Newton's Laws: Crash Course Physics #5

[@crashcourse]

We made quiz questions to help you review the content in this episode! Find them on the free Crash Course App! Download it here for Apple Devices: apple.co/3d4eyZo Download it here for Android Devices: bit.ly/3TW06aP

[@randallpcrittenden]

My favorite explanation of Newtons laws comes from my high school Physics teacher: 1.) Stuff is hard to shake 2.) More stuff is harder to shake 3.) Stuff pushes back

[@Bloxicorn]

My science teacher's explanation,(or at least I think she said this I was kinda asleep): 1.) IYUGVLJGY{YGYV:Gljewdnjqv 2.) prgwd9f3edwgytyftewdhhhhhhhhhhhhhhhhhhhhhhhgy 3.) Get out of my friggin classroom

[@daveforfav7650]

@@Bloxicorn What ur teacher was probably saying 1 (explain things ) 2 sees u sleeping says get up Mr or u getting out of my classroom 3 kicks u out

[@Bloxicorn]

I'm a better man 5 months later. I do not sleep. At all.

[@jerryscanas]

@@Bloxicorn My science teachers explaination 1.) Your 2.) Mom 3.) Gay

[@swarnalatha5242]

You are high school and you are learning this now?

[@kamalbhamra3146]

A student in bed will remain in bed until acted upon by a large enough panic : The lesser known Newton's 4th Law.

[@liawxinyan]

HAHAHA a sense of urgency.

[@tanyay1073]

+LelWut Urgency or a nagging mom 😂

[@ShamWerks]

+Kamal Bhamra Happy the Student he who like river, can follow his course without leaving his bed.

[@adrianbornabasic7499]

+Kamal Bhamra lmao

[@ASOUE]

+Kamal Bhamra I always remind my professors about that one when they mention Newton's laws.

[@undergroundskeptic2916]

"Now the normal force isn't like most other forces. It's special." so much for normal.

[@billy-mild]

+

[@tfos993]

Amy Samuels Poor normal force always being ignored at surface..

[@frankdayton731]

Normaw*

[@shaleygerman6001]

"I'm not like other forces"

[@Bobelponge123]

ShaleyGerman "I'm... Normal"

[@JayTohab]

Newton's Laws of Motion: 0:53 - First Law (Inertia): "An object in motion will remain in motion, and an object at rest will remain at rest, unless acted upon by a force." 1:37 - Second Law (Fn = ma): "Net force is equal to mass times acceleration." 3:40 - Third Law (Equilibrium): "For every action, there is an equal but opposite reaction." 4:52 - Further explanation on Normal Force and Tension Force

[@VikaS-uk7xg]

When your physics final is tomorrow and you tryna learn everything the night before... 😂😂😂

[@sophiavega8514]

Or the morning of lol

[@alanah7300]

Thats me bro tbh

[@hamidalrawi2204]

so how did you do? I hope good !!

[@lynnegharib2548]

Vika S omg thats me rn wth

[@mikayla7006]

Vika S sameeee!!!

[@sniperammow4865]

Newton slaps top of car. Car slaps newton back. Equal and opposite force!

[@michelecole4493]

It would also be an unbalanced force

[@sniperammow4865]

Isabella Fetter wait what? Ohh I remember!

[@ddharsh2548]

I don't think there were cars back then

[@FlyLeah]

If there wasnt a opposite force the hand would go trough the car:) The pain and sudden stop is feeling of the opposite force

[@orie315]

@@ddharsh2548 it was a joke. You just got wooooshed

[@joshbreesus2781]

Stop scrolling through the comments and actually listen to the dang video

[@FenrirWolfe1]

I actually know all this stuff... Why am I here again? KZbin, everybody. KZbin....

[@jogama1059]

lol right? this is all common sense if you like legos.

[@mariyanfernanado9660]

hiiii darling

[@0egg0]

Josh G no.

[@maximilianmaximus3639]

caught me

[@bryanu1737]

"There will be no Christmas without physics" *Reindeer flies with sleigh* (Defies physics)

[@shivannapv4262]

The the universe cannot be as we know it without Physics.

