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

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Introduction to moments. 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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Пікірлер: 364
@borisjohnson32
@borisjohnson32 5 жыл бұрын
*Clockwise:* ↩️ *Counter clockwise:* ↪️ Hope this helped Edit: (1 year later) Did i seriously just tell people on the internet what clockwise and counterclockwise is?? LMAO
@kaushikkalesh1678
@kaushikkalesh1678 4 жыл бұрын
Seriously? But thanks for the good Intent
@spontaneouspotato133
@spontaneouspotato133 4 жыл бұрын
Boris take away tax innit
@itsjustanapple5452
@itsjustanapple5452 4 жыл бұрын
Cant you just think about a clock in your head.
@Cube_Box
@Cube_Box 4 жыл бұрын
@@itsjustanapple5452 for people who were born in the digital age and never seen a ⏰ they'll find this really helpful
@Rianajay
@Rianajay 3 жыл бұрын
Here I am a year later laughing at what you said. LMAO
@elle9030
@elle9030 6 жыл бұрын
he confuses clockwise and anticlockwise in the end but overall he explains everything else perfectly
@88GTA
@88GTA 3 жыл бұрын
Tryna be my tutor? 😏
@zolanhlangulela947
@zolanhlangulela947 3 жыл бұрын
He did correct it in the end..He noticed it
@hippo1503
@hippo1503 2 жыл бұрын
@@zolanhlangulela947 he said “confuses” not wrong
@michellerstewart7
@michellerstewart7 2 жыл бұрын
I came here to see if I was crazy. I was so confused, lol
@niconikko
@niconikko 13 жыл бұрын
"It always becomes a lot easier when you do a problem, except when you try to erase things with GREEN."
@dasumma1
@dasumma1 4 жыл бұрын
8 years ago and someone is probably seeing your comment for the first time
@samuelhugo467
@samuelhugo467 4 жыл бұрын
9 now and I was just the 5th person to like it
@felixling8976
@felixling8976 3 жыл бұрын
4:29
@EesaSalmanKakakhel
@EesaSalmanKakakhel 3 жыл бұрын
Nico, are you still there, how old are you
@glitchy_star_classes6276
@glitchy_star_classes6276 3 жыл бұрын
Eesa Salman Kakakhel 18 years .. you?
@nmq3b
@nmq3b 15 жыл бұрын
"why did I write down mechanical?" lol. His unintentional humor makes it really fun to watch.
@seungseungminji
@seungseungminji 3 жыл бұрын
How did life treat you? How was school?
@Davidow1
@Davidow1 9 жыл бұрын
I hope this and all other physics videos gets updated to HD and have all their mistakes fixed. I'm still loving KA though and will keep donating!
@Datagnan95
@Datagnan95 11 жыл бұрын
did he cnfused on clockwise n anticlockwise?
@SarcasticxLiar
@SarcasticxLiar 10 жыл бұрын
Yess omg i was so confused
@AmiraDreams
@AmiraDreams 10 жыл бұрын
yep
@Abss0966
@Abss0966 9 жыл бұрын
+Amira Lam. hi
@inesmonteiro7250
@inesmonteiro7250 7 жыл бұрын
Yes i think he did
@libinchen9899
@libinchen9899 6 жыл бұрын
I mean he did, but he clarified the method we should use for this type of problems! 😂
@Scipio-Africannabis
@Scipio-Africannabis 5 жыл бұрын
Hilarious how you know all this detailed physics stuff yet can't figure out which way a clock-hand moves. Great video though, very helpful!
@nazirelahi9968
@nazirelahi9968 6 жыл бұрын
You literally are my physics exam savior
@jstinlee
@jstinlee 9 жыл бұрын
The day that you can torque better than Miley Cyrus
@AlejandraRodriguez-rn1zp
@AlejandraRodriguez-rn1zp 8 жыл бұрын
+Kun Seung Lee better than Rihanna
@Bilnuran
@Bilnuran 8 жыл бұрын
+Clara “mylove2345” Torque Torque Torque Torque Torque he said me haffi TorqueTorqueTorqueTorqueTorque! xD
@matimuyerhutimsondlane9226
@matimuyerhutimsondlane9226 6 жыл бұрын
True that Mr Obama
@do._.daboss4828
@do._.daboss4828 4 жыл бұрын
Nobody: Comments: keeps saying he confused between clockwise and counter clockwise non stop Note: am I the only one who writes/says anti clockwise rather than counter clockwise?
