Cross product 2 | Magnetic forces, magnetic fields, and Faraday's law | Physics | Khan Academy

Courses on Khan Academy are always 100% free. Start practicing-and saving your progress-now: www.khanacadem...
A little more intuition on the cross product. Created by Sal Khan.
Watch the next lesson: www.khanacadem...
Missed the previous lesson? www.khanacadem...
Physics on Khan Academy: Physics is the study of the basic principles that govern the physical world around us. We'll start by looking at motion itself. Then, we'll learn about forces, momentum, energy, and other concepts in lots of different physical situations. To get the most out of physics, you'll need a solid understanding of algebra and a basic understanding of trigonometry.
About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.
For free. For everyone. Forever. #YouCanLearnAnything
Subscribe to Khan Academy’s Physics channel: / channel
Subscribe to Khan Academy: www.youtube.co...

[@billcheung163]

the most impressive things about these videos is his right hand rule drawings....gives a nice visual...thanks.

[@Novecento]

This video is priceless!!! I've struggled for hours with my copy of "3D Math Primer" book trying to understand what cross product is really about and then I've found your video and BOOM! I've got it! Thank you so much for your help!

[@chelseaallan7]

"If we were metal filings living in a strong magnetic field we'd probably have a better intuition of this" lol!

[@rebaz1337]

you're instantly and permanently my favorite person.

[@rodoshi963]

Is he still your favourite person ?

[@ggmm117]

Sal sums its up at the end like a BOSS. "You use your right hand, point in like gun, make all your fingers perpendicular and then you'll know what direction that vector points in."

[@wetim99]

another method is moving your index finger from the first vector to the second. if your index finger moves to the left, it is coming out of the screen, like a screw, if it moves to the right, it is going into the screen. righty tighty, lefty loosey. i believe it is called the screwdriver rule.

[@masterprofession]

Wahhh!!! U truly deserve appreciation for your efforts and hard work.

[@Nuhahossainy]

Thank you.. For the first time I understand what vector cross means

[@vinnv226]

Thats right, "axb" and "bxa" are along the same line, they're just in exactly opposite directions. Imagine drawing the vectors a and b on the ground, and then sticking a pole in the ground where they meet. axb would be the vector along that pole pointing towards the center of the earth, while bxa would be the vector along the pole pointing towards the sky.

[@MattOGormanSmith]

It's a convention. Elsewhere, when using hands to distinguish cartesian co-ordinate systems, X is the thumb, Y is the first finger and Z is the middle finger.

[@anishaghosh101]

U r an artist with science I HV ever seen

[@Barnekkid]

I've encountered this before in Calc III but it was NEVER THIS CLEAR.

[@Ren520]

ur right =p im taking calc 3 and general physics, and both of them will teach dot/cross product in the beginning. so i dont have that prob, but i guess most engineering students will learn dot/cross in physics first

[@Arzenimus]

Hahaha moments like 2:08 make me not stop loving you! By far the best tutorials on internet!

[@bacakomen6019]

Tq khan,may God bless u

[@terencewright2223]

Excellent video. Thank you.

[@josephguse]

This is good, but when you are trying to build intuition, you could just say that the magnitude of the cross product is equal to the area of the parallelogram implied by vectors 'a' and 'b'.

[@dorcasekene3898]

I got exactly what i wanted. thanks

[@vector8310]

"Your index gets the first term, the middle finger gets the second term". Finally I get it. THANK YOU!

[@fezo1]

Yeah, I agree 3D Math primer seems to glaze over dot and cross products.

[@June28July]

Never thought I'd find gang signs in a math tutorial! :D BTW, my book describes the RRR differently. You base the orientation of the cross product on the direction the fingers curl... Confusing as heck...

[@abhikamune83]

thank you very much... its a great help...

[@hafidzaziz7508]

very helpful..hatur nuhun

[@Opticx25]

aweasome video really helped a lot

[@Paulorific]

I find the alternative right hand rule way easier to actually do. You can find a video on youtube describing.