[@EugeneKhutoryansky]

The arrangement of the Rubik's Cube in this episode is still exactly identical to its arrangement from last episode. Unfortunately, this means that no one is even trying to work on it in between episodes. This just isn't right. Whenever you see an unsolved Rubik's Cube sitting around, fixing it should always be a top priority.

[@Raylock]

it's not that hard to solve a Rubik's cube and solvers generally like the unsolved version better than the solved position

[@feitocomfruta]

+Pokemonix Aditya The need for order being outweighed by the need for novelty.

[@Raylock]

feitocomfruta well Tetris players I cannot help but neglect the cube as it's perfect in its own way perfection is non existing word after all

[@samaykumar6059]

I disagree. I always have 2 cubes lying on my desk and if I ever find them unsolved, I rush to it. Can't stand it being scrambled.

[@jessetorres4319]

Its probably only their for decoration LOL!

[@feitocomfruta]

I've gotta say, after watching this series so far, I'm happy they have Dr Somara as the host. Her voice is nice to listen to, and her delivery of the material is engaging. I had to study basic wavelength physics in college for part of my Speech Pathology degree, and I found the course to be a bit dull. I wonder how it will be if and when they discuss it here.

[@italktoomuch6442]

"Suppose you threw a 5kg ball up in the air, and then, you know, got out of the way because that could really hurt if it hits you." This is easier to understand than I thought it would be.

[@aarongould3538]

I can tell im going to watch this video at least 3 more times

[@cameronpaul9183]

No

[@b_08_amitkumarsahu90]

Aaron Gould me too

[@hitormisshuh]

Same

[@LearnersNation]

Nice

[@flinkoplanki1974]

This is my 4th time watching.....

[@achild5864]

I was getting it until the elevator thing ...

[@mr.klunee4103]

This really is not a good video for beginners; it moves too quickly to teach anything. For someone like me just watching for fun, sure. But not useful for trying to learn the information. Also the elevator graphic uses colors that make it hard to see the different arrows and stuff they add to it.

[@ngocminhhan4482]

omg same that's why i'm scrolling down here

[@swarnalatha5242]

Its basiclly a concept with which you can tell how much your weight will be on the weighing machine,based off of lifts acceleration and direction i know its a long time but hope it helps :)

[@Sinnbad21]

SWARNA LATHA What always confuses me is that if it takes 15 Newton’s of force to lift an object off the table, how would I actually be able to lift it if the law states that it’s pulling back down with the same force? Wouldn’t it just cancel each other out?

[@swarnalatha5242]

@@Sinnbad21 thats where u r getting it wrong. The newtons 3rd law is applivable only for push not for pull.

[@itsFisch]

I have this weird habit where I like to watch all these education physics videos after a physic exam....why....

[@Jazlynify]

hahaha I do that too

[@shravannani4704]

+Jazlyn Natalie I do

[@jake_runs_the_world]

Hahahha yeah XD

[@falsehoodbasher7240]

to know what u'r missing?

[@cameronpaul9183]

haha me too bro

[@pilar1904]

these crash course people are great teachers! much better than the ones in my personal experiences at least...

[@ГітаЗахир]

Apatheism so true

[@auroraautumn8764]

They don't have to teach behavior, why won't they be better. Try being a teacher for a day in your life and you will have a different perspective. I love teaching my content but I can't teach it fun when a bunch of kids are talking, arguing with each other or getting out of their seats which erupts in laughter. Once behavior is taught teaching becomes easier.

[@LearnersNation]

Yeah that's true, but did you understood everything she taught or may you just liked the video presentation? And understood much lesser than compared to real one.

[@lukast2784]

regular teachers can be trash...

[@pineapplepanda8444]

Same! there way better than class teaches

[@peekyoin8347]

I cant focus on the video because of my habit reading the comments while watching😂

[@lightsier]

British accents give me joy whenever I hear them, bless the British.

[@frankschneider6156]

+lightsier Ever experienced Cockney ?

[@edwardmcdonagh7309]

+Frank Schneider or scouse

[@frankschneider6156]

Edward McDOnagh equally bad ... I'm not even sure if what those natives are talking really qualifies as a language or if it is not rather a combination of grunt louds.

