Introduction to torque | Moments, torque, and angular momentum | Physics | Khan Academy
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- Опубликовано: 3 мар 2008
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An introduction to torque. Created by Sal Khan.
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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
total agree!!!!!!!!!!!!!11
Yes. Distance is specified by a magnitude and direction.
This is the first comment for this video.
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..
@@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.
Good basic explanation. Wish i could find videos that actually match the rigor of my physics class :/
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.
@@fasihussaini8554 hahaha 😆 when you don't know what torque means physically and you are studying physics and talking about calculas🤗
@@LFCtushar physics using calculus?? Blasphemy!
Me: getting up to leave
Teacher: Why are you leaving?
Me: Wrong class. I signed up for introduction to Twerk.
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!!
>Desperately look for videos explaining the topics of interest.
>See Khan Academy video
>smile on my face
Synochra because you r dumb
Introduction to Torque gets over half a million views.. talk about an outstanding job!
A million now.
Pixel
This video has more views then pixel at its max resolution :D
@Drik Sarkar you meant 1.3 million.
@@pikmin4000 you meant 1.4 million
I am using your videos to supplement my MCAT studying. Thank you so much!!
Your way of teaching is amazing, love it
Miley's favorite Physics topic.
Satoru Iwata Flop joke try again next time
Don't listen to the haters. I laughed.
Jordan Heinemann Thanks!
Hi ...after 5 years😂
What???
You've taught me more than my construction teacher did in three 30 minute lectures
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!!!!!!!!!!
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
Im a junior in college studying biological engineering and these videos are awesome reminders
THANK U SO MUCH. I have a physics test coming up, this helped alot.
u help me in my difcal now ur helping me in my physics.. men ur very kind..
how can i pay ur gratitude..
I love the colors! Thanks a lot. You should teach my college course.
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
Thank you for your videos.. it is very helpful on my review classes..
very helpful! thanks a lot
Great explanation Bro! Thank u
As usual I love science, I love Sal. Outstanding explanation!
+Vln Murthy Yeah, physics is awesome, huh?
great explaination :D thank you
Thank you for the explanation !!
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
Thanks Sal, my physics teacher just confused me so much... 😀
Excellent video, thanks for the closed caption.
Love this video. Helped me a lot
those explanations were great though nice work sal
Very helpful. Thank you.
I wish my professor could teach like you cuz you put it in a easy way
@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
Steady I Really Like This Video Introduction to Torque
this was helpful thank you
You're voice is so soothing at 12:30am :)
your*
Your*
12:57 am, exam tomorrow :p
Oh God
Woahh found the comment at exact 12 30...! Couldn’t agree more !
I like to visit you one day and thank you for everything I learned and learning from you.Hus.Australia
rip Australia
i just ike how that word sounds.... torque, so cool!
"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").
Great explanation !
😊😊😊😊😊😊😊
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 :)
Your comment is 7 years old?
-feel old yet xD
@@hashirscam you too
@@leungkonrad3215 Lmao 😭
This is so helpful👍
"You know then that the net twerk is zero"
That was literally what I personally heard
Thank jegus for this channel. If this didn't exist, I would've failed my physics final.
jegus
I seriously think the colors help me from zoning out..it's like light bright on steroids....and they really help distinguish different concepts.
Hii after 11 years 😂😂😂😂 what are you doing nowadays
@@musicaldarpan629 Currently on television and earning my Ph.D.
@@drevilpolo7 :D
lol a 14 year old comment dem
... ig i was 2 back then
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."
thank you very much
OMG! It still holds true in 2020.
Bruhh..
😂math is timeless my guy
Khan you're a lifesaver!
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.
thank you so much
it helped a lot
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.
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)
Dude this was soooo helpful :D
@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...
It's not just about force and displacement being perpendicular to each other... it's the dot product
THANK YOUUU!
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.
@khanacademy No. Since Direction is not associated with the distance covered, it is a scalar. Displacement is a vector quantity.
why it will rotate around center of mass, and not simply undergo translatory motion, when the rod isn't fixed at a point
Me: Realizing that I am watching this on youtube and not getting any arbitrary energy points...
Thank you
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?
Much better than the way my physics professor taught it.
thanks!
I am from future 😂😂😂2021
It's interesting to read 8-12 years old comments here 😅
thank you very much (:
Good explanation
hell yeah bro!
thxx bro u were helpful😆😆
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.
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.
Khan you're my Hero
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).
@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.
3:57 Momentum
concept in useful
thank you
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 ?
i love khan academy
@khanacademy Isn't displacement a vector and distance is the scalar quantity?
woah i get itttttttttttt!!!!!!!!!!!!!
thanks.
i like how this is a physics video yet 75% of the comments below are completely irrelevant lmao
Force and distance vectors HAVE to be perpendicular?
@saadnizamani does "the moment of a force" sound like a form of energy to you?
could not have explained better!!!😍😍😍
@khanacademy actually I believe distance is a scalar. Displacement is a vector.
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?
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)
@@ThePhoenix042 najs
Superb!
Watched this to try to get a better understanding of how planes work in KSP, now I'm even more confused... The equation for torque shows that force increases from the distance from CoM, yet in KSP having your center of air pressure closer to the CoM, which should result in less force, somehow makes the planes rotate FASTER than if you had that same amount of air pressure force further from the CoM. Only way I can figure this out is if it's all counter-intuitive, that the forces ARE greater the more distance from the CoM, but that when rotating planes/rockets, what matters more for rotational speed is the distance of said force from the CoM
why is that, if we push a door from the corner most side we have to apply less force in order to rotate it by an angle ?. I know that the torque will be more but it is way to mathematical torque = force x length of the arm . I don't want to know it mathematically but physically .
9:00 makes me think of brain vs brawn :) the weaker guy has more brains, so he uses more leverage xD awesome video again
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).
nice share.
is torque the same as work. it is a vector but has the same dimensional formula
@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.
After about the 12th video of Khan Academy, I hope everyone realizes to put this guy on speed X 2. Settings-speed-2.
2x speed is too fast to catch up with
lol i put mine on .75x speed
@khanacademy
Isn't distance a scalar quantity and displacement is vector?
wow. i love physics, and u make it fun! if u teach tell me where and ill go to ur class! hahha excellent job. very clear and understandable
Omg are u alive now
@@HayDayEveryday wow this was 11 years ago.. I am still here lol and still love physics
@@21beal21 did u just reply me after 11 years hollyyy cowwww omgg!!! LOLLL u made my day!!!
wow 12 yr old comment