@stephaniemalik6108
@stephaniemalik6108 10 жыл бұрын
twerk.......... now im understanding moments of a force!! thank you Khan
@OmriKipi
@OmriKipi 16 жыл бұрын
"i don't know... lets say its 2 " - damn , did i laugh so much :)
@YeshuaIsKingofKings
@YeshuaIsKingofKings 13 жыл бұрын
Sal, you are great. Just a little correction: Im afraid that you did confuse the clock- and counter clockwise directions at about 10 minutes. But Its common sense. Best regards from Serbia
@xconwing
@xconwing 15 жыл бұрын
very nice, this is a review for me but your confusion of counter-clockwise / clockwise every now and then is funny, making the tutorial quite refresh and not sleepy
@pruthviraj9917
@pruthviraj9917 8 жыл бұрын
though it is helpful but presentor have confusion in clockwise and anticlockwise
@Ridegucci
@Ridegucci 13 жыл бұрын
mate in a short video ive learnt more from you than my physics teacher.... you made it so easy to explain..
@BaronMorte
@BaronMorte 15 жыл бұрын
Sal...you are the man. Thank you.
@heavymetaldeath4life
@heavymetaldeath4life 13 жыл бұрын
@vladuz1001 Always remember this formula: F=ma where 'F' is measured in Newtons(N), 'm' is measured in Kilograms(Kg) and 'a' is measured is Metres per second squard(M/s^2). 'a' is usually 9.8m/s^2 when you're talking about forces acting perpendicular to a surface. If we apply F=ma to your problem: 1,294(N)=m(Kg)x9.8(m/s^2) You're trying to find the mass, or 'm', so we divide both sides by 9.8 to make 'm' the subject. 1,294/9.8=m Therefore m=132Kg
@theblunderkegs2334
@theblunderkegs2334 7 ай бұрын
oh my gosh I was 4 when this video came out, now I'm in college and this guy has helped me get through calculus, chemistry, and physics many many times. thank you sir you have been a blessing in my life
@mexicanmilky123
@mexicanmilky123 14 жыл бұрын
Good Video, Confused about The CCW and CW parts until you corrected it at the end. But still very helpful
@pawpawbear1175
@pawpawbear1175 8 жыл бұрын
guys he mentions that he kept mixing up clockwise with counterclockwise near the end just go with clockwise and counterclockwise as you would. he was just mixing them up on accident
@av_naturasmr
@av_naturasmr Жыл бұрын
Moment is simply just a rotating force around a specific point/pivot. You can start with this simple meaning
@Montecation
@Montecation 12 жыл бұрын
Look its easy, just think about trigonometry: your angle is positive as it goes counterclockwise and negative as it's going clockwise. if you can just keep that image in your head, everything becomes pretty straightforward as far as the direction of torque goes.
@leechmaster21
@leechmaster21 11 жыл бұрын
Thanks Sal, I remember I was terrible @ this stuff in high school. Now I'm at university and I need to know this stuff for a Biomechanics unit, so much clearer now.
@rolandsaucier1006
@rolandsaucier1006 2 жыл бұрын
I got it ......and, as a teacher myself, I have some sympathy for the guy here. Some days are just harder than others. LOL.
@0113slimshady
@0113slimshady 11 жыл бұрын
Sal I think you may have just saved my life! THANKS SOO MUCH!
@singh123416
@singh123416 9 жыл бұрын
god bless khan academy
@amaadulhaq4319
@amaadulhaq4319 10 жыл бұрын
U explain so nicely and clearly
@bballer10590
@bballer10590 11 жыл бұрын
Thank God! I'm so happy Dr. Khan made a video!!
@J001ean
@J001ean 12 жыл бұрын
It was easy for me to understand because i saw your comment prior to watching :D
@makd7659
@makd7659 7 жыл бұрын
How do you determine the unknown force as clockwise or anticlockwise? Or you just assume
@PianoWallaby
@PianoWallaby 16 жыл бұрын
You say clockwise and counterclockwise backwards at 11:00. But thank you for the great video[s]!