[@edwardmcdonagh7309]

Loud, strangely high pitched grunts

[@frankschneider6156]

Edward McDOnagh Are they also wearing bones in their nose ?

[@DanSolSko]

"And for that we're gonna turn to a physicist you've probably heard of" Me: BILL NYE THE SCIE....Oh.

[@lumeme9352]

@Merwin D'Souza I'M CALLING THE FBI PREPARE TO HAVE YOUR VODKA TAKEN!

[@GlamourCat1920]

SCIENCE RULES!

[@rafqatouma7735]

Sir Isaac Newton: For every action, there is an equal opposite reaction Hamilton fans: *screams in 13 different languages*

[@satuispunk]

Thanks to Hamilton our cabinet's fractured into factions..... Hehehehe

[@babatulani6361]

5:01 just completely clarifies my confusions in physics after 5 years.

[@omkarchavan5940]

👍

[@ASOUE]

+yrjosmiel73 SOOO True, I always wondered why we could move things if everything applies the same amount of force back.

[@lunacryst2110]

+yrjosmiel73 OHHHHHHHHHHHHHHHHHHHH!!!!!

[@joelchalla9603]

She's hot

[@lunacryst2110]

....

[@Libbyness]

I love her accent, not gonna lie. Especially how she says equilibrium :3

[@DrGrape-px7se]

Same

[@adityamunimala4885]

And she is an Indian

[@lukast2784]

uhhhhhhhhhhh

[@DonnyvanGoBlueYT]

BRA!!!!!!

[@happyhuman8549]

@@adityamunimala4885 xd australian nationality

[@samanthakimball6053]

when corona makes you watch these videos.

[@yungsmile7546]

bruh?

[@aidenschwerdtfeger6104]

Funny thing is that I’m actually here for a class during quarantine so you’re not wrong

[@jasonvelasco90]

​@@aidenschwerdtfeger6104 ditto

[@Deneirioo]

People just want to bring up Corona to bad cus it another way to get alot of likes

[@badtime6096]

@@Deneirioo that's pretty cool my guy!

[@andthatsondana]

My physics final is tomorrow. Wish me luck, I'm going to need it lmao

[@kaylieherrera9470]

I've learned more in this video than in my physics class all year.

[@Heavensrun]

Eeeeeh, I have an issue with how you describe the reason that the action and reaction forces don't cancel out. It is less about the difference between the sleigh vs the force on the ground and more about the fact that the forces are acting on different objects. Consider an astronaut pushing another astronaut in the depth of space. Each astronaut experiences an equal and opposite force, and there are NO OTHER FORCES acting on them, yet they still accelerate. Why? Because while the forces are equal and opposite, they are acting on _different objects_. You can pick up the mug, in spite of the equal and opposite reaction force, because the reaction force isn't acting on the same object. If force 1 is on object A, and force 2 is on object B, the fact that they're equal and opposite is irrelevant. They can't cancel if they're acting on different objects. The action force is object A acting on object B, the reaction is object B acting on object A. Each of these forces is free to induce acceleration on their respective objects.

[@Iffyish]

Jason Heavensrun thank you very much for the explanation

[@supreetsingh987]

I don't see how what she said contradicts what she said given that she specified what object each force was acting on. And why would anyone think 2 separate forces acting on 2 objects would effect each other.

[@burlofreak]

that's exactly what she said, except you sound stupid.

[@wareeshanadeem3940]

Ur words aren't even over in the keypad lady you type so much

[@qtMure]

Jason Heavensrun thanks for the answers to my physics quiz XD

[@blmandar]

Newton's 4th Law of Motion - "A Rubik's cube at unsolved position will continue to be in unsolved position unless it is acted upon by a external effort to change its state of being."

[@AAMEERAHMARIANO]

@CrashCourse I'm loving the Physics course and they are helping me so much. You teach better than in the school I was. I'm watching many times to get every point. Thank you for sharing these knowledges with us.