[@orchoose]

can u imagine how frustrating this must be for right hand amputees they have to do inverse right hand rule on left hand

[@brod515]

It wouldn't be that hard though... i think they would just have do the left hand rule and know the answer will be the opposite direction

[@kangaroosinantarcticayes9220]

In Ukraine there is a left hand rule, which i find much easier actually. At least, because you can write and perform the rule at the same time. And, in my opinion it`s easier to understand and do (the a is the pointing finger and b goes into your palm).

[@qwobify]

'a x b' and 'b x a' are both cross products which are perpendicular to a and b respectively. does this mean that, if you have two vectors (a and b) there is more than one vector that is perpendicular to both a and b? ('a x b' and 'b x a'?) how is this so?

[@Tyrant_13]

They didn't choose the right hand out of convention--they chose the right hand because they found, experimentally, that that direction scheme displayed on the right hand comported with the physics data as opposed to the left hand. It wasn't because there are more right-handed people than left-handed people or something like that.

[@bhargavib707]

Here the right hand rule can be applied only if the two vectors are orthogonal .. but in this case it's 30deg does it makes no difference???

[@marcunator]

@thebutleress Because if you do so, you would get an opposit result.. Left hand rules are only used (as far as I know) for a Lorentz force.

[@lastshadowmonkeys]

You're brilliant!

[@tnzlr]

Great vid. Thank you. But what if the angle between a and b was something like 100 degrees, where there could be no right angle onto b?

[@fatimasalman790]

It is repeatedly being said that you have to consider the smaller angle. When you r saying the angle is 100 degrees, this means that you are placing the vectors incorrectly. So place them correctly and then the angle between the vectors will be 80 degrees and you can further solve the whole problem Hoping that u get it

[@rigel1167]

he is an artist.

[@Max11551]

It must be. At least, I've encountered it only in Lin Alg class this far.

[@ege1993]

This is really helpful thanks!

[@Rand0mAsian]

thank you khan, your videos are really helpful!! my lecture in university makes me sleep, but you dont ^^

[@fatimasalman790]

Same here

[@harishli2020]

awesome explanation.... :)

[@peanutbutter369]

Most fond childhood memory, playing with water lol.

[@qwobify]

wait i think i get it. both 'a x b' and 'b x a' are along the same 'line', if you will. it's just that their directions are opposite? using the right-hand rule and flipping it round it seems that way...

[@ChopsticksKilla]

thank you for making this

[@MrBlamazing]

nice video very helpful

[@Selenium188]

Tnk u very much

[@takemeway]

You are the best !!!!!!!!!!!!!!!!!!

[@amirk27]

a bundel of thankssssssssssssssssss khan we love u

[@sophiagnzjms]

Really nice art skills

[@LNasterio]

wait... so how do I calculate for cross product with 2 vectors again?

[@subarnasubedi7938]

Why does cross product give a vector which is perpendicular to a plane?

[@thebutleress]

why is Right Hand Rule used and not Left hand rule?

[@tysbaby6339]

Woah Kahn, maybe you've played with water..

[@brco2003]

Is this a linear algebra topic?

[@thebutleress]

@marcunator thanks :)

[@Lana_Sol3900]

Is it just me or does anybody else realize that Mr. Sal discussed Fleming's left hand rule but he called it the right hand rule???? BTW in my opinion this is too much math. xD

[@roseb2105]

confused... i just tortured my hands trying to understand this

[@0rangeflava]

how can vectors point of of a page when they are multiplied? I can't visualize this.

[@IllIlIIllIlIl]

Dont think of the cross product as multiplication

[@irfansyakir6916]

may GOD bless to who make this video...^_^

[@WhyPhi]

“Let me redraw it” .... what if we didn’t let him redraw it? 🤔

[@MrThepinkeagle]

Person status: Favourite.

[@gfot5758]

I dont get the right hand rule. My thumb stays the same xd. Can someone explain ?

[@Ebookish]

My thumb goes down both times, should I go to the Doctor?

[@chereoge]

You're not the only one. My thumb doesn't even change.