Introduction to torque | Moments, torque, and angular momentum | Physics | Khan Academy

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An introduction to torque. Created by Sal Khan.
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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.
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Опубликовано:

21 окт 2024

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Комментарии : 304

@benjaminriseman6855 2 года назад

I teach AP Physics and my students love your videos! I don't even assign textbook readings; your videos work much better as supplemental study material! Thank you Sal

@RM-en4uc Год назад

total agree!!!!!!!!!!!!!11

@khanacademy 16 лет назад

Yes. Distance is specified by a magnitude and direction.

@ksdnsdkumar1375 5 лет назад

This is the first comment for this video.

@leif1075 4 года назад

How do you k ow that torque force is transmitted equally across the whole bar...specifically why do you multiply that force by the total distance 10...you don't justify that step..How do you kbow the force doesn't weaken as distance from the point the force is applied increases..this is a valid and intelligent argument..

@Waeweas Год назад

@@leif1075 Well, it's baked into the formula. You can see that torque is proportional to distance. If you want proof for that formula then you'd need to run an experiment using a torque device with different moment arm lengths. There are tons of youtube videos showing this. If you want a written explanation for the reason the experiments verify the formula I can give you that as well: If you are rotating a body (applying a torque) you are doing work to rotate it over an angle. The same amount of work will be needed to cover that angle no matter what. At a greater distance from the axis the arc is larger, there is more distance to cover the same angle. So if the work required is the same but it is applied over a greater distance, you will need less force. The moment arm affects the force in a torque because a larger moment arm, radius, or perpendicular distance means more distance to cover the same angle of rotation.

@tanimnasiri 8 лет назад

Good basic explanation. Wish i could find videos that actually match the rigor of my physics class :/

@fasihussaini8554 6 лет назад

Class 11 physics does not match the rigor of University 1st year Calculus based physics which he is talking about as class 11 physics does not have a lot of calculus involving differential equations.

@LFCtushar 3 года назад

@@fasihussaini8554 hahaha 😆 when you don't know what torque means physically and you are studying physics and talking about calculas🤗

@cory99998 3 года назад

@@LFCtushar physics using calculus?? Blasphemy!

@pixelart0124 9 лет назад

Introduction to Torque gets over half a million views.. talk about an outstanding job!

@luongmaihunggia 6 лет назад

A million now.

@edmundgutierrez7491 6 лет назад

Pixel

@geniumme2502 5 лет назад

This video has more views then pixel at its max resolution :D

@pikmin4000 4 года назад

@Drik Sarkar you meant 1.3 million.

@lorikumollel3300 4 года назад

@@pikmin4000 you meant 1.4 million

@louiethemouseful 11 лет назад

Miley's favorite Physics topic.

@johnjohnh15 10 лет назад

Satoru Iwata Flop joke try again next time

@jordanheinemann6633 8 лет назад

Don't listen to the haters. I laughed.

@louiethemouseful 8 лет назад

Jordan Heinemann Thanks!

@khizras1006 5 лет назад

Hi ...after 5 years😂

@dingdong475 5 лет назад

What???

@shikirara 11 лет назад

These videos are amazingly helpful while studying! A good example to use in future would be a see-saw, and I suggest that small points you mutter to be made clearer, like all the torques equal 0, I had to re-watch the video to find that. But otherwise fantastic job thank you so much!!

@ennraii 13 лет назад

THANK U SO MUCH. I have a physics test coming up, this helped alot.

@jonashtimothy 14 лет назад

u help me in my difcal now ur helping me in my physics.. men ur very kind.. how can i pay ur gratitude..

@mellygirl23 11 лет назад

You're voice is so soothing at 12:30am :)

@nishantbahuguna5461 9 лет назад

your*

@NA-is2oo 7 лет назад

Your*

@armageddon.4488 7 лет назад

12:57 am, exam tomorrow :p

@rajveer3756 5 лет назад

Oh God

@anushagupta892 4 года назад

Woahh found the comment at exact 12 30...! Couldn’t agree more !

@VSPG_SIVANI 9 лет назад

As usual I love science, I love Sal. Outstanding explanation!

@amrelseweifi5640 9 лет назад

+Vln Murthy Yeah, physics is awesome, huh?

@jacobmoore788 5 месяцев назад

I am using your videos to supplement my MCAT studying. Thank you so much!!

@Synochra 10 лет назад

>Desperately look for videos explaining the topics of interest. >See Khan Academy video >smile on my face

@forkknifeo4429 7 лет назад

Synochra because you r dumb

@markyouneva7840 4 года назад

Me: getting up to leave Teacher: Why are you leaving? Me: Wrong class. I signed up for introduction to Twerk.