[@swarnalatha5242]

Sis what she is teaching is 6th grade stuff and if you are watching it again to get every point i am sorry you are just dumb

[@mdewolfe33]

Have a physics midterm tomorrow. Hopefully these help

[@dannydevito560]

same

[@sniperammow4865]

Matt DeWolfe I have physics nest semester, just practicing.

[@francis2339]

How did it go guys?

[@gomeezzzzz5213]

I skipped a huge part of my math book that talked about this stuff. when finals came i had to learn EVERYTHING in one night. this video helped a lot much love.

[@swarnalatha5242]

So you are saying ur exam was soo trash that a 10 min video could ans everything?

[@gomeezzzzz5213]

@@swarnalatha5242 yes thats exactly what im saying. and also this video explains it fast and detailed enough

[@trendteaser9333]

Why would you skip so much

[@gomeezzzzz5213]

@@trendteaser9333 we get too choose what to study first. i skipped the first lesson which was newtons law and kinda forgot about it

[@trendteaser9333]

@@gomeezzzzz5213 doesn't the teacher tell everyone the same lesson?

[@muammarssamad5357]

5:52 The teacher says: There would be no Christmas without physics. Me: Why he doesn't put a flying reindeer?

[@Lily-mm7dq]

How is it that I learn more in the night before a test from a woman I don't personally know than I do from my teacher! Thank you everybody at Crash Course!

[@emmanuelamoh7181]

1:25, I know this is a serious topic, but I just found it funny.

[@moneyinfluencer9274]

Her:no Christmas without physics Santa: are you sure about that

[@anitabhandary2902]

Thanks for being a grade teacher. My irl teacher can’t teach.

[@anitabhandary2902]

I am in 6th grade btw 😊

[@randybaker4675]

Thank you for taking the time to make these videos. I'm having a terrible time with my current professor and this has already helped! Godspeed!

[@GamegisKhan]

8:32 isnt that Newton's Second law?

[@cajuniky]

Sure is, good catch

[@cajuniky]

+Science Power I didnt notice, because as I watch this, I start spacing out on memories from studying Engineering Haha 😄

[@swarnalatha5242]

@@cajuniky sis this is taught in 6th grade not in engineering atleast speak a beliveable lie

[@cajuniky]

@@swarnalatha5242Lol I never said this was only taught in Engineering. These are the basic laws of movement/force. And used to form equations in 3D space with vectors, with advanced calculus, in Static and Dynamic physics in Engineering. What I was saying was, when I see any basic physics, I always think back to these courses. And also Relativity and Quantum physics. Which I dont even think is mandatory to take anymore where Im from, for Civil Eng at the Uni I was at, but that was 12 years ago 🤷‍♀️.. Idk why u assume Im lying 🤦‍♀️

[@FirstRisingSouI]

The thought bubble about the hockey rink wasn't timed well. It showed constant motion when Shini was talking about acceleration, and stopped the puck when Shini was talking about equilibrium. This might really confuse people who are learning this for the first time.

[@SpyrooTUR]

FirstRisingSouI oh wait wat

[@Cacciato]

At 8:23, isn't the force of tension the same as the force of gravity on the counterweight ? I mean Ft = m(c).g It's Just the only thing that i don't understand.

[@Langschwert25]

"F"ull = "M"etal "A"lchemist

[@cheroberts8958]

no

[@jasonstarrising]

:9

[@azlhiacneg]

Well I was like, "Let me watch some easy physics to procrastinate for this physics exam today". Then I realized how much basic physics I've forgotten... Well now I know why people hate physics so much...

[@omkarbhambure7461]

special appearance:professor Feynman!!!

[@no._.873]

I will never forget “Every action has an equal opposite reaction” thanks to Hamilton but at the same time i will never not sing that line.

[@mimipavey]

this genuinely might be the only reason i pass physics, thankyou so so much!!

