Moments (part 2) | Moments, torque, and angular momentum | Physics | Khan Academy

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2 more moment problems. 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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2 окт 2024

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Комментарии : 157

@jstinlee 8 лет назад

dw you're still 1000x better than my college physics teacher

@shamdamdoobley4266 9 лет назад

im not gay but i think i love you! you saved my life

@el_chico1313 9 месяцев назад

😂

@johnchong1009 11 лет назад

3 weeks of college in 10 minutes. I Love KHAN academy

@justinsankar1164 5 лет назад

You mean highschool

@nsarbselectro 2 года назад

@@justinsankar1164 depends when you took your physics course

@cocorosalie2666 10 лет назад

Sal's sneeze made my cat wake up hahahaha

@drenikbaftiri3925 9 лет назад

your a life changing human being who is changing futures for As students like me I am very greatful for your videos thank you so much x

@renatusdev 5 лет назад

If the origin is in the middle, why are the left side distances not negative? And what happened to clockwise being negative Torque and counterclockwise being positive torque?

@urano4810 4 года назад

I believe they are negative, if all the forces were on the same side of the equation because the total would have to be 0 since there is no movement. But when you equate the forces on one side to the other, you're taking those negative values and adding them to both sides to cancel out the negative values and you're left with all positives. For example: -A+B=0 Therefore B=A Edit: I know this is 4 months late for you but maybe someone with the same question will read it in the future.

@jsleamer2046 8 лет назад

rip 5:19

@Fittiboy 6 лет назад

my sneakers dude

@devonsheehan249 7 лет назад

Saving my grades for 9 years running

@NeoNik21 10 лет назад

HELPED ME A LOT FOR MY EXAM TODAY!! THX

@walidzein1 8 лет назад

Bless u 5:19

@blikzz2387 9 лет назад

5:19 tornado!!!!!

@kenjiroumiyamoto1432 8 лет назад

Table flip @ 8:44

@virupannamedikinal Год назад

Absolutely enjoyed it.Thank you so much

@FastFiveForever 13 лет назад

Man, we all appreciate what you're doing for us KhanAcademy, and i want to personally thank you as you got me through with chemistry, biology, and now hopefully, engineering. Thank you very much bro!

@eddydrouet1888 8 лет назад

but... but... I thought tables had 4 legs... :'(

@CanoManuelGonzaga 7 лет назад

Some tables have one leg that run through all the edges of a table.

@fpseli117 14 лет назад

@ChillerPhil me too this guy is great but i wish he could do a little more complicated examples

@melrakan 9 лет назад

This is actually Statics, right (or the first problem at least)? Could you somehow indicate this in the title? Because it's a subdivision of mechanics.

@OmriKipi 15 лет назад

just learn something that 4 hours lecture didn't managed to do , thanks :}

@TuberKMT 4 года назад

Love you; love your videos. Thank you for the awesome help you provide on some tough topics. Now, having said that, I don’t think this is correct. The CCW forces actually add up to 70 + 10F, right?

@LwaziNzimande 9 лет назад

Thank you. That was helpful.

@Chris-pf9vl 9 лет назад

I think you just saved my life...much appreciated man!

@ramsey180 12 лет назад

I love you man, seriously i want to meet you and say i love you .. thanks for the great work

@xanfiler6366 8 лет назад

this video saved my life...

@pratyushamutyala9022 6 лет назад

In the first see-saw problem, the force is supposed to be applied in the counterclockwise direction. As a rule of thumb, clockwise is always negative and counterclockwise is positive, right? Therefore the final equation should have been -280Nm + 430Nm. This gives us 150Nm which divided by 10 m gives us 15 N in the counterclockwise direction. Please let me know if I'm wrong... thanks.

@markkoehr5003 6 лет назад

Pratyusha Mutyala I believe if you are setting them equal to each other you keep both sides positive. That way when you move them to one side it equals zero.

@skylit93 13 лет назад

yes , clockwise and counterclockwise again :) . .

@Dan-bg5fm 8 лет назад

that sneeze though lol

@whatisayoutubehandlebro 5 лет назад

A table thay is 5 meters wide 3 metwrs tall is only 2kg 😂😂 great vid otherwise!

@dedly13 13 лет назад

holly crap i love your vids

@sufia_z 7 лет назад

You're 1000x better than my physics teacher (grade 8) 😂

@ahmedismail8017 9 лет назад

0_0 i just see big numbers. With alot of other numbers which Makes my brain explode and in the end i like the video but dont understand it ( i hate physics)

@jadakhan173 3 года назад

yep my speakers definitely blew up with that sneeze but both videos really helped me in school thanks a lot keep up the good work

@td6063 10 лет назад

that sneeze really blew out my speakers. I'm glad i wasn't using earphones, though.

@kkngenomesho7744 6 лет назад

i have headsets on... luckily the volume was low...

@mrvlhs 14 лет назад

I don't think you can calclulate momentum with a box because of the contact surface being so extended, it isn't the same thing as calculating it with a "point force" wich has virtually no surface (like say the tip of a finger in a pencil). Can you confirm?

@hennanabi1343 11 лет назад

This amazing tutorial has given me hope! Yeay I understand moments and I won't be a complete failure!! THANK YOU KhanAcademy for helping us in a way only you can.

@Twisted_Logic 12 лет назад

That is NOT a book I'd like to carry around. Fuckin' heavy.

@rogertiger 15 лет назад

no, just how to calculate the center of mass of amny objects, not its gravitational atraction.

@goldensilverstar 12 лет назад

FUCK, he burst my eardrums with that fuckin sneeze, nearly shit my pants, thought someone behind me sneezed at my face, fuckin hell ....

@mrvlhs 14 лет назад

@bustdakap Nice, thanks. Too bad it took 6 months for someone to answer this lool :)

@lomoromo5257 9 лет назад

Thank You Sir! :D

@waleedahmadnabeel 13 лет назад

i really appreciate ur videos... there should be some comlicated moment problems solved as well. thanx a ton!

@healthyforyou 15 лет назад

What happens if one weight is on the edge of the table, rather than between the two legs?

@insanegorilla180 11 лет назад

1. A uniform beam AB is 12 m long and has a weight of 400 kg. At A it carries a load of 60 kg and at B a load of 240 kg. Find the center of gravity of the loaded beam. (7.54 m from A) Help me solve this please! :D UR EXPLANATIONS ARE THE BEST!

@redwall1521 10 лет назад

I'm assuming that A is at one end of the beam. It's coordinates is at 0. Therefore, (6 * 400 + 7.54 * 240) / (400 + 60 + 240), which is about 6. So it's at the center of mass of the beam itself.

@MrsRawr94 8 лет назад

+Ian Lim a bit late, but I'm studying this at the moment as well :P we center ourselves in A, so its torque is =0. Then we assume that the mass of the beam is centred so we have 6m x 400 kg x 9,81 . We also add the torque of the mass in point B, that is : 12 m x 240 kg x 9.81. We divide by the total weight which is (400+60+240) x 9.81 and we find (23544 + 28252.8)Nm / 6867 N = 7,5 m which is the distance from point A of the center of gravity of the beam

@kenjiroumiyamoto1432 8 лет назад

Tissue, professor? Thats a lot of torque when it came out xD

@JusShy3526 5 лет назад

Thanks for the help but i don't understand how you got -15 while i got positive 15, also why is it that -15 is a clockwise force and positvie 15 is an anti-clockwise force I just don't get it.

@Jack-er4pc 4 года назад

do you know the difference between clockwise and counterclockwise

@niconikko 13 лет назад

That was the police who's calling. They are suing Sal for sneezing in the video.

@Kimberly-7777 3 года назад

When your using an earphone and his sneeze caught you off guard 😑

@sheldonmachado4578 12 лет назад

we gotta split the force into its vector components....im guessin...

@kaushikkalesh1678 3 года назад

His Math skills is very poor!!! And his teaching also sucked... (See how many corrections he made about his previous videos) But now it's great!!! (From 2012) But his content is always useful!!! Thank You!!!

@AnonTen 3 года назад

That sneeze blew out my sneakers tho

@jdavis6355 7 лет назад

You have redeemed yourself haha ^_^

@alisami6945 6 лет назад

you definitely blew out my sneakers with that sneeze 5:20

@aafrinmuaazah3863 6 лет назад

LOL yeah!!! SNEAKERS!!!! ;P

@nat1XP 9 лет назад

If a vehicle is on a slope and you know its base (1.8m) and height off the slope its centre of mass is (0.8m diahonally not vertically), how do you find the maximum angle x of slope needed to topple it over? The answer is 48degrees but I don't know how Apologies if there's a video on this I must have missed it All I know is to lift one end off ground, Fd > (1/2)Wb I think Friction = Wsinx in eq'm And sum of supports from each wheel = Wcosx Thanks for any help

@peoplelikegamers5024 8 лет назад

I'm confused about the clockwise and counterclockwise stuff. and the arrows are not helping

@HollisKeatingOConnor 8 лет назад

if you imagine all of the problems as being like a see-saw, with the 'point of rotation' being the fulcrum. Imagine what happens when you push down on the right side of it.. The left side rises up. If that were a clock face, it would be going around clockwise i.e going from the stationary 9 o'clock position to 10 or 11 o'clock position..