@goldenbells12 12 лет назад

thank you so much for this lesson. after 2 weeks of winter break, I had lost all knowledge of physics. this video at least partially restored what I had forgotten. please continue making these wonderful videos :)

@hashirscam 5 лет назад

Your comment is 7 years old? -feel old yet xD

@leungkonrad3215 2 года назад

@@hashirscam you too

@hashirscam 2 года назад

@@leungkonrad3215 Lmao 😭

@i2007t 9 лет назад

I like to visit you one day and thank you for everything I learned and learning from you.Hus.Australia

@jewbagel5969 4 года назад

rip Australia

@strangerbooy 9 лет назад

Your way of teaching is amazing, love it

@Jeffs5centk0 12 лет назад

It depends on what direction your going, Counterclockwise (cc) is positive and Clockwise(c) is negative, if you need something to remember this by, think of one c as a negative, (c = -) then (cc=+) because a double negative is a positive

@drevilpolo7 15 лет назад

I seriously think the colors help me from zoning out..it's like light bright on steroids....and they really help distinguish different concepts.

@musicaldarpan629 3 года назад

Hii after 11 years 😂😂😂😂 what are you doing nowadays

@drevilpolo7 3 года назад

@@musicaldarpan629 Currently on television and earning my Ph.D.

@perth7664 2 года назад

@@drevilpolo7 :D

@shoyohineta3573 11 месяцев назад

lol a 14 year old comment dem ... ig i was 2 back then

@shoulderescape 7 лет назад

You've taught me more than my construction teacher did in three 30 minute lectures

@Strive4VicTORI 12 лет назад

I love the colors! Thanks a lot. You should teach my college course.

@cradleblaze8798 4 года назад

OMG! It still holds true in 2020.

@nekuza-ut1bb 7 месяцев назад

Bruhh..

@keinsent 6 месяцев назад

😂math is timeless my guy

@kelvinkersey5058 4 года назад

so much clearer than all those videos of people shouting, joking and cramming as many words into a second as possible. But a script and a little prep would spare us the hesitations and the gibbering

@johnmandrake8829 7 лет назад

this was helpful thank you

@naseemamatheen9016 4 года назад

This is so helpful👍

@Frances3654 11 лет назад

i just ike how that word sounds.... torque, so cool!

@nivyaeswar6335 3 года назад

Thanks Sal, my physics teacher just confused me so much... 😀

@nvdp999 14 лет назад

@khanacademy No. Since Direction is not associated with the distance covered, it is a scalar. Displacement is a vector quantity.

@freezingbeast 14 лет назад

@saadnizamani i believe the joules is reserved for work, and Netwon meters is typically used to designate torque. The unites (while technically equal) are not often switched so you can distinguish torque vs work

@hlarios1991 12 лет назад

I wish my professor could teach like you cuz you put it in a easy way

@JiGsAwMoFo 15 лет назад

Yes, but if you noticed he states that work is fundamentally different than torque because for an object to do work the force must be parallel to the displacement. Whereas with torque, the force is perpendicular to the lever (moment) arm.

@grim107 14 лет назад

@khanacademy If you really want to get semantical, distance is a scalar and displacement is a vector. The distance between two points can change depending on the path one takes, whereas the displacement is unchanging. Distance is to displacement as speed is to velocity: Speed = distance / time Velocity = displacement / time At least that's the way I learned it...

@akashinojora4956 10 лет назад

Thanks you soooo much.....now i've understood why my uncle was able to open up the car tyre's screw with a longer pipe........ when i had been kicking so hard with a shorter one but still wouldn't open!!!!!!!!!!

@xvaltak 11 лет назад

Excellent video, thanks for the closed caption.

@audsubers 2 года назад

Im a junior in college studying biological engineering and these videos are awesome reminders

@imegatrone 12 лет назад

Steady I Really Like This Video Introduction to Torque

@cpgnition 15 лет назад

Very helpful. Thank you.

@johnsmith-qw2is 7 лет назад

those explanations were great though nice work sal

@ViktorVonGhoulie 12 лет назад

Khan you're a lifesaver!

@johntindell9591 7 лет назад

thank you very much

@rbkstudios2923 7 лет назад

It's not just about force and displacement being perpendicular to each other... it's the dot product

@adityatejaswi8750 7 лет назад

Thank you for the explanation !!

@gamingnavi 8 лет назад

Thank jegus for this channel. If this didn't exist, I would've failed my physics final.