[@nafrost2787]

Who needs notebooks when you have CrashCourse? I have a test on this in 4 days but I don't even look at what we have learned in class, I don't need it, I got Shini

[@aulid9607]

G in Olevels = 10m/s G in ALEVELs = 9.81 m/s

[@IoEstasCedonta]

3:40 - "...which is explained by Newton's third law... that's what we call the normal force." ...what? No, it isn't. Where gravity's concerned, the reaction force is the Earth being pulled. I'm not totally sure what the normal force's reaction is - I think it has to do with the stress on different parts of the object - but I know that when it comes to gravity, the reaction will always be the force on the other body, and the fact that the normal force is also equal and opposite in this case is a consequence of the fact we're considering a stationary object, not Newton's third law.

[@redwallzyl]

+IoEstasCedonta I'm not sure what your talking about. it sounded fine to me. i recall the same thing from my AP physics class a few years ago.

[@zanryll]

the normal reaction force actually comes from a few things, one of them being the electrostatic repulsion of the electrons in the outer shells of the atoms that make up the objects. If you think of the electrons with their like charges as similar to like poles of a magnet, you can see how this causes a reactionary force. The harder you push the magnet, the harder the magnet pushes back.

[@MWaheduzzamanKhan1]

+IoEstasCedonta You are correct. The action of "Earth pulling on the object" is equal to the reaction of "The object pulling on the Earth". In case of the Normal Force, the action of "The total electric/ other quantum phenomena repulsion by the electrons on the outer shell of the object toward the table" is equal to "The total repulsion by the table towards the object" both generating from being too close in the microscopic level. For an object resting on the table, the forces on the first group equals the forces on the second group, hence both forces on the object cancels out. If it didn't, the object will break through the table. Newtons law is also valid for a falling object, where there is no table to oppose the gravity. In that case, the force on the object is equal to the attraction force on earth by the object. But the net force on the object do not cancel out.

[@shreshthadavi141]

This is wonderful! I was waiting for this for such a long time.. Could you do some videos about electronics and stuff like that? Keep up the good work!

[@petermacdonough9077]

Thank you for posting this!! I have been studying to get into the Navy and I am on the Physical Science chapter. I have a better understanding by watching things in motion and film, and this video has helped a lot!!! :)

[@zcrazyg9114]

One does not simply "Throw" a 5kg bowling ball...

[@spam_musubi1]

At 1:23 I was dying of laughter 😂😭 I was watching this in class (everyone) and was the only one that was laughing .

[@TylerLauren.]

The quality of your videos are amazing, and also interesting! Thank you.

[@hudsonx3505]

when you have a science test tomorrow and forgot to study

[@harimcbride5017]

Legit me now

[@gabriele7059]

I forget the whole thing. My rise was approximately at the beginning. What a remarkable creature. So well spoken.

[@lejink]

Thanks for the upload! I'd like to see more of Shini, her accent is wonderful to listen to, she has a beautiful smile and she holds attention well

[@Malidictus]

This is a really odd way of handling the weight-counterweight example, considering the forces are linked. Gravity pulls both the weight and counterweight "down" with the same force while the lift and counterweight pull each other up by their own weight. Basically, the force acting on the lift is its own mass * gravity - the counterweight's mass times gravity, isn't it? All the rope and pully system does (assuming no stretching or friction) is to redirect the counterweight's weight up relative to the lift's weight, almost as though it were attached to a balloon, instead. I've done calculus and analytical physics in the university and your approach to jamming everything in the same colossal equation still confuses me greatly. It just seems so much simpler to take the maths step by step in what I presume is intended to be an introductory course in physics for people who haven't already studied physics. There are simpler ways to explain this.

[@rath60]

+Malidictus I really get your point but I think the idea is to quickly discribe the math with out it bogging down the physics although the math is the physics so... ?

[@omkarchavan5940]

I think they should have taken DOWN as positive... it would have been easy for solving and understanding...

[@Malidictus]

Jose Hernandez The problem, though, is it becomes a little bit TOO quick. Like I said - I'm able to follow reasonably fine, but I took analytical physics at the university. I already know this stuff. For someone walking into this Crash Course from a non-mathematical background, all of this would be terribly confusing. You can only do so much in a 10-minute video, I grant you this much, but I'd personally cut out some of the pictorial examples if it meant making the equations more accessible. In my experience, simply giving people an equation and saying "Right, this is how you do this!" just ends up being confusing. If you don't know the "why" behind mathematics, it really does sound like alien science.

