8.01x - Module 03.01 - What is a vector, what is a scalar.

What is a vector, what is a scalar.

[@kirankumarbalusu4517]

By watching this, I realized now that all my childhood is Bluff. Once a Master mind said, If you don't love your physics it's not your fault it's upon Lectures. Love you walter

[@Olympus.-oi4dm]

The master was Alakh Pandey

[@mecooper1755]

I love how he teaches, I 've learned so much, he is addicting..love physics!

[@lecturesbywalterlewin.they9259]

:)

[@tarunsinghshekhawat8692]

@@lecturesbywalterlewin.they9259 in india we have the physics teacher similar to you sir his name is H.C verma Author of book concept of physics.

[@dope_axel9436]

To be honest I hate physics but his lectures are great

[@veerannashetty2003]

I am an Indian sir ..... Everybody praises ur teachings.... But no one are asking how are u now..... How are u sir??... Are u fine??... TOday is GURUPURNIMA DAY IN India... Where we Indians thank all our teachers for imparting kniwledge U are my teacher... Thank you sir... May God let u live 100+years...

[@janardhansr113]

We need teachers like you in India so that we don't hate physics and start loving it

[@blackbeard5806]

This dude is the reason I am getting a doctorate in physics. Thank you so much

[@smeggle100]

Professor Lewin, thank you for sharing your knowledge and passion for it to the world

[@rahulrkarekar]

Thank you so much Mr.Walter... I gained a lot from your video... I am very fond of physics.... pls keep updating such videos more O:)

[@Sabrinathefishinggirl]

omg. i should have started here. Thank You. I have a better understanding now.

[@kaminiswain1371]

Very nice explanation.. Thanks a lot sir.. It's really making more passionate to learn physics after watching your videos... Such a brilliant legend on physics I have ever found on KZbin..

[@noname-wk3nl]

sir i believe that u are an essential part of physics.....for any student in the world physics is incomplete without u sir .... thankyouu soo much for everything ✨

[@tamsonmog5941]

Started watching ur lectures for JEE & NEET❤🌟 I will make it sir💪🏻 Blessings from you🙏🏻🙇🏻😇

[@pallavmahato7865]

Me too.

[@sugavaneshb6028]

Me 5😁

[@strangestranger4691]

Meeee 6.....😜

[@abhinavverma5859]

Are his lectures good for jee!

[@dking3563]

Why don't you watch his lecture for knowledge instead...

[@umeshyadav7625]

Thanku sir u r always our best heroes and ideal...

[@nurulamin-wv8ce]

What a great teacher.

[@whatthelove6386]

you are the best sir..wish I had this video in my schools

[@dearjuliet4230]

It's very fortunate that I am taking lectures from a legend. Future will see Walter Lewin sir as The Einstein of 21st Century.

[@nitinranacluster1737]

Walter sir you are great .I am theoretical physicist but I saw always your lecture.

[@lecturesbywalterlewin.they9259]

:)

[@vishwaujjwalupadhyay3102]

Love from India,sir.

[@jacobhenley8326]

I wish had this guy as my lecturer for mechanics at university.

[@iShowHackSpeed]

Love from India sir! 💜

[@chaitanyadeshmukh8341]

What a amazing teacher

[@universallappen1033]

I already ❤ Physics so those lecures make me ❤^2 Physics. (Or they make me ❤ you ?!) Greate work, very helpful for exams.

[@lecturesbywalterlewin.they9259]

:)

[@AbhishekSharma-od7vj]

I'm pursuing my Masters Of science in Biostatistics and I have always been interested in physics in my high school days, I really liked the subject, I would seat for hours solving sums and pondering concepts, I feel pity on those people who study science to get Job's and earn money, yes it is important but Science is the freedom that money cannot buy, its your imagination free of worldly chains.

[@numapompilius6364]

Cool!

[@RiyaKumari-di8id]

Love from India🤗

[@Yash-oo4nh]

Grrrreeeeeaaaaattttttt... 🚀

[@anushka_nd]

What I didn't understand for a whole year, I understood in 8 minutes today.

[@lecturesbywalterlewin.they9259]

:)

[@aironagroup2893]

I am engineer and had studied in a reputed college long back. But, sadly, it took me about 15 days back then to understand (courtesy, the teacher) what you have so lucidly and graphically explained in just say 8 mins. Great technique of teaching. Wish all teachers were like you...then India could have churned out better engineers.

[@lecturesbywalterlewin.they9259]

Glad I could help!

[@anshumanyadav7553]

@@lecturesbywalterlewin.they9259 Is current scalar or vector

[@saintpuff]

@@anshumanyadav7553 scalar

[@kamaldwivedi2456]

Best lecture on vectors.....Love from INDIA

[@new-knowledge8040]

By using the stacking of both Motion Vectors and Length Scalars to analyze the basics of motion itself, you can in mere minutes discover SR and also derive all of the SR mathematical equations, including the Lorentz Transformation equations. No prior physics education is required to be able to achieve this fantastic outcome.

[@lecturesbywalterlewin.they9259]

There are 2 postulates in SR. They cannot be derived. But they can be (and have been) tested experimentally.

[@new-knowledge8040]

My parents pulled me out of school ( Long story. In short, teachers thought of me as being a useless backward hopeless case. ). As a consequence of having left school, I had only acquired bare bone skills via the educational system. Having merely a foggy recollection of things such as the Pythagorean theorem and vectors, calculus and trigonometry have continued to remain an overall mystery to me. However, this had forced me to be performing only a very simple analysis of "motion" during the time in which I was fascinated by what motion actually was. This very simple step by step analysis of motion eventually led me to discovering SR. I have noticed however, that the manner in which I derived the SR equations does not seem to have been used by anyone else up to this date. Sadly, originality is usually mocked these days. If you ever have time to spare, an opinion of my "KSP Special Relativity" KZbin videos is always welcome.

[@lecturesbywalterlewin.they9259]

You should submit a paper to a refereed journal. There is NO doubt in my mind that if your math and physics is sound, they will publish it. The problem is that *SR cannot be derived* as there are 2 underlying postulates and postulates cannot be derived. But good luck anyhow!

[@johnrubensaragi4125]

0:18 Mass is scalar, weight is vector because it's a force.

[@rafatyusufi6711]

intresting I like it

[@creativelife9988]

Love you sir 🙏😌💐

[@applemansunlight8455]

This is some professor.

[@Leylayeesshh]

You are as my physics teacher as intersting and positive man. Good Luck 👍🏻 I learning so lesson. Thank you.👌 But I want to contact with you :)

[@RashmiRsahoo]

Sir how you are drawing dotted lines?

[@shahadatbashar4509]

You're excellent. Made me clear to understand the topic but i have some problems till now. Can you clear the difference between Gradient, Divergence and Curl. I mean they all are the multiplication of vector operator (Del or Nabla)..So how they could be different. And what they actually means and what is their uses in Physics. It will be very good for me if you help me to clear those.

[@lecturesbywalterlewin.they9259]

Gradient, Divergence and Curl. Use Google!

[@Boymania2004]

Keep up the good work, I wouldnt be able to pass my physics class (almost identical to 8.01) in college without the help of Walter Lewin and his online lectures, Im in EE, now starting with electromagnetism and such, which seems to be connected with physics

[@lecturesbywalterlewin.they9259]

+Boymania2004 EXCELLENT!

[@harshalshinde227]

how does someone arrive at that formula of the magnitude of vector A ? Please explain, is that pythagoras theorem or something else. I am new to this vector thing. I find vector absolutely intimidating , so kindly tell me more resources where I can grasp the concept of the vector

[@elishasmile]

Helloo sir, are there any Assignment questions available for 8.01x (Vectors)

[@AyanKhan-jg1yz]

Sir i like your lectute very much Its my dream to meet you sir😄😄

[@lecturesbywalterlewin.they9259]

Come to Cambridge, MA USA and we can meet.

[@ilsimi3599]

It should not be a question of preference, everywhere notations have to be the same.

[@hrishikeshdube]

Sir plz start a couse for jee mains and advanced !!!! Plz sir 🙏🙏

[@manashbhatta9253]

sir, is current a vector because in my classbooks it is called a scalar but in books like electrodynamics by griffith it is called a vector

[@lecturesbywalterlewin.they9259]

use google

[@vishwaujjwalupadhyay3102]

❤️ physics 🙏

[@MsSujoy]

Why cross & dot product of two vectors are defined like ABsin¢ and ABcos¢ respectively?

[@lecturesbywalterlewin.they9259]

There is a NEED in math and physics for cross and dot products.

[@vasundharapitchuka1976]

It's my first lecture sir and the lecture is super amazing. Hope you are healthy and safe... #love from India

[@rahulrkarekar]

hello Mr.Walter, I had a doubt in mind. Please clarify me. How can Time be a scalar quantity? Since time has both Magnitude & Direction... Time Travels From Past / Current to Future...

[@lecturesbywalterlewin.they9259]

Rahul Karekar Lectures by Walter Lewin. They will make you ♥ Physics. 1 day ago Rahul, read this website @59782 "The confusion arises because you have to define carefully what you mean by the word time. In special relativity we label spacetime points by their co-ordinates (t,x,y,z), where t is the time co-ordinate. The numbers t, x, etc are not themselves vectors because they just label positions in spacetime. So in this sense the time co-ordinate, t, is not a vector any more than the spatial co-ordinates are."