@morvaridahmadijah6999
@morvaridahmadijah6999 6 жыл бұрын
You're amazing for refreshing my pre-university memory keep it up :D
@arichujo6063
@arichujo6063 2 жыл бұрын
omg the clockwise and counterclockwise stuff was so frustrating. here's a simple trick, clockwise goes in the same direction that a clock moves. lol.
@guywthclss
@guywthclss 3 жыл бұрын
QUESTION - Any explanation of "moment" or "moment connections" must start with the etymology of the term "moment" which is crucial for me when I try to understand anything. So any layperson, when they think of the term "moment" is in reference to time. A "moment" of time. So now that we are apparently repurposing the term "moment" for torque etc can you explain why it is called a "moment" to begin with? How is the term "moment" in reference to time used here or are we redefining the term specifically for physics / Engineering?
@DOROnoDORO
@DOROnoDORO 2 жыл бұрын
take a shot every time Sal mixes clockwise and counter-clockwise
@f8tal_156
@f8tal_156 6 жыл бұрын
oof almost a million people saw sal getting confused with clockwise and counter clockwise xD if you view the same video on the ka website a small pop up corrects his mistake
@notslo
@notslo 15 жыл бұрын
Excellent teaching style. Thanks.
@ShiftnoteProductions
@ShiftnoteProductions 6 жыл бұрын
basically the closer the object is to the pivot... the more effort ( force ) required ?
@davemcquire504
@davemcquire504 11 жыл бұрын
I'd love to see a lot of beam deflection problems using calculus. Simple span two point beams with multiple loads and cantilevers - but not all at once. Thanks so much love your work!
@someonetoogoodforyou
@someonetoogoodforyou 12 жыл бұрын
Hey Sal, I've been looking at dozens of videos and wikipedia pages, but I can't find a formal proof for why M = Fr. Can you do a video describing the formal proof behind this formula? Cheers
@artroaster9886
@artroaster9886 Жыл бұрын
its not angular momentum its troque for angular momentum it will be momentum times the radius
@AngelusLabyrinth
@AngelusLabyrinth 14 жыл бұрын
Ah! I sure wish I found this channel earlier! But thanks too anyway.
@imogenburn7549
@imogenburn7549 12 жыл бұрын
your better at teaching than my science teacher
@joaonogueira3401
@joaonogueira3401 4 жыл бұрын
finally I undesrstood thanks Sal
@neelamsarma5076
@neelamsarma5076 10 жыл бұрын
wonderful and a highly conceptual video......simply amazing......like ittttttt....!!!
@thetiger693
@thetiger693 11 жыл бұрын
If I screwed up a video explaining a simple concept such as this as badly as this guy did I would re-do it.
@TheNigttimeNightmare
@TheNigttimeNightmare 4 жыл бұрын
this. was. twelve. dang. years. ago. and yet his way teaching never fails to teach me : )
@Fywl92
@Fywl92 12 жыл бұрын
LOL dude! Nice lesson! I actually learn a lot + it is fun. I love it, thanks a lot, I got a hard time understand this.
@zikmir007
@zikmir007 6 жыл бұрын
RIP Clockwise and Counterclockwise.
@overreactiontime6270
@overreactiontime6270 8 жыл бұрын
Its actually really nice thanks
@hatemsaad3421
@hatemsaad3421 8 жыл бұрын
you're just overreacting
@baydood510
@baydood510 12 жыл бұрын
God bless you Sal....I have a nephew who looks like you btw
@OnimisiAlao
@OnimisiAlao Жыл бұрын
Hello Sir! I have a question regarding the direction of a force. How can I determine if a force is clockwise or counterclockwise? Could you please provide some guidance or resources on this topic? Thank you in advance for your help!
@TheJJJJJasonXRX
@TheJJJJJasonXRX 12 жыл бұрын
angled ones u need to use cos or sin to calculate... and u can assume clockwise as any direction and counterclockwise as the opposite direction of the clockwise... stop complaining, he is good
@amethyst452
@amethyst452 12 жыл бұрын
AMAZING!, thanks sooo much. Just started this topic in class and my teacher kinda sucks. This made things so much clearer, don't worry about the clockwise and counter clockwise stuff, i understood it :D
@imedyana
@imedyana 14 жыл бұрын
thanks a lot for the video. great help to students like me.
@daniellaokafor6970
@daniellaokafor6970 3 жыл бұрын
You still alive?
@Blueknightex
@Blueknightex 15 жыл бұрын
Oh shoot! I gotta watch this! I'm so lost @ my Engr. Mechanics right now and I don't get the magnitude of the moments stuff!
@verza5042
@verza5042 4 жыл бұрын
The explanation is very comprehensible and we'll simplified, but the video is only available in low resolution..
@mashrefatarannum8983
@mashrefatarannum8983 4 жыл бұрын
Dear Salman , plz dont bother that you clouded the directions in the last case. Know that you're an amazing teacher and we love you a lot.
@shadowknight00
@shadowknight00 4 жыл бұрын
Legend has it that under those black rectangles, there is infinite knowledge
@onlyAerik
@onlyAerik 15 жыл бұрын
11:00 24N*8ft would work very nicely.
@SuperGamerYoBros
@SuperGamerYoBros 8 жыл бұрын
How is that counter-clockwise ?
@mdhussain363
@mdhussain363 8 жыл бұрын
because we get +ve value of F .. and initially we assumed that it will be in counter-clockwise
@naominene6554
@naominene6554 7 жыл бұрын
Lifesaver. About to write a test and you have no idea how much confusion you saved me from. @MdHussain
@mdhussain363
@mdhussain363 7 жыл бұрын
😊😊
@JordanMorris-nzer012-_-PSN
@JordanMorris-nzer012-_-PSN 7 жыл бұрын
I don't get, and I have a test next week. Help pls!!! @Md Hussain
@SharkRockstar
@SharkRockstar 7 жыл бұрын
How'd your test go? And just for advice: keep searching on UTube & you'll find success. X''S
@christopherhan9756
@christopherhan9756 10 жыл бұрын
for the last time, clockwise = --> this way counter clockwise=
@rabalac99
@rabalac99 12 жыл бұрын
he made me pass my grade 9 exam now im doing my BIG School leaving Exams lets see if he'll do the job now
@Cube_Box
@Cube_Box 4 жыл бұрын
8 years later, how are you doing man??
@theslingmethod
@theslingmethod 2 жыл бұрын
Brilliant explanation. We got the clockwise/anti-clockwise, thanks again! 👍
@tasinal-hassan8268
@tasinal-hassan8268 8 жыл бұрын
12:10 why are you multiplying the variable F with anti-clockwise moment 6*3?
@thatnewguy23
@thatnewguy23 13 жыл бұрын
@goldensilverstar He corrects himself at 13:36 but the concept gets across if you don't get stuck on that one detail.
@Saudibodybuilding
@Saudibodybuilding 9 жыл бұрын
plz are you sure about what u said in your Example < clockwise and counter clockwise >!!!! I think you reflected the trends ........who is agree with me?
@TerenceYipMusic
@TerenceYipMusic 8 жыл бұрын
+Taj Alhashem as long as you are consistent with your direction, the result would not really matter.
@KeijiJohnLibadisos
@KeijiJohnLibadisos 8 жыл бұрын
he's wrong .. that's not counterclock wise
@puneetpathak5840
@puneetpathak5840 8 жыл бұрын
clock was screwed and so the directions
@careerlid7078
@careerlid7078 7 жыл бұрын
i
@everydaynews2162
@everydaynews2162 6 жыл бұрын
Me too
@Nandine2
@Nandine2 16 жыл бұрын
oh my god, thank you, thank you, thank you.
@lyndalandzeh9766
@lyndalandzeh9766 12 жыл бұрын
he just mixed up everything through out the video and he corrected it as from the 13:21 ,coz if you actually take a clock and try to compare the movement of the forces with the clock hands' mov'ts,you will realize that the 10N and 50N forces actually move in a ''CLOCKWISE'' direction,and the 5N ,6N, F forces go ''ANTICLOCKWISE or COUNTER CLOCKWISE''...hope this was helpful enough!!
@bondyota90
@bondyota90 13 жыл бұрын
@jamieskill. 10 is an estimate for g. Since 10 is much easier to use mathematically it makes sense to round to 10 instead of multiplying or dividing everything by 9.81, especially if taking a test without a calculator.
@rhshovan
@rhshovan 4 жыл бұрын
THANK YOU SO MUCH....