[@charmingyoutuber2408]

@@Malidictus it doesn't. If you understand fractions, you can understand this video. Stop being such an "intellectual" douche .

[@maryjames9927]

Gosh i think I learn more in KZbin than my teacher's stuffs thinks that she knows too much while she was fooling us around"LOVE U YOU TUBE TEACHERS"got to understand alot

[@Araj213]

Newtons 4th law of motion: every book will be covered in dust unless and until and exteral exam acts on it😂😂

[@xochitlterrazas1149]

Got an Ap Physics Exam today and I decide to watch these the morning of

[@davidbarta9512]

Laws of motion do not work, My crush atracts me but I do not atract her. :)

[@rashiverma1151]

😥😥

[@hegrye]

Lol

[@satuispunk]

Dang, I feel you. Mine said that's she liked girls, but she's not into me and now I'm sad. Why am I writing this? In a physics video of all places 😂

[@nachannachle2706]

Most interesting video so far. It's nice to see the notions/concepts build up piece by piece. Still, so many ways to describe the same "event" and it's all down to mathematics.

[@rah9081]

"There will be no Christmas, without Physics "😄

[@somethingreal5042]

newtons 3rd law example: a gun fires, there is a recoil

[@RyanTaegan]

Hey Shini! I'm having my physics exam tomorrow and these videos really help! Keep going! 😊

[@liawxinyan]

I like how this is posted for me to revise for my physics test next week. Good timing!

[@Alverant]

Remember the PBS show "Mechanical Universe" in the 70s? They also did the moving parts of the equation. But they had little starbursts when factors canceled each other out.

[@gigijbijbj]

80's*

[@spaceinbetween6591]

Thats such an obscure reference

[@Alverant]

+IAintGivinOutMyRealNameOn KZbin Maybe, but it's this series's thematic ancestor. Early computer graphics and demonstrations. I loved it. This lecturer had this huge notebook and you could see the progress he made from beginning to end.

[@rowandoescovers]

glleg

[@coolmansam150]

Crash Course Engineering Next !?!?!?

[@ignacio560]

Sam Duke Its happening!

[@swarnalatha5242]

Bruh this is all 6th grade stuff

[@DinaKubba]

These videos are pretty helpful so far, but the timing was honestly bad, you guys should've started earlier since that the AP Physics exam will be next week.

[@JoshuaChowabc]

+Dina K. Because of weird American laws, I think taxes influence when seasons on CrashCourse starts and ends

[@plaiedesct]

+Dina K. You're in serious trouble if u use crash course as ur study guide.

[@JoshuaBorrow]

+Perseides Why? They often provide an interesting alternative approach that can help people with their understanding. The Astronomy crash course covered concepts last year up to end of undergrad level, just with less mathematics.

[@DinaKubba]

+Perseides It's definitely not the only resource that I would use for studying and AP course, but it would've been useful when I first started taking the course. I personally like to use simple videos to recap all topics.

[@JohnnyYenn]

I already had my mid term on first year mechanics. Would have been helpful like 2-3 months ago.

[@strawberriesandpeaches9816]

I have a question. Does Newton's 3rd law also apply to like when, you hit someone who's kinda stronger than you so you can feel the impact as well.

[@Zanityrey]

i love these ppl on this channel sm they give me hope in my school life

[@Jerome...]

Elevator > Lift. Elevators change your elevation. Lift should only go upward.

[@robertstiffler1251]

They lift you upward at a negative speed

[@Schindlabua]

+Mr. Poopybutthole mind = blown

[@ingridesquilla8664]

where can I get a lift straight to heaven?

[@thegaspatthegateway]

They lift you above the air in the elevator shaft? hehe jk your comment was funny

[@samrashafaq1717]

Robert Stiffler speed can never be negative

[@celestialskies-covers]

Okay, so Newton went and stopped a cow and got his first law: An object continues to be in a state of rest or motion unless acted upon. Then he gave the cow a little bit of force and then the cow said 'Ma' and so F = Ma Then he kicked the cow and here comes the third law. The cow kicked him back. This is how I remembered these laws.

