Introduction to tension | Forces and Newton's laws of motion | Physics | Khan Academy

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An introduction to tension. Solving for the tension(s) in a set of wires when a weight is hanging from them. 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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[@deiu9999]

Wow, wow, I never knew all these concepts are so logical and I guess that`s the problem with most of nowadays teachers, they just fill the table wih formulas without telling us where it all came from... But you sir, you mannage to do this and I must say: "Thank you a lot, sir!" :)

[@manasmarathe9579]

There is no formula for this

[@josephjithu8484]

If Einstein had studied like that he would not be Einstein bud, he would be another brick in the wall

[@victorprentice1062]

AP Physics got me like “A student is going to hang himself because of the overwhelming topic that he fails every test and paper in. He is trying to find a rope that can support his weight. The student weighs 50kg. What is the tension of the rope?”

[@libertax9213]

There is no tension because there is no rope.

[@crazykraken55]

400N (100N loss of brain cells)

[@annabeladesousa2692]

The minimum tension that the rope can experience is 490 N,thus the tension will be 490 N upwards.(equilibrium)

[@rubinakausar9559]

Victor Prentice I agree with you

[@snehalkancharlawar315]

Thats actually me rn, im so dead and tired, ugh

[@top10swithtopaza40]

This is 15 years old now, but it's still better than the material I get in school, thank you so much Khan academy

[@awesomealf79]

Heh true

[@suchasrinagam7265]

The fact that i got better notes here than my online class makes me wanna quit school and learn everything here!

[@enderf4515]

umm..... probably a bad idea

[@kingofstuff1732]

@@enderf4515 honestly I agree with them, my teacher is not good at teaching, at this point I'm pretty much doing self-study for ap physics

[@add5955]

I get the concept of tension well, seeing how I get it everyday sitting in a Physics classroom

[@TunaNoCrust305]

For future reference, at 8:50, to solve T1 1/2= 100, you have to get the T alone. So to do that you have to cancel out the 1/2 and the way to do that is to do the opposite of division, because 1/2 you are dividing, if you were multiplying you would divide, so you multiply with the recipricle of 1/2 which is 2. So what you do to one side you do to the other, 2 * 100 = 200. T=200

[@aqualife88]

KCF keep change flip lol

[@nickboldan7833]

Very well explained. Tension can seem like some abstract thing, but it's really just a force, and often students aren't made aware of that until they see real-life examples.

[@YourFriendDevin]

I’m heading over right now to fix that gap in the green line

[@how-toplaygames4987]

its been 10 years, and im still watching this

[@SafeAndEffectiveTheySaid]

What this guy do is a really good job. If you can help someone out, you are a good person. But if you help people all over the world, you are like an angel.

[@protopug_]

wow This comment was written when I was 13

[@SafeAndEffectiveTheySaid]

@@protopug_ times flies. Hope you enjoy your college time as much as I did.

[@protopug_]

@@SafeAndEffectiveTheySaid wow, didn't expect to get such a quick reply and thank you for your wishes

[@ranindunimesh4036]

@@SafeAndEffectiveTheySaid how are you doing now?

[@Ahfjo]

I always wondered does the maximum tension of a rope change depending on the length of the rope? Obviously, the material of the rope has to be the same in both cases, but can longer rope hold more weight than a shorter rope?

[@bhargav7215]

Depends on the force exerted...

[@soumyajoshi176]

2012 Khan academy, here I am in 2021

[@22kuter]

Thanks, this lifted my stress as my teacher didn't explain it very well, and this explains it in such a simple way, thanks

[@XH1tokiriX]

great way to study for mid-terms. Thx!! =]

[@BarbarosZeren]

Wow 12 years ago. I wonder what are you doing right know.

[@XH1tokiriX]

@@BarbarosZeren I don't even know how you found a 12 year old comment!! I'm a police officer now, fell a little short of my scientist goal loool

[@BarbarosZeren]

@@XH1tokiriX I hope you are doing great. I wish you the best.

[@galachoxy]

Ur a great teacher,,,,u make it simple and clear unlike my teacher in physics who just make get a hard time in solving a tension n' frictions,,i like it so much...thanks a lot from timor-lete..

