Intro to springs and Hooke's law | Work and energy | Physics | Khan Academy

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Introduction to Hooke's Law. 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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[@JohnHorak]

I think the people who go out of their way to put videos up on youtube for free generally have an enthusiasm that not all teachers have (some anyway)

[@ryanechelberger7035]

He makes money off the video though

[@butimohammed3264]

@@ryanechelberger7035 it is still generous of him, how much he could be making from online paid courses isnt even close to what he makes from youtube.

[@Peter_1986]

@@ryanechelberger7035 Yes, but his channel was created because he started out with helping people for free, and he insists that people should be able to use it for free without being forced to pay for it.

[@virajyadav3826]

its a fundraiser @@ryanechelberger7035

[@Peter_1986]

I believe the typical flaw of many physics teachers is that they don't really explain things in-depth, they just shove formulas into your face and tell you to calculate something. Anyone can put numbers into formulas, the real challenge in physics is to actually understand what's going on and WHY the formulas look the way they do. Khan is very good at explaining those kinds of things, and it gives you a much better intuition.

[@LockIn367]

so true

[@ZnNlove]

Good ol' days of 240p Khan Academy

[@tokyo7671]

lmao

[@Anush_Sivakumar]

lmao 2021 now XD

[@falll7631]

:D

[@alishakhan7076]

X)

[@WarriorBane]

Im late to the party, ap physics 1 here trying to get a 5

[@asparwhite86]

You totally kick my professor's ass.

[@jeff30458]

mine too, my online class is a joke.

[@iieeKatey]

Why wasn't the restorative force in the last example -2N instead of 2N since it was acting to the left?

[@mannyStern]

Sal, I am a retired former physicist trying to relearn what I used to know. Can you please tell me what grade level physics you are targeting? Since I have not looked or thought of physics for 40 years, I am having a ball with your videos.

[@RanveerSingh-sv9co]

Most likely this Stern dude is dead by now.

[@cg2203]

click the little settings cog and above quality change the speed to 1.5. exams are too soooon

[@notveryrea1]

Saaaameee literally tmr

[@brawlboi2946]

Lol, I have my SAT Subject Tests tomorrow (2nd November)

[@brawlboi2946]

@Jesus bruh, it's been so long

[@Icareaboutyourapple]

wow when he says that he has run out of time bc the video was posted in 2008 and YT videos could only be uploaded at 10 minutes max. Oh how the days have changed.

[@lucasbassuk3796]

This video is older than me, yet here I am using it

[@AT-ki3px]

When I am in class, I'm like, "GOD WHAT CAN'T THIS PHYSICS CLASS BE SHORTER..." When I am watching this video, I'm like, "GOD WHY CANT THIS VIDEO BE LONGER..." ;)

[@edgroves3672]

skip forward a few seconds if it isnt loading

[@AnastasiaDinda]

Watching your videos always makes me envy the kind of education developed countries get, where i'm from physics might as well be math with different units ..

[@yesyes4005]

keep blaming your environment. Fucking loser .

[@iMusikkForeva]

+YES! Yes! How rude and arrogant! She's voicing her opinion, there's no need to judge her. Moreover, you know nothing about where's she's from or the struggles she has, so don't try and act like it's nothing. We all have problems in life, and yes...the environemnt does matter. Some students simply don't have the same opportunities and facilities as others, and this is an universal fact. Furthermore, an overwhelming percent of the time it DOES create an impact on the future of the students. So focus on your own life, and keep your negative attitude outside of others'.

[@BLURtm]

I completely agree with you iMusikkForeva.

[@yesyes4005]

You have a notification

[@Mitchelloni95]

Thank you so much! I was feeling a little shaky about a few things for my Physics exam that I forgot to ask my teacher, and these videos have really cleared things up!