[@Iffyish]

I love learning in my free time. Thanks for the videos! I'm about to start college, and these videos have definitely helped refresh my memory about what I've learned in high school while keeping me entertained by presenting new additional info.

[@Iffyish]

I also love the graphics because I learn best visually. Thanks again!

[@swarnalatha5242]

Excuse me? This is taught in 6th grade

[@Iffyish]

@@swarnalatha5242 not in detail where I live.

[@swarnalatha5242]

@@Iffyish kk no offence though

[@Iffyish]

@@swarnalatha5242 None taken, lol, schools here aren't great. Once got a bad grade on my trigonometry final in highschool, went back and checked, and some of the test answers were actually wrong. My teacher corrected it after - thankfully, she wasn't the type to outright ignore constructive criticism like some teachers.

[@brad.bryant]

these videos are great and all but I really just enjoy listening to her talk

[@ZulfaAbdallah-lz5lz]

I just like how she is explaining physics with such a smiling face i start loving phy but my finals r near i should have discover this early

[@legitgopnik8431]

This video cleared up a lot of things for me! Thank you for making this show!

[@WeAreGRID]

except thats not how equal and opposite reactions work! When you push on an object, its not the object pushing you back, its YOU pushing you back! In space, this is easily demonstrated because if you have two objects, floating side by side, and object A pushes on object B, they fly apart at half the force of the push, in opposite directions. Object B has not acted on object A, Object A has done all the force applying, but because nothing is stopping it from going in the opposite direction, like say the ground, or gravity, its force is applied equally between the objects, in equal, but opposite directions! Its still the "normal force" but its not the table pushing on your finger, its your finger pushing on your hand! Where things get tricky is when Object A and B have unequal masses, because if Object B is twice the mass, it doesnt receive as much acceleration, and effectively Object A pushes off of Object B, but it still causes Object B to drift off In the opposite direction! (just by a quarter the amount) Or, lets say Object A has a rocket, that lets it push against Object B, without getting pushed in the opposite direction, then something similar to what you described happens, because Object B was at rest, it resists change in acceleration, relative to its mass, it will attempt to squish Object A between the rocket and itself, until the rocket has applied enough force that it has the same velocity as Object A, its change in velocity becoming zero, as it is in space, and no other force is acting on it, it will then be in You guessed it, equilibrium! Like seriously guys, was i the only one that learned this from space first, and earth second? Also, fun fact, every time we launch something from the earth to space, we effectively slow the rotation of the earth by a smidge. It also happens any time we do a gravity assist around the moon, or another planet, or ourselves, we infinitesimally change the rotation period of the earth/moon/planet in question.

[@edskev7696]

As top of my year in theoretical physics and applied mathematics, I can inform you that you are incorrect. If you push on an object, it is slightly compressed, and in its attempt to reexpand it pushes back.

[@shreyajadhav5857]

+WeAreGRID You are incorrect if you are pushing yourself back .....then take the grape example the grapes are pushing themselves back .....nope ...well its has a long explaination but if you put your methods in the grape example...you will find yourself incorect!!

[@WeAreGRID]

Shreya Jadhav yeah except even thats not the normal force, its surface tension, the only force being applied is gravity stretching the tin foil.

[@WeAreGRID]

***** well sure if you get to the advanced simulations such as that, then yes, everything has a compressibility, but ignoring compressibility (such as this episodes massless weightless examples) it just doesnt work the way they explain. Its not the object exerting force, its you exerting force on yourself and the object.

[@edskev7696]

+WeAreGRID if the object wasn't there, you could do the exact same motions exerting exactly the same amount of energy with your arms or legs, and not recieve any force upon yourself. The presence of the object causes the force on you to be felt, thus it is the object exerting a force on you. I agree that this is a poor explanation, and I'm not going to claim that the video does a great job at explaining things, but ultimately these 'advanced simulations' as you call them are trying to represent what actually happens. Thinking about the subtleties of whats going on may help you to see the reality of things.

[@tdpack2003]

I'm in love with Shini!