[@Nguyening_music]

Professor, can you do that WHOLE problem again for me? Professor: HELLLLLL TO THE NO! youtube: sure click replay :)

[@ankuraks3919]

9 year old comment 😨😨

[@cdgod616]

@@ankuraks3919 10 now lol

[@tricklander]

​@@ankuraks39193 year old reply😭

[@kundai5265]

Thank you for this! made perfect sense for once

[@AtlasJS]

@grandprix1110 i realized why i was getting the question wrong... the calculator wasn't in degrees, so each time i would use sine and cosine the answer would be wrong because my calculator wasn't on the degrees setting... FML

[@DeMonYitOoO]

Thank YOU!!! SO MUCH!! YOU HELPED ME ALOT I HAVE A TEST ON WEDNESDAY THANYOU SO MUCH!! ILOVEYOU!

[@Dan4157]

but good sir, that makes too much damn sense!

[@Master1906]

You are completely correct. As sin(angle) approaches 0, the number becomes infinitely small, in other worlds, [100N]/[Very small number ] = Extremely large number. So at 0 degrees, in order to keep the string taut under the weight, it will require infinite tension no matter how small the weight is. Think about this. Get a string. Make it horizontal and straight. It will NEVER be perfectly straight and taut due to gravity pulling the middle section down, no matter how hard you tense it.

[@fefafe334]

his favorite word is "intuitive" .. lolx!

[@xxminaxcoladaxx]

Brilliant....really clear and helpful thank you. I have a forces test on Monday and you've really helped to refresh my memory!

[@CEMAGC]

did you get an A+?

[@boniquer931]

@@CEMAGC bro he passed the whole thing from 11 yrs lmao

[@pirate1406]

Could you make a video with a problem that has a string with mass? Thanks

[@QuicklimeProductions]

I think the force is distributed throughout the whole rope so it could, like how a larger pot of water take more heat to boil because the thermal energy is distributed through more water, a larger rope has more area to distribute the force so it could handle greater forces before breaking. Idk for sure though...

[@hppaviliona1700la]

Please make a video of this but with an angle in the T2! Your videos help me a lot, thanks!

[@ua24986]

he always says, "I'll see you in the next video" but actually only talk to us, I wish he showed his face...I would like to see this professor!

[@ajaysvlog9958]

15 yrs nice

[@jfmarque]

Could you please explain an example using an angle as unknown?

[@Abril-ge8uq]

I'm watching this and my midterm exam is tomorrow

[@ibrahimmahmoud7714]

Same

[@alizayrehan4849]

Same

[@iwannacommitjisatsu5858]

Same, I'm having a midlife crisis rn. I'm gonna fail Sci ngl

[@SSTube80]

you are the man for doing this, thank you!

[@pushpanarayanpur]

Thank you so much. Excellent explanation!

[@lazaruz01]

Haha! SOH CAH TOA in blood red. Like the blood in my nose when I couldn't get this topic when I was in high school

[@bobross3356]

Jera Angeles lol

[@ankejkumar1120]

Family tension

[@zahidahmadzai8023]

Ur forehead is bigger than my entire future

[@mr.knowitall5019]

Spaced repetition

[@carlybutler9190]

Thankyou!!! I have a test tomorrow and this is perfectt!!

[@7clouds567]

Hey there... this seems 9 year old... What are you doing now?

[@Ashrafustad08]

Yea same question

[@seavech]

thnx a lot!!! now i am ready for the test that i have in an hour!!! THNX A LOT

[@phanidruva]

Since the body is stationary, the sum of all forces is equal to zero? Is it so?

[@aragonification]

Since the body isn't accelerating*, I think.

[@aragonification]

Since the body isn't accelerating*, I think.

[@lazaruz01]

It's the idea...Equilibrium should mean that the object is not accelerating and to the that all the forces must be equal to zero either to keep the object stationary or moving in a constant motion.

[@sanaakhan6273]

yes, it is in equilibrium

[@muhammadjawadaslam9020]

Hmmm... I think if you do not consider the rotation velcoity of earth then yeah, but since the direction of rotation is constantly changing then velcoity of earth is constantly changing, therefore it exerts its effect onto us, but since the system and us observing it have the same velcoity at every point on the Earth s surface, we say it's in equilibrium, as we consider that velocity as constant.

[@priyanshusobti9935]

thnx sir I was never able to solve complicated tension problems befor watching this👍

[@ajaysvlog9958]

Its been 6years boy

[@cubesolver]

I like how the 30 degree angle is larger than the 60 degree angle

[@janahsabriyamacapundag3448]

WOW I LOVE THIS

[@olivermathiasen3594]

Very well explained. Didnt understand the last part. But ill rewatch after some sleep. Hopefully it will get in then.

[@Nutterbutterz95]

"Soh Coh Toa, in blood red". Was that even necessary? Lol. I love your videos. Honestly, you're an amazing teacher.

[@yiumyoumsan6997]

Hi

[@uralegend123]

Finally, this is the first time I've seen trigonometry in application

[@TheKmanOfSmash]

So with a 100N weight and the angle T1 makes being 30 degrees, the tension in the T1 string is 200N (100/(sin30) = 100N/(1/2) = (2)(100N) = 200N). I understand that. Now, this happens to be double the weight of the original weight (100N). Does this mean that as the angles T1 makes approaches 0 degrees (horizontal), the tension in the T1 string approaches infinity? If so or not, why? And if so, why is the tension in T2 not infinity by this logic?

[@legoindianajones1000]

So how do you involve calc in physics? Integration? Derivs?

[@seifdeiab]

Why we did not use sin60*?

[@AimlessZealot]

Physics is full of calc: Uniform Force = (mass)x(acceleration), and (acceleration) = (Rate of change of velocity)... Anyone taking basic calc (derivatives) recognizes "Rate of change" meaning "Derivative of". Momentum = (mass)(velocity) and Kinetic Energy = (1/2)(mass)(velocity)^2. Users of integral calc recognize that w/ constant mass (both equations are), kinetic energy=integral of momentum. Physics is full of calc, but if you don't know calc you can memorize and muddle through.

[@thedepthofmymind]

Such a classic we have here.

[@gerrenx7]

Bless you sir

[@pjtheman1]

the reason he used trig is to help apply the concept of conceptual thinking and help you understand whats going on and why the things work- the pythagorean theorem would be able to do that - but that would get the right answer- but good thinking bkisme

[@USMChiLD]

Thanks Sal.

[@arjungathwala8217]

Great video! Sal is the real man 🐉

[@asteroides8204]

can i just say, I LOVE YOU. I WISH YOU WERE MY TEACHER

[@meatmissile8229]

This video made me understand this concept a lot better. I do have a question though. Sal used a triangle to the right of the T_1y vector. Couldn't he have used the same triangle on the other side of the vector where the side parallel to the y component would've been straight up from the weight? The angle is the same as he stated, and the use of sin is still the same because the y component is still the opposite side from the angle.

[@sunritroykarmakar4406]

Meat Missile yes but the second part of the question would have become more complicated. it is the same really

[@funkyboy_22]

Audio's pretty bad. In middle volume, I can hardly hear anything.

[@trailertrashtactics]

anybody else notice that the intro to this video compared to the ending of the last sounded like Sal was recording in his closet trying not to wake up his wife and kid XD. This guy is seriously incredible though.

[@shamimjaved8714]

its very helpfull for students

[@abhishekutkarsh]

you are great !!!!

[@IQ-rl2wx]

Such important concepts

[@Hunnymuffin321]

@rnichols16 that gets confusing for me too, but if you we're to multiply 100 by (1/2) it would be 50, but you were dividing in this case. 100/(1/2) is the same as 100 times the reciprocal of (1/2) which is 2.

[@fozanshaque6094]

awesome explaination

[@AtlasJS]

@sk8rlt Thats where the problem is i understand the concept yet i don't know what is going on that im getting wrong. I love math and one of the reasons is that i've realized that in math if i get an answer wrong i can just retrace my steps and find that one small addition error or maybe a negative sign i forgot to place at some point or another, but in physics that's not the case. I can't seem to find any errors in what i'm doing and therers so many steps its just overwhelming.

[@sc00biedoo]

this is fantastic!

[@niceguy4801]

Thankyou sir

[@Shivastorm88]

You, sir, are a God amongst MEN!

[@ibraheemmonks8866]

Which pixel is the string?

[@JulianGarcia-um5ku]

isnt force of gravity equal to mass times 9.8 so the fg would be 980N in his case and not 100

[@bartkelly4382]

This is true if he drew the weight in and labeled its kilograms but he instantly wrote it in Newtons, so you could derive the mass to be about 10.20kg in this example. If he had said it was 100 kg then it would be 980 Newtons as you said

[@rjbrianclavel20]

False. 100N is already a value whichs is equal to (Mass)(Gravity) .