@goldensilverstar 12 лет назад

Lol at his phone, i thought a train was gonna hit him

@nickve 11 лет назад

You're telling me! Whoever was writing mine must have been drunk..

@luongmaihunggia 6 лет назад

Thank you for making this video and other physics videos, I really need this :)

@benwilliams1889 2 года назад

So, I emailed my professor several times about these type problems after reviewing his lectures and still was confused. I came here, and viola; Instant understanding. You Sal Khan are a master teacher.

@papazizu 12 лет назад

Thumbs up if you said bless you when he sneezed.

@No_W4r5 12 лет назад

what if someone exert a force that have angle?

@buyersguide-ECOM 7 лет назад

great video really helpful thank God my speakers were at low volume cause ur sneeze would have destroyed my ears

@rotflmaopmpqxyz 13 лет назад

Instead of counterclockwise vs clockwise, can you also say that the net torque up on one side equals the net torque up on the other side or the net torque down on one side equals the net torque down on the other?

@sohaib123ify 11 лет назад

For the distance from for the force of 10N Clockwise shouldn't we add up all the measurements cuz we are talking about the siatance form the pivot not the distance from one force to other ?

@abouosalah1741 7 лет назад

my teacher sent me to here .. cuz he knew that he couldn't give us the idea better than you could !

@Hollasino 12 лет назад

Thank you so much. I actually spent $100 today on a tutorial which I got nothing out of and learned everything from this video....

@sohaib123ify 11 лет назад

When there is no hope left, the next day is your exam and you do not understand anything there comes a man with cape made of mathematical equations The Khantributor!!!, he helps you with all chemstry, biology, physics, and math. And ends up teaching better in 10minutes than your teahcer did in 3 weeks, Khantributor there to solve our problems !!

@NGEternal 9 лет назад

For the first example why doesn't it work by assigning all the clockwise forces a negative value (or negative force) and keeping the c-clockwise forces positive? Didn't he mention in a previous video that this is generally accepted to be the case. Assuming he is not wrong with his calculations, which I highly doubt he is, I am forced to reach the conclusion that negatives are for presentation just as the terms counter clockwise and clockwise are, i.e. they are for convention not calculation. I suppose this leads back to the whole F2*d2-F1*d1=0 thing but it is still confusing. Am i correct?

@hrn8935 2 года назад

i know i am late but if you take into acount that then you will also have to use displacement or there position with respect to the origin for example if its 3m left of an origin then with the convention that right it positive you use a -3 i think he avoided that to not mess around with cross porudcts and stuff like that

@jalenpinder7937 6 лет назад

"I apologize if i blew out your sneaker... er your speaker with that sneeze" love khan lolllll

@rogertiger 15 лет назад

great videos... sincerely just one question, can you put a video about center of mass of 2 objects with diferent mass, and know how to calculate it? thanks

@michaelthomas2769 10 лет назад

how do you know how to difference from clockwise from anticlockwise ?

@jasonmyles696 10 лет назад

the arrows

@alexchristie7497 10 лет назад

The direction of the arrow shows the direction of the force. so imagine you hold the pivot point still, then apply the force and look at which way the bar would spin.

@mayateola4732 3 года назад

Hahaha, that sneeze woke me from napping peacefully

@alexhewitt6166 3 года назад

jesus christ that sneeze hurt

@ishaqcasimdeen9073 6 лет назад

Made it worse by wearing earphones at full volume

@camerongray7767 6 лет назад

2018 anyone?

@noor37130 12 лет назад

thank you - for this revision I use to find moments very difficult to come across you don't know how many people you are helping by providing this video - keep providing more...

@camerongray7767 6 лет назад

Thanks that was quite helpful for me

@gabitron420 6 лет назад

when he sneezed i swear my heart left my body dsjsjs

@HotPepperLala 15 лет назад

Taking an online course atm, it was so confusing even though it had better pictures than you have. 5/5

@anava84 16 лет назад

gesundheit

@justinsankar1164 5 лет назад

A 10 year old comment. Its like visiting an ancient site

@firasfreja4560 11 лет назад

Khan, where ever I go , where ever I find people suffering with their courses.. I always refer to you as the best source man.. Seriously, What you are doing and if you develop more and more in your knowledge, I can trust you on getting A's in my courses. Specially those engineering ones.