[@juvojunior7505]

That was quite the complicated method. Also could be done by just calculating the resultant force by multiplying the total mass of contents in the elevator by gravity and subtract the mass of the counterweight also multiplied by gravity to find the resultant force. Since we know the total mass of all bodies in the system calculating to be the mass of the counterweight plus the mass of the elevator we can divide the resultant for the system by the total mass to find acceleration.

[@bullpup1337]

Juvo Junior That is, in essence, what she did. She just explained it better.

[@georgiamillar4001]

No Christmas without physics...I-

[@liz_3d]

8:50 It's quite confusing that the Tension Force on the counterweight is drawn smaller than the one on the elevator, since these should be equal as they are in the equation. This Force should be larger than the Gravitational Force since it is accelerating upwards. I know it's just an illustration but it might still confuse a lot of people.

[@lottiex9597]

this was rlly useful I hopefully I will ace my physics force test cause its today

[@welog7884]

There would be no christmas without physics. *Holds up a finger* ... *Slowly pulls it back*

[@sentoria7702]

thank you so much for making this wonderful video free!!

[@imogen-q4s]

Wow just wow I love these videos lots of info and great for understanding for younger watchers! continue with the good work pls! xx

[@IceMetalPunk]

I have a question. Way back in my high school physics class, we had a substitute teacher one day, and he asked if anyone could tell him what momentum was. So I said it was a measurement of inertia. He said he supposed that was right, but he was looking for the p=mv equation. I never really was confident in my answer; is it in fact accurate to think of momentum as a measurement of inertia?

[@robertstiffler1251]

Inertia is an object's resistance to changes in motion. It is an idea, not a quantity. Inertia is most closely related to mass. Momentum is the product of mass and velocity. It is a related but different quantity than just mass.

[@IceMetalPunk]

Mr. Poopybutthole I didn't say inertia and momentum were equivalent. I said momentum is *a measure* of inertia. Kind of how meters and length aren't equivalent, but meters are a measure of length.

[@syedshahabuddin1738]

Momentum is not the measure of inertia since inertia is independent of the velocity of the body and is mathematically equivalent to mass. Momentum however depends on the velocity of the body. So if two objects having same mass are moving with different velocities, their inertia will be same since masses are equal but momentum will be different. The idea of momentum was introduced for the calculation of force since rate of change of momentum is directly proportional to applied force.

[@IceMetalPunk]

Syed Shahabuddin Ah, okay, that does make sense...but does that mean that light doesn't have any inertia, since it has no mass (even though it does have momentum)?

[@robertstiffler1251]

+IceMetalPunk You could say that mass is the measure for inertia. Light is a special case because using the classical equation p=mv for momentum light shouldn't have momentum either. In relativity momentum is defined differently.

[@guidethanakorn3982]

When you sleep in class, so you end up watching this at night trying to do homework

[@otshepengmoloto4946]

Thank you for being such a great teacher I hope you keep on making greater videos

[@ghostly3027]

love these vids, helping me through college one at a time! thanks for all that you folk at crash course do!

[@syedlatief943]

I think there is only only one law that is force is equal to mass times acceleration. Three laws are just manipulation of applied force.

[@nels6991]

When the magnitude of Fg and Ft are both 5 Newtons, should Fg be written as -5 instead of 5 so they add up to zero?

[@MitsugashiraEnoko]

0:40 Snake? Solid Snake? Man, I did not expect to see him during Physics class.

[@rajivmalhotra6227]

8:32 *Second law Not first law (Inertia)

[@estebancx7805]

I love this channel, please never stop it..!

[@vivianchou3465]

The third law reminds me of fractions. If the numerator is less then the denominator, then the foil is able to support it's weight. If the numerator is heavier, then the grapes would break through the foil.

[@joenuttall4711]

Vivian Chou same. Physics for you tomorrow?

[@sicilereveriechanson5056]

Newton's 3rd Law in a nutshell: "Push a box and the box pushes back to you. Kick a ball and also kicks you. Gaze into the abyss and the abyss gazes back to you."

[@superj1e2z6]

In before thumbnail.

[@bