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
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.
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.
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
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!!
@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...
hoohooo...!!! sound of celebration....thanks..now i got it...simply " torque is the turning effect of force" isnt satisfactory...there is still uncertainty in the definition itself...it makes me believe that torque is simply turning/rotation but that doesnt feel right in some cases...But now, you just cleared my doubt about torque...according to you, torque is simply a force that makes something turn/rotates about its axis of rotation. torque rotates a body...
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 :)
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
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!!!!!!!!!!
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.
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).
@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
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)
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."
@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.
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
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 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.
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.
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
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)
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
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.
"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").
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....
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 .
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)
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.
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.
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🤗
@@Tushar_roy11 physics using calculus?? Blasphemy!
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
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
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!!
I am using your videos to supplement my MCAT studying. 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
@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...
u help me in my difcal now ur helping me in my physics.. men ur very kind..
how can i pay ur gratitude..
hoohooo...!!! sound of celebration....thanks..now i got it...simply " torque is the turning effect of force" isnt satisfactory...there is still uncertainty in the definition itself...it makes me believe that torque is simply turning/rotation but that doesnt feel right in some cases...But now, you just cleared my doubt about torque...according to you, torque is simply a force that makes something turn/rotates about its axis of rotation. torque rotates a body...
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 😭
THANK U SO MUCH. I have a physics test coming up, this helped alot.
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???
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
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
You've taught me more than my construction teacher did in three 30 minute lectures
Im a junior in college studying biological engineering and these videos are awesome reminders
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!!!!!!!!!!
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 !
@khanacademy No. Since Direction is not associated with the distance covered, it is a scalar. Displacement is a vector quantity.
Thanks Sal, my physics teacher just confused me so much... 😀
OMG! It still holds true in 2020.
Bruhh..
😂math is timeless my guy
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.
Me: getting up to leave
Teacher: Why are you leaving?
Me: Wrong class. I signed up for introduction to Twerk.
As usual I love science, I love Sal. Outstanding explanation!
+Vln Murthy Yeah, physics is awesome, huh?
I like to visit you one day and thank you for everything I learned and learning from you.Hus.Australia
rip Australia
It's not just about force and displacement being perpendicular to each other... it's the dot product
very well explained , thank you)
why it will rotate around center of mass, and not simply undergo translatory motion, when the rod isn't fixed at a point
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).
Your way of teaching is amazing, love it
@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
I love the colors! Thanks a lot. You should teach my college course.
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)
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."
This is so helpful👍
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).
@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.
this was helpful thank you
I wish my professor could teach like you cuz you put it in a easy way
i just ike how that word sounds.... torque, so cool!
Thank jegus for this channel. If this didn't exist, I would've failed my physics final.
jegus
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
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 actually I believe distance is a scalar. Displacement is a vector.
@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.
those explanations were great though nice work sal
Steady I Really Like This Video Introduction to Torque
Thank you for the explanation !!
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.
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
Excellent video, thanks for the closed caption.
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)
Khan you're a lifesaver!
Very helpful. Thank you.
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
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.
Much better than the way my physics professor taught it.
"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").
Thank you for your videos.. it is very helpful on my review classes..
"You know then that the net twerk is zero"
That was literally what I personally heard
I am from future 😂😂😂2021
It's interesting to read 8-12 years old comments here 😅
it helped a lot
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....
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 .
thank you GK for your kind reply..
@khanacademy 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
Good one... IIT wala se bhi padh lo
hell yeah bro!
Good explanation
@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.
Love this video. Helped me a lot
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 Sal, I am pretty sure distance is NOT a vector....It has no direction.... DISPLACEMENT is a vector, not distance
If your teacher can't, Khan can!!
thank you
What is the difference between torque and moment?
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.
I only did it because you said so. It feels so weird, like a "Phantom limb" effect.
thxx bro u were helpful😆😆
Great explanation Bro! Thank u
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
THANK YOUUU!
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.
thanks.
Superb!
Sal, I love physics but i am just can't understand it as fast as math
i love khan academy
Why cant university professors teach? Sometimes, i wish i was still in high school, at least the teachers there actually teaches.
Khan you're my Hero
thanks!
Great explanation !
😊😊😊😊😊😊😊
thank you so much
Dude this was soooo helpful :D
great explaination :D thank you
thank you very much (:
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.
Torque is essentially work, because W = τθ
By that logic, arc length and radius are the same.
T(torque)=Fd is the same thing as Torque=r(distance from force and pivot point)Fand Sin(theta) right...?
actually, work=force*displacement..... and torque=force*distance.
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?