[@lecturesbywalterlewin.they9259]

Rahul Karekar Lectures by Walter Lewin. They will make you ♥ Physics. 1 day ago Rahul, read this also in.answers.yahoo.com/question/index?qid=20080830205352AAlA6pk Suppose time is a vector quantity.Then it should obey vector law of addition.As you say it has only one direction,The resultant will always be an algebraic addition of the individual times.So by this property it is a scalar. As a vector needs the direction to be specified for its complete information.But as time is always going forward,there is no need to mention its direction.Hence time fails to satisfy one of the basic properties of a vector.

[@lecturesbywalterlewin.they9259]

Lectures by Walter Lewin. They will make you ♥ Physics. Lectures by Walter Lewin. They will make you ♥ Physics. 3 days ago Rahul, read this website @59782 "The confusion arises because you have to define carefully what you mean by the word time. In special relativity we label spacetime points by their co-ordinates (t,x,y,z), where t is the time co-ordinate. The numbers t, x, etc are not themselves vectors because they just label positions in spacetime. So in this sense the time co-ordinate, t, is not a vector any more than the spatial co-ordinates are."

[@rahulrkarekar]

Lectures by Walter Lewin. They will make you ♥ Physics. Yeah! i think i got it Mr.Walter, thanks for the explanation. Maybe what you are trying to suggest is that, when we define time, it is just the current or fixed magnitude of the required space-time, it ain't travelling anywhere... Am I correct? --- Rahul Karekar

[@rahulrkarekar]

Lectures by Walter Lewin. They will make you ♥ Physics. yeah, totally agree on that, since it is a given that time travels only in one direction, the Direction aspect of it is not considered & also that it dosen't satisfy the vector law of addition... Got you. thanks again --- Rahul Karekar

[@shikhrrr6275]

Just one question (maybe I'm stupid) In beginning sir said that "your weight is scalar". I'm just a high-school student and from my grade 9 knowledge I remember that weight is a force, and forces are depended on direction. Then how can weight be vector, I mean, you cannot measure your weight by putting the weighing machine on your head! Plz if anyone notices that *I am* wrong or confused, then please help😃😃

[@balino6734]

Sir wants to say about mass that it is scalar but may be to make it more clear he said weight You are right weight is a vector as it is a force

[@oristonellc7307]

Sir, is scalar product of any two vectors is always scalar?

[@lecturesbywalterlewin.they9259]

yes

[@user-tm1ix7xi1n]

oristone llc whenever you take a dot product of two vectors it will be a scalar

[@ferchavalos4681]

Great explanation!

[@shivag-lb8ws]

Why breaks vector in components??🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔🤔

[@hariompatel7741]

I am in 11th grade thanks for this

[@himanshukumar8881]

Good evening professor, professor I have a question that is why we need two types of vector multiplication.

[@lecturesbywalterlewin.they9259]

watch my 8.01 lectures then you will understand

[@himanshukumar8881]

@@lecturesbywalterlewin.they9259 thank you so much professor

[@Marshall...-_-1101]

Sir roof is as cap(asking)

[@AlexandruVatamanu]

00:30, i thought temperature is a scalar only if say you answer "20" when asked "how cold is it?" but if you said "20 degrees" then 20 is the scalar and degrees is the vector because it carries the scalar. vectors described in terms of magnitude and direction requires the definition of magnitude and direction. vectors described in terms of tuples of scalars require the retrofit of coordinates system back to vector world. the reason vectors bring 80% in high school is that they are taught by teachers unable to teach but very able to mark down the tiniest imperfections in student understanding of the concepts. valid throughout the education process. anyone starting vectors with magnitude and direction is not worth the time.

[@lecturesbywalterlewin.they9259]

>>>but if you said "20 degrees" then 20 is the scalar and degrees is the vector because it carries the scalar.>>> incorrect

[@vinaykumardaivajna7276]

Sir please tell me about the GRADIENT of a scalar becomes a vector

[@lecturesbywalterlewin.they9259]

use google

[@TEAM-RC7]

PLEASE I WANT QUAMTUM PHYSICS FROM YOU SIR YOUR TEACHING IS MAKHAAN

[@elena6519]

I just wanted to thank you for renewing my love of physics. My recent teacher is frankly not the most motivated, but your electricity lectures really helped me out. By the way, I also use these lectures to learn English (I'm a German student), allowing me to kill two birds with one stone. So thanks for that, too :)

[@lecturesbywalterlewin.they9259]

:)

[@WhoAmI-do3vy]

❤

[@xyz8282]

Sir I want to study from you in MIT classroom :)

[@konidinasandeepkumar6814]

Sir.. how is it different from a tensor?

[@lecturesbywalterlewin.they9259]

google "tensor"

[@avantikagupta3344]

Why there is no ad in any of his videos??

