be burned if the plane makes it all the way to the destination. When they have to make an emergency landing after only having burned a small fraction of their fuel, the plane will weigh more than the landing gear can withstand. The pilot has to release unburned fuel in mid-air, in order to make the unplanned landing safely.
Very nice lecture on weight chalks are incredible
In Jr high school my science teacher made "runner up" in the "teacher in space" program. We viewed this type of video several times. We viewed the space shuttle Challenger destroyed. I commented on it's explosion, and received a severe reprimand for it, followed by a sincere apology later on. His hands were shaking for a couple of days, as he was realizing it would have been himself... It's true...
at 15:17 is m m1 or m2 in the equation T=2mg/(m1+m2) ?
I substituted a in equation 1 and got
T=(2m_1 * m_2 * g) / (m_1+m_2)
can some one tell me what I did wrong?
Edit: never mind the professor corrected it
How did he derive the equation T = 2m1m2g/(m1+m2)? I substituted acceleration into the earlier equations and that's not what I got at all. I imagine I am missing some simple algebra but I get stuck no matter which way I go about it.
by solving this equation for T:
(m2g-T)/m2 = (T-m1g)/m1
What he meant when he said "If the system is not being accelerated" at 0:50 ?
Thanks , for replying my quest . Now these terms are quite clear to me
fact of all lectures ,At 13:05 the student is shown in this video, is always seen in about all lectures !!
Hello sir can u just explain that how tension on the left is equal to tension (Right) 10:47 minutes in ur video I can't visualise it properly
I explain that in my lectures!!
How is he able to make that dotted line at min 43:54? Also, why is he wearing a doughnut?
Best way to teach. Thanks professor!
Please can someone tell me why in 37:37 its 0
Isnt it just the force of gravity acting on the scale
What am I missing
The scale cannot measure true gravity. It can only measure the constraint force it applies to its pan and the load. When it is free falling, there is zero constraint force between its components, and thus it measures zero.
Sir i am not getting the homework question in description by clicking on link
ua-cam.com/video/TQR6VkYzAeY/v-deo.html