[@prav8141]

mass is 10 kg. fg = 9.8 = 10 * 9.8 = 98N not 980N. 98N and 100N are close enough, as he used 10m/s^2 as fg than 9.8m/s^2

[@sunritroykarmakar4406]

approximate

[@Jeromebefit]

I thought it was pretty good. Do another problem where something is hanging from one string and then it has a rope attached to the left 15 degree below the horizontal and then a rope from the right with a 25 degree angle. The tension on the rope to the left is 500N. Whats the tension on the 25 degree rope? Something like that.

[@yc9928]

Thx teacher khan

[@Yaj-kk4is]

nice

[@NishieFernandez]

it's dat easy? ;) thx man

[@megaelliott]

He does that to try to give people intuition.

[@arpangoswami2333]

you are good

[@fleshcookie]

Sal has his Rico Suave voice on in this video

[@serenavue4254]

How did you know what equation to use to find the T1x component?

[@khalidfaiz8735]

bro your videos are the best

[@BrentonaBike]

Can you do a video in regards to vertical cables with pretension and horizontal forces?

[@A591m]

this video made me realize this was really the easiest thing ever but why did it seem like such a messy and horrible thing to learn during class.... lol

[@ammad____4651]

A string is stretched by two equal and opposite forces 10N each. The tension in the string is.....?

[@nirmitbatavia8192]

Ammad King 0/infinity

[@Justshorts-j2c]

Thank you sir 👍👌

[@and1fer]

well those are some thick fuggin lines

[@Nutterbutterz95]

It is. What made you think it wasn't?

[@mairakapoor9423]

Shouldnt the force of gravity be 9.8 m/s? Instead of 100 N?

[@youknowwhatimtalkingabout]

6:40 'SOH CAH TOA in blood red'

[@RandomIndian001]

soh cah toa.!!!!!!!!!!!!!!!!!!!!!!nice!!!!!!

[@baretings1]

would you call the tension the reaction force of the weight of the block? or is it a seperate force and will have its own reaction force?

[@khabibconor1566]

no its reaction force i hope i was helpful

[@griftorifto2]

@Deserfox1972 Because 100 newtons is its weight, this includes gravity. Newtowns/weight = mass x gravity

[@ChizzMikNik]

So if the T1 string is doing all the up lifting of the 100N block, then why isn't the tension 100N? :S :S

[@emmafrankly]

So does T1 include the blue string directly above the object?

[@Miodoll]

wait, sal i'm confused on the second part of the problem, the t2 cosine, for some reason when i did it I got t2 = 200 root 3 over 3...... how did you get your answer? btw i love you videos, you get me A's in all my penn state courses. You rock.

[@khabibconor1566]

yh he is amazing

[@Papaabe]

when the string breaks will the particle move a distance before hitting the ground, please I need a quick answer

[@thewilliamjrful]

why would you need a second explanation when it's getting explained by Khanacademy.

[@SgxNaaBoy]

@desertfox1792 It has already been multiplied by gravity, thats why its in newtons and not in kg or any other unit of mass.

[@benihana360]

thank you so much!!!!!

[@nidaaa7714]

many thankkkkss

[@myworld-si8zk]

good

[@muhammadadel191]

woooondeeeerfuuul >> Bless you!

[@crzyaznpistonsfan]

He sounded incredibly ominous in the beginning of the video. "I will now introduce you to the concept of tension...muahahahaha."

[@funkyboy_22]

It's so confusing

[@nirmitbatavia8192]

RadiantBlue3 go to hell

[@dhairyasalot3478]

Nirmit Batavia why such hate?

[@nirmitbatavia8192]

dhairya salot can u do your own work instead of poking ur *** in every matter

[@dhairyasalot3478]

Nirmit Batavia thanks for showing me that a person like you cannot reply politely

[@nirmitbatavia8192]

dhairya salot of course because then people like u will poke up everywhere

[@FastKid26]

YES WE KHAN

[@michaelpalomino6239]

how is that angle 30 degree's? I always thought that the angle closest to the 90 degree angle is 60 degrees and the angle farthest makes the 30 degree angle.

[@sunritroykarmakar4406]

Michael Palomino no.

[@acmctheworld2107]

Man I love paying thousands to only have to go to youtube to actually learn something in a understandable way.