[@lecturesbywalterlewin.they9259]

I see ads

[@avantikagupta3344]

@@lecturesbywalterlewin.they9259 Sir, I am still not believing that you have replied to me sir I am a big fan of you I love your lectures a lot I see every lecture of MIT hence I am only 16 years but I try to understand everything which you teach!! And I am Indian

[@krishvora2026]

sir, how do you project a vector onto xy plane?

[@lecturesbywalterlewin.they9259]

ask google

[@user-tm1ix7xi1n]

Krish Vora whenever you project in xy-plane doesn't Z becomes 0? Or what if we use projection formula for it? I am not very sure but i think these cases might work

[@lecturesbywalterlewin.they9259]

comment and question are unclear

[@carultch]

​@@user-tm1ix7xi1n Given a 3-dimensional vector, making the z-term zero will generate the projection onto the x-y plane. Given vector V, the projection of V on the xy plane (Vxy) can be calculated as the following: Vxy = (V dot x_hat) * x_hat + (V dot y_hat) * y_hat + 0*z_hat. The z_hat term is zero by definition, because we want a vector that is in-plane with x and y. The x and y terms are dot products of the vector with their respective unit vectors.

[@lecturesbywalterlewin.they9259]

@@carultch hello Carl. I have contacted my post office. They have a way to check where and when your package has been scanned last. It's Aug 13 in Springfield, MA. Clearly, your book is probably stuck there somehow. My post office will contact Springfield in the hope that my package to you will be found. best, \\/\//////@lter

[@puri5434]

😊

[@roohulamin3831]

Sir kindly explain why vector division is not possible

[@lecturesbywalterlewin.they9259]

use google

[@kalyanimohanty8206]

​@@lecturesbywalterlewin.they9259😂 perfectly roasted

[@unusualthinking1581]

sir,how weight is a scalar?

[@lecturesbywalterlewin.they9259]

Weight is a force which is a vector and has a magnitude and direction. Mass is a scalar. Weight and mass are related to one another, but they are not the same quantity.`

[@unusualthinking1581]

+Lectures by Walter Lewin. They will make you ♥ Physics. ,thanks,I was confused before you answered to my comment.

[@anshumanyadav7553]

Is current scalar or vector

[@lecturesbywalterlewin.they9259]

Current is a scalar value despite having magnitude and direction. It reflects the positive charge flow direction, but it is considered a scalar quantity *since it currently uses scalar addition laws rather than vector addition laws.*

[@anshumanyadav7553]

If there is two body in which one body is at rest while other body is in motion then there is any variations in mass or not

[@lecturesbywalterlewin.they9259]

@@anshumanyadav7553 E=m*gamma*c^2 gamma depends on the speed, m does not

[@anshumanyadav7553]

@@lecturesbywalterlewin.they9259 Are you walter lewin

[@arjundan007]

Wait a moment weight is not a scalar it is a type of force so it should be a vector as force

[@ibrahimtemiza4322]

I Want to put vidéos explained mécanique of a matériel point

[@bmg2256]

Scaler is the easiest lesson I've ever had

[@meikejune4009]

A mother has thousands of vectors.

[@sudju99utube]

@ 0:21: "your /weight/" scalar?!

[@lecturesbywalterlewin.they9259]

what is your question?

[@sudju99utube]

Sir, in this clip @ 0.21s, you cited ( though in very general & casual sense) " weight" as an example of scalar...though it's a vector quanity being a force...my question is whether it was by mistake that you told so that time? ..Big fan of your's from India..Please accept my profound gratitude for making me love physics..

[@lecturesbywalterlewin.they9259]

I should have said "mass is a scalar". Sorry

[@sudju99utube]

Sir.."humility" is the attribute that goes with all greats like you... not only you teach, you inspires..and please forgive me if by any means you are hurt by the observation made...warm regards..

[@lecturesbywalterlewin.they9259]

not hurt at all; on the contrary. Watch this lecture; it's all about weight and mass. kzbin.info/www/bejne/kGGapYerepagrc0

[@rollno1aaradhyakumar138]

Sir are you on Instagram

[@rickydash6709]

sir you said weight is a scalar but it has also a direction.

[@lecturesbywalterlewin.they9259]

mass is a scalar, weight is a force it's a vector.

[@daksharyavanshu7964]

:)

[@shashanksingh9398]

I did 1k like😅

[@shwetasharma154]

His lectures are mind blowing....sry mind boring.... Its just too basic and old...not jee main or even neet level...

[@lecturesbywalterlewin.they9259]

Keep in mind that MIT is only a very mediocre University. That's why only 100 people who studied at MIT or who lectured there received a Nobel Prize. *That's very embarrassing.* Luckily you got a much better education.