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

[@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.

[@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!

[@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.

[@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

[@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

[@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..." ;)

[@iieeKatey]

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

[@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

[@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.

[@Ciura_]

14 years ago 😳 Im assuming high school

[@jakey4988]

Yeah sophomores juniors and seniors that’s who’s in my class

[@lucasbassuk3796]

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

[@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..

[@Hoekage01]

Wow 11 years ago

[@happybro2802]

Over a decade

[@edgroves3672]

skip forward a few seconds if it isnt loading

[@truthwelltold5]

Who doesn't understand physics like me?

[@sohammajumder7837]

Not me!!!

[@gilsousa7401]

Imagine not understanding physics, must be sad

[@abhishekbhattacharjee4639]

you have come a long way sal

[@ViizVenomZz]

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

[@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!

[@laimfz]

Dang you commented this back in 2009

[@MulleDK19]

@@laimfz 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?

[@hanashah1]

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

[@muhammadhaziqhafizuddin5411]

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

[@preetisakshimahbubani5933]

Mini mistake ig, it should be -ve

[@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 :)

[@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.

[@pinksugarlylove]

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

[@selvendrans1131]

Ok

[@dbrothers6329]

its crazy that this video is older than I am

[@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

[@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?

[@C3Daddy0]

KHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAN!!!!!!!!

[@Celicaw8]

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

[@Julie59105]

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

[@LaserMonkey]

10 meters?! Now thats one big spring!

[@RanveerSingh-sv9co]

Bigger than your c ...

[@g3mint446]

Video won't load...

[@spoonfullofsalt8889]

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

[@MattSiegel]

20 metres? that is a lonnnnng spring

[@goatedpenaldofan7485]

Ikr

[@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.

[@stevensosa5995]

Thank you!

[@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

[@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.

[@Deaddev1l99]

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

[@hey-go4dg]

helped me alot thanku so much

[@namratachauhan6386]

thanks Mr. Khan.

[@NPowah]

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

[@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."

[@equaygaming229]

Getting this on my test ;)

[@SupremeCoalition]

thank you! very useful.

[@hazemalsoweed3729]

Thanks khan academy

[@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...;)

[@sidneyreed1031]

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

[@kylebtw3625]

Thank you

[@uniqua2621]

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

[@m1h2al3]

he's really good at explaining, but he spends tooooo much time drawing and wasting time over silly things

[@dr.najeebullahqadir5858]

play the video at 1.25 or 1.5 times the original speed

[@chainsamguacamole6647]

Since this is an earlier video, maybe he wasn't as used to the software as he is now. Now he doesn't waste as much time with these things. At least this is what I think.

[@diegoguatemala1520]

clearly you were not paying attention my friend hahahahahaha who cares when you need to learn?

[@charmendro]

I think it’s good for people who need more time to process.

[@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.

[@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)

[@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?

[@XxAlessiaxX1]

i can always rely on you

[@BengBengCat]

Thanks so much

[@charmendro]

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

[@t-h787]

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

[@Zainabali.2000]

What does Hooke's law depend on?

[@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

[@pithikoulis]

thanks loads :D

[@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?

[@bagyaaluthge3111]

Ty

[@alexiskruljac9201]

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

[@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

[@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.

[@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 ??

[@megashani91]

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

[@MattyHild]

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

[@volintine]

thnx sal

[@benjaminneufeld6137]

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

[@dravidr007]

can u go into finite element analysis

[@wasihhassan403]

can someone please explain what k is in hookes law?

[@deyrudra]

k is a constant that is, its a number

[@zujajamohyudin7129]

how do we join your academy?

[@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 :)

[@hey-go4dg]

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

[@sidvanleeuwen6681]

X is 847375

[@SpankAgoose]

Can you make video about elasticity please?

[@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

[@paypuhboy2863]

love you KHAN

[@megashani91]

yes i think he created another video to correct this

[@khiemluong-c6f]

so F is not the applied force?

[@seonghwa8902]

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

[@RadialEffects]

the force is strong in this one

[@Bennethp]

I wish they would redevelop these videos

[@edsradio5817]

This man is god

[@NomanKhan-lo4tc]

Good

[@KashmalaNawab]

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

[@lawlgirl97]

he doesn't need to prepare he's amazing

[@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

[@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??

[@UNBASHDub]

Why isn't the video loading?

[@khoip4937]

try changing the speed of the video to 1.25 or 1.5 or just click midway into the vid lol. Worked for me.

[@skyfaze]

hold on a second so is the last question right or is gregme right

[@slownightsolongg]

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

[@momentlikethat]

yeah I figured that out later

[@Stickbabiga]

Why do ALL educational videos teach people more in 10 minutes than their teachers do in 10 days?

[@swetashaw5710]

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

[@denzeltracy]

what exactly is K?

[@KingBarney]

Spring Constant. Kinda like the strength of the spring. Every spring is different, some harder to pull/push than others. The spring constant just represents that.

[@vi7461]

King Barney hello king barney, but in what is K measured? And how do I get the spring constant? It'd be great if you could help

[@KingBarney]

Levi Nordmann K's SI unit is Newton's per Meter (N/m) or Kilograms per Second squared (Kg/s^2). You can find the spring constant from the formula F=-kX, where F is the force required to extend or compress the spring, k is the spring constant, and X is the distance the spring is stretched or compressed. Really I just googled it all. If you need help Google can always provide quick and specific answers. Hope I helped!

[@essamcream6194]

Its fine now

[@MyVitros]

To the left to the left

[@y.alenezi5747]

Useful video but not the one looking for. Like