[@ViizVenomZz]

go to settings put the graphics to 240p and it will surely work :}

[@captainspiwtf]

Hey Sal, I remember hearing you say you can code too. You are a brilliant teacher, could you do some video tutorials on C++ or some other programming language? Its a lot to ask but it'd be amazing... thanks anyway man.

[@spicyshizz2850]

Wow 12 years ago

[@jovany4163]

Wow 1 year ago

[@poppyqueen7894]

@@jovany4163 wow 8 days ago

[@lenny91]

@@poppyqueen7894 wow 3 days ago

[@poppyqueen7894]

@@lenny91 wow 2 minutes ago

[@ull893]

All your videos there is one thing common...at some point in the explanation you hit the bulls eye of explaining the logic behind the topic..that makes it interesting rather than blindly bye hearting the formulas...Thank you very much..

[@Kakashi-jc8hc]

Wow 11 years ago

[@happybro2802]

Over a decade

[@muhammadhaziqhafizuddin5411]

In the last example, why the sign of restoring force is positive?

[@preetisakshimahbubani5933]

Mini mistake ig, it should be -ve

[@MattSiegel]

20 metres? that is a lonnnnng spring

[@goatedpenaldofan7485]

Ikr

[@hanashah1]

Thanks for the great expanation! May the FORCE be with you :)

[@abhishekbhattacharjee4639]

you have come a long way sal

[@doreenstanley1507]

Restorative force for the last example is NEGATIVE 2; I think Khan put positive 2 by mistake

[@yourpapidario]

youre right

[@KingBarney]

Yeah, noticed that, too. I love when I understand well enough in the beginning to recognize a mistake later on in the video. Makes me feel a bit confused but also let's me know I understand well enough to even recognize mistakes.

[@simontalamantes3610]

Lol king Barney? Not on skate or mortal combat videos? Get outta here

[@KingBarney]

Simon Talamantes Hahaha. Got a final exam in 4 hours. xD

[@simontalamantes3610]

How'd ya do Barney?

[@yasiru221]

video doesnt load for me, tried it on both youtube and khanacademy site, doesnt work

[@nathanc9110]

try it in 240p, i was having the same problem, but 240p worked for me.

[@quantum_fluff1344]

Nathan Cameron thx mate really needed that :)

[@robertchristian4248]

11 years later and we are all still here

[@layakrishnan5999]

I know right

[@mastersanada]

Cause Physics can't explain jackshit. (Well, in my case my teacher teaches so slow and so incoherently that everyone falls asleep and no one learns anything except those people who already know all of AP Physics)

[@sakirhossain]

When u pulled the spring 2N to the right the Resistance force is -2N. and since you move 1 meter, F= - K X -2N= -k * 1m k= 2 not -2

[@SupremeCoalition]

thank you! very useful.

[@Celicaw8]

-5N to the left direction (as drawn) means 5N to the right

[@stevensosa5995]

Thank you!

[@hey-go4dg]

helped me alot thanku so much

[@uniqua2621]

I was only 3 when this was released and now Its finally my turn.

[@MulleDK19]

"If you stretch something too much, it never really goes back to where it was before"... I lol'ed xD Awesome videos, btw. Keep going!

[@metallicphoenix791]

Dang you commented this back in 2009

[@MulleDK19]

@@metallicphoenix791 I guess I did.

[@angelisvegan5826]

@@MulleDK19 you must be old now.. 12 long years

[@objectoriented3049]

How are you doing now?

[@duk2k]

14 years man. Are you still alive?

[@sidneyreed1031]

Surely the signs for the last question would have to change??

[@truthwelltold5]

Who doesn't understand physics like me?

[@sohammajumder7837]

Not me!!!

[@gilsousa7401]

Imagine not understanding physics, must be sad

[@g3mint446]

Video won't load...

[@pinksugarlylove]

Thank you so much(: Love the video, it really helped me alot A LOT(: May God Bless YOU(:

[@selvendrans1131]

Ok

[@charmendro]

Wouldn’t F=2x in the last example ? Since u had k = -2 therefore -(-2)x would be the function

[@equaygaming229]

Hooke's law states that the extension of a spring is directly proportionate to the force applied.