@lordloki86
@lordloki86 12 жыл бұрын
Hilarious how he mixes up counter clockwise and clockwise, even when he acknowledges he's done it!! :)
@xensationss
@xensationss 13 жыл бұрын
this was very good.. i get it now!!lol.. im in 10th grade and when im studyings physics for exams this is so helpful!! thanks=)
@libinchen9899
@libinchen9899 6 жыл бұрын
Come on guys, understanding the graph and method is wayyyyy better than complaining about clockwise and counterclockwise, this this case, u just need to know the force direction is different and put them in opposite side of the equation.
@Mzimzim
@Mzimzim 15 жыл бұрын
You might want to check your clocks. I think they're spinning in the wrong direction.
@technodaisy18
@technodaisy18 4 жыл бұрын
For all of you guys confused wondering if he got clockwise and counter-clockwise mixed up, he didn't. That's how torque works.
@LichKing887
@LichKing887 12 жыл бұрын
Same with me, I really am having problems about the rotation, whether its a C or a CC.
@ahmed12188
@ahmed12188 13 жыл бұрын
@vladuz1001 m.g=1,294 N where g (the gravitational force =9.8 m/sec^2 ) so divide the force by g to get the mass
@mcpel1055
@mcpel1055 10 жыл бұрын
There's a problem with rotation direction but the computation is correct since it is to be equated to zero for the system to be in equilibrium.
@carbon273
@carbon273 7 жыл бұрын
just use right hand rule for the sign convention of clockwise and counterclockwise. I finished this in half the time it took time to explain
@zckhor1778
@zckhor1778 6 жыл бұрын
Thanks a lot!
@Aboalmaaly
@Aboalmaaly 13 жыл бұрын
thanx mate!
@harrytuttle4069
@harrytuttle4069 8 жыл бұрын
Thank you so much!
@NerakCraze430
@NerakCraze430 12 жыл бұрын
oh thnx god, this video save my live!!!
@ChristaMulliganPEng
@ChristaMulliganPEng 13 жыл бұрын
Clockwise = "-" and CCW = "+"are just conventions. Just like we consider "up" to be "+" - who decided that?...These questions work even if you assume clockwise as "+", as long as you are consistant. Every Teacher/Instructor/Prof will teach the concept slightly differently. Best to keep perspective and take these concepts and apply them to your course notes. Yes, he did mess up he clockwise and CCW, but he is hardly the first to do it - Draw good FBD, assume forces and use Equilibrium equations
@appletime20
@appletime20 11 жыл бұрын
thanks, this helped alot :)
@emmanueladebayo3564
@emmanueladebayo3564 4 жыл бұрын
Thanks 😊
@EclipZeMuzik
@EclipZeMuzik 6 жыл бұрын
dude you're amazing i love this!
@gavincedana7781
@gavincedana7781 9 жыл бұрын
i was confused in your video.. please make it better and correct for the next time around.. Thank you..
@renewableenergy78
@renewableenergy78 11 жыл бұрын
THANK YOU!!!!!!!!!
@evolvewithbaha187
@evolvewithbaha187 4 жыл бұрын
Clockwise ↩️ Anti-clockwise ↪️
@kiannaking2565
@kiannaking2565 7 жыл бұрын
thanks bro!, you helped me a lot, keep up the good work!!!
@BobSmith-fg6wi
@BobSmith-fg6wi 12 жыл бұрын
thx! i understand now ;)
@KeijiJohnLibadisos
@KeijiJohnLibadisos 8 жыл бұрын
that's not counter clockwise 😒
@pranshusingh2000
@pranshusingh2000 6 жыл бұрын
Please make an HD video of this
@imedyana
@imedyana 14 жыл бұрын
thanks a lot.
@ceesingharora
@ceesingharora 13 жыл бұрын
good' i understood'
@mahmoodmahmoo1033
@mahmoodmahmoo1033 11 жыл бұрын
I like this guy he is much better than my stupid teacher
@jeremyenoria8933
@jeremyenoria8933 8 жыл бұрын
it really helped me in some points but when he pointed the clockwise and counterclockwise ...
@onlinearcherychallenge2440
@onlinearcherychallenge2440 8 жыл бұрын
Would you do a presentation on torque created on a archery shot where the hand meets the bow?
@sajjadulislam8651
@sajjadulislam8651 8 жыл бұрын
sir didnt u make a mistake in 10:06 as the moments should be clockwise in that direction...
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