@xyliahvortex661 3 года назад

jegus

@Biology_teacher2 2 года назад

Thank you

@Capreeca 13 лет назад

Determine the minimum force F that must be applied to the block of mass=50 kg such that the block of mass m=10 kg does not slide relative to the block of mass M. the coefficient of kinetic friction between all the surfaces is 0.2, and the coefficient of static friction between all surfaces is 0.3. The ramp in inclined at an angle of 30 degrees above the horizontal.

@fwesh1 13 лет назад

@khanacademy actually I believe distance is a scalar. Displacement is a vector.

@PurelyFizzycal 14 лет назад

@khanacademy Distance is a scalar quantity. Displacement is a vector, as you stated "distance vector" then it has a direction so your right in that way.

@knightwalker00ourgod2 7 лет назад

it helped a lot

@yohanah82 12 лет назад

Thank you for your videos.. it is very helpful on my review classes..

@smckix 11 лет назад

Think about the distance your hand his moving versus the distance moved by the center of the door. At the handle, your hand moves about twice as much as the door, but near the hinge, your hand hardly moves at all, but the door moves a lot.

@HappyProletariat 14 лет назад

You don't need to worry about clockwise and counter clockwise being positive or negative. The first force is being applied at a 90 degree angle, and the second force is being applied at a 270 degree angle, and since T=Frsinθ, we can see that the 90 degree force is positive (sin90=1) and the 270 degree force is negative (sin270=-1).

@ARMY28. 2 года назад

why it will rotate around center of mass, and not simply undergo translatory motion, when the rod isn't fixed at a point

@lucasolivares7245 7 лет назад

Physicist use the term "torque" while engineers refer to the term "moment." So instead of saying lever arm, they carried that aspect over creating "moment arm."

@dagrome 12 лет назад

Much better than the way my physics professor taught it.

@TheScienceCube 6 лет назад

Superb!

@EclipZeMuzik 6 лет назад

hell yeah bro!

@monchikichiki 14 лет назад

THANK YOUUU!

@Hassanworld786 4 года назад

Good explanation

@akxshn 6 лет назад

Love this video. Helped me a lot

@bathunter14 13 лет назад

@khanacademy Distance is a Scalar Quantity, as it only has magnitude where as it is displacement which is a vector quantity, having both magnitude and direction.

@LeoAugustom 12 лет назад

If your teacher can't, Khan can!!

@Faisal_Alra 10 лет назад

Great explanation Bro! Thank u

@ramsey180 12 лет назад

Khan you're my Hero

@piyumisugandhika6588 8 лет назад

great explaination :D thank you

@ifanf 11 лет назад

thanks!

@RachelWhitlock11 14 лет назад

Dude this was soooo helpful :D

@keeb_dev 13 лет назад

@khanacademy Distance is a scalar... Displacement is a vector.

@roxoroxoroxo 14 лет назад

my doubt is, what does torque really measure? I mean, in a practical way, what do we use it for. I don't mean in exercise solving, but actual day-to-day problems. by the way, thanks for all the videos, they've helped me a lot.

@21beal21 4 года назад

Work in a warehouse moving long 10 ft duct tubes and you'll apply these concepts every day. Its easier to lift and move the ducts from the center of mass. Even though they're lightweight overall, if you try to carry one from one end, it will seem crazy heavy. So when it comes to maneuvering them, this torque knowledge comes in handy

@LOLWAAHH 11 лет назад

"You know then that the net twerk is zero" That was literally what I personally heard

@rotflmaopmpqxyz 13 лет назад

On the last problem it wouldn't rotate but would it still accelerate upward because it has like a net force of 15 newtons on it?

@shreyasm3140 8 лет назад

Great explanation ! 😊😊😊😊😊😊😊

@amrutvani2 11 лет назад

If I view ur ruler from the other side ( from behind the wall ) counter clock rotation will look like clock wise rotation.So what is the correct direction of torque ?

@way0to0go 14 лет назад

thank you very much (:

@seanwalker2555 8 лет назад

woah i get itttttttttttt!!!!!!!!!!!!!

@pponcho8245 12 лет назад

thanks.

@CYLINDER-lk3il 10 лет назад

i love khan academy

@khajiit92 13 лет назад

work is in same direction as displacement, torque is perpendicular to direction of displacement. (from what i understand, i think sal is saying distance by mistake)

@ekam0671 7 лет назад

thxx bro u were helpful😆😆

@leoliu7492 6 лет назад

The equation of torque is tau=r x F, but the formula that you give me is tau=F x d, which is equal to the -(r x F).

@derekclark4133 9 лет назад

After about the 12th video of Khan Academy, I hope everyone realizes to put this guy on speed X 2. Settings-speed-2.

@luongmaihunggia 6 лет назад

2x speed is too fast to catch up with

@jeriemaihreyes5670 6 лет назад

lol i put mine on .75x speed

@musicaldarpan629 3 года назад

I am from future 😂😂😂2021 It's interesting to read 8-12 years old comments here 😅

@jnwmja 13 лет назад

@FireBallAX1 Well It's a start, and thank you very much. I'm not a physics student and I have no clue. Thanks for you're time.

@jnwmja 13 лет назад

Can you tell me how much torque i need to rotate 270lbs balanced with the distance vector exactly 1ft and i need it to move from point of force 8inches in 0.90seconds? Or do you already have a video to show me how to figure it out? 2,400vids is too much for me to search through. Thanks.

@abdelrahman4436 6 лет назад

please , I have been extremely keen to know , in the equation where: driving force*speed = power , when the speed is zero , like if an engine is going to move a car that is at rest , what exactly goes on , thanks

@chongjoseph3752 9 лет назад

Just a question: if the object is in a space shuttle, how does the mass at the centre act as a pivot? Or is it just a misconception?

@ThePhoenix042 9 лет назад

Since it has no other object to pivot around, it will pivot around its center of mass (which in the case of the ruler, as it has equal mass on both ends, its center of mass in the center of the ruler)

@aayushpotdar1592 4 года назад

@@ThePhoenix042 najs

@gensyed 4 года назад

Hey Sal, if I moved the object using a crowbar as leverage and move it a distance, would you call it torque or work? TQ.

@jaklapally 4 года назад

Good

@Cesariono 12 лет назад

I only did it because you said so. It feels so weird, like a "Phantom limb" effect.

@Roots7057 7 лет назад

thank you for your explanations.now i got one doubt that whenever while finding the torque why should we take the force which is perpendicular to the axis of rotation? is there any reason ? explain me if someone knows....

@GaneshKumarIIT 7 лет назад

Murughia Pandian this is because only the perpendicular component of force is useful for causing rotation . the turning effect of a force is because of its perpendicular component . you can see this experimentally , if you apply any force parallel to the rod there will be no rotation .

@Roots7057 7 лет назад

thank you GK for your kind reply..

@mfrekerara 14 лет назад

@khanacademy Isn't distance a scalar quantity and displacement is vector?

@ashokkrbishnoi 5 лет назад

concept in useful

@nnhhl6447 8 лет назад

if you push an object at a point other than centre of mass it will start rotating right? so what if im in space and someone pushes my legs and as I start rotating, i change my position thus my cm?

@anupamakeshri5572 8 лет назад

NNhhL Ur profile is oooooo cute I love pokemon & pokeshipping 😊😊😊

@peterodinibueze 3 года назад

Torques as Moment comes from German ; PHYSIK Produkt aus zwei Größen, deren eine meist eine Kraft ist (z. B. Kraft × Hebelarm) meaning; PHYSICS Product of two quantities, one of which is usually a force (e.g. force × lever arm)

@Milespro2346 11 лет назад

You want to break the force vector down into its component forms. (x,y and z if you are feeling adventurous). Usually this is found by using trig functions on a diagram of the system, where you treat the actual vector as the hypotenuse, and solve for the sides (they will be perpendicular to an axis). So by using the x or y component of the force you find what amount of force is actually being applied perpendicular to the object.

@necedm 14 лет назад

Cool demonstration... just fyi.... "moment" is a term used to describe and idealized force that is curved in a circle... However in real life of course there is no such thing as a "curved force" and moments are actually just forces acting about moment arms.. hence if you dont care about the actual force that creates the torque, sometimes you'll just hear "moment" instead... When talking about torque, your implying that the force and the moment arm are indeed important.

@iitwala01 4 года назад

Good one... IIT wala se bhi padh lo

@radaferb 12 лет назад

That's really helpful thank you (: better than my physics teacher! Subscribed (:

@somdeepbose8466 3 года назад

What is the difference between torque and moment?

@carultch 2 года назад

Physically, torque and moment are the same thing, and physics will exclusively use the word torque. In Engineering, the difference is that moment is perpendicular to the axis of rotation (causing bending), and torque is parallel to the axis of rotation (causing twisting). It helps to have both terms when both concepts coexist in the same problem. Moment's full name is "moment of a force". Moment in general means quantity multiplied by distance from a reference point. When it is force, that becomes the moment of a force, which is the same thing as torque.

@lewiscmbrit 13 лет назад

@khanacademy Isn't displacement a vector and distance is the scalar quantity?

@jt21419 9 лет назад

"Moment arm", I think "arm" is from the terminology regarding levers ("lever arm"). Moment is a combination of a physical quantity and a distance ("moment of force" is synonymous with "torque").