[@hamzaanwar92]

within the limit of proprtionality

[@cjitfc6731]

What

[@namratachauhan6386]

thanks Mr. Khan.

[@equaygaming229]

Getting this on my test ;)

[@C3Daddy0]

KHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAN!!!!!!!!

[@kylebtw3625]

Thank you

[@LaserMonkey]

10 meters?! Now thats one big spring!

[@RanveerSingh-sv9co]

Bigger than your c ...

[@BengBengCat]

Thanks so much

[@Julie59105]

These people actually know how to teach, verses others that attempt to teach.

[@Breaker5764]

@NPowah But spring force should be in the opposite direction...I thiink Sal is wrong, because the APPLIED force he used was (+2 N) and the restorative force (spring force) he put down was (+2 N). He's solving for K, so conceptually, he should put down the correct F to get the correct K. If he was solving for F, then yea, the (-) would factor itself in to get the spring force (F) in the opposite direction and all you would need to worry about is getting the correct sign for distance.

[@dbrothers6329]

its crazy that this video is older than I am

[@bagyaaluthge3111]

Ty

[@bhuvi441]

So even if I move a car by distance x or if I move a pin by the same distance X then the force applied by me is the same for both cases ??

[@t-h787]

the quality of the video looks like it was recorded using a calculator

[@benjaminneufeld6137]

how does the 1/2 part come into play in the restoring force =-kx formula

[@BenLewisE]

I can tell you as a student that often students don't want to be in lessons or don't care about what their teacher is saying, but if a student stays around long enough to watch a video then they definitely care enough about the topic or like way it's taught and it's a convenient time for them. Hence students always find educational videos more convenient and hence better.

[@Deaddev1l99]

You're right. K should be 2 in the last equation.

[@farzanamariyam4665]

If I take positive X to right and negative to left since force is also a vector quantity shouldn't it b negative to left as well?

[@hazemalsoweed3729]

Thanks khan academy

[@spoonfullofsalt8889]

I fell asleep in my physics class explaining springs and Hookes Law, this video is a total lifesaver

[@XxAlessiaxX1]

i can always rely on you

[@pithikoulis]

thanks loads :D

[@maquistom5837]

You would have to watch Khan for a month or so without a break in order to watch all their videos. I just calculated it assuming the videos average 10 min in length. Better start somewhere...;)

[@xenomann442]

Because lots of teachers don't fully understand what they are teaching. They know how to get the right answer, in terms of using the formulas correctly, but I bet you they couldn't break down what that formula is actually doing... They don't understand WHY the formula works essentially. Don't get me wrong there a lots of awesome teachers (from my experience at least), but there are also too many that simply teach the curriculum, without an in-depth understanding of what they teach.

[@pandemade3875]

isnt it supposed to be f=-(-2)x for the 2nd question? anyone?

[@iMusikkForeva]

Yes, that's exactly what I was thinking!

[@supergolfer8337]

yes

[@hagerebraheem1295]

he assumed that (k) is positive for all purposes and if k is negative number besides the negative sign and x for example in the positive direction the conservation force would be in the same direction and the same if x in the negative direction which is wrong

[@alexiskruljac9201]

At the end of the video, why isnt the restorative force -2 since its acting in the opposite direction?

[@hey-go4dg]

in the last question isn't restorative force -2 Newton cause it's acting towards the left?

[@sidvanleeuwen6681]

X is 847375

[@KashmalaNawab]

Oh my god when this video was uploaded I was just 1 month old

[@khiemluong4591]

so F is not the applied force?

[@user-ez1sz8yb7f]

What does Hooke's law depend on?

[@MattyHild]

Would gravity have the same effect on a spring that is attached to a roof/ceiling?

[@volintine]

thnx sal

[@megashani91]

I bet he has a higher pass rate than your "professional and organized" teacher who prepares for classes

[@surroundsound5000]

"Hooke's law states that the force produced by a compressed spring is dependent on the amount by which the spring is compressed. If a spring compressed by 1 cm requires a force of 1 newton, then compressing the same spring by 2cm will require 2 newtons of force."

[@QuicklimeProductions]

newton must feel like such a badass, forget a building or even a species or a star, he has a force of nature named after him.

[@dravidr007]

can u go into finite element analysis

[@SpankAgoose]

Can you make video about elasticity please?

[@NPowah]

@ mygremg Sal is actually correct, since he is discussing the Force of the spring, which is F = -kx

[@fwesterbergh]

But if the spring is at rest the restoring force must be zero?

[@MattSiegel]

The spring is only at rest because you're still pushing on it. If you stopped pushing it would spring back at you. *That's* the restorative force :)

[@badguyfromstarwars]

Shouldn't the value of K in the last example be positive due to the fact that the force isn't put to compress? In that way it's negative from the beginning, -2N to counteract the positive force of 2N?

[@Bennethp]

I wish they would redevelop these videos

[@seonghwa8902]

may i asked why the formula is F= -kx ? because in my textbook and reference books it said F = kx

[@NomanKhan-lo4tc]

Good

[@slickwillie3376]

So, to make a three inch long shock absorber (.076 meters) for a cane, that will support a body weight of 220 pounds (979 N), then F = 979 N = .076 × k k = 979N / .076 = 12,882 If I am willing to double the length of the shock absorber, then k = 6,441, which might be cheaper.

[@paypuhboy2863]

love you KHAN

[@edsradio5817]

This man is god

[@megashani91]

yes i think he created another video to correct this

[@wasihhassan403]

can someone please explain what k is in hookes law?

[@TheLeafInTheHidden]

k is a constant that is, its a number

[@jerrycornelius6335]

OK--What is the name for a spring that is used in click clack device and also a clutch plate spring as the same. You apply force and when you reach over halfway the spring then continues. On a new Clutch you will feel the resistance and the it pulls itself in.??? come on ? I cannot remember the name??

[@nicholaslombardo2775]

He used the force applied force instead of the restorative force so k should be 2 instead of -2. He should have known something was wrong as soon as k was negative which is impossible

[@VannAleXX]

Wouldn't k in the second equation be 2 and not -2? Since he's applying the force in the positive direction, the restorative force would be negative, so -2=k*1, so k=-2? Isn't that what he did in the first example?

[@cjitfc6731]

No idea mate

[@momentlikethat]

yeah I figured that out later

[@RadialEffects]

the force is strong in this one

[@slownightsolongg]

@LOLzxcvb the spring constant, its different for different types of springs and shows how stiff a spring is.

[@essamcream6194]

Its fine now

[@anishbachan4763]

ya

[@swetashaw5710]

Cannot understand simple harmonic motion of horizontal elastic string and mass system. Mind it it's string not spring

[@user-qy1de7mt6c]

Me to

[@MadinaAfg94]

00.26. That's what he said

[@MyVitros]

To the left to the left

[@anishbachan4763]

ikr

[@Meckro]

240p This is HD KZbin quality right here!

[@925LY]

made in 2008

[@dhirajkhanal5364]

Wow

[@zujajamohyudin7129]

how do we join your academy?

[@y.alenezi5747]

Useful video but not the one looking for. Like

[@bananian]

Is there a Springe's law for hook physics?

[@andrewm2786]

this joke went unappreciated for 9 years...but I'm here for you. I laughed.

[@bananian]

@@andrewm2786 I've been waiting for this moment for 9 years :_)

[@haroonk.9706]

@@bananian you must be long done school at this point

[@RanveerSingh-sv9co]

@@haroonk.9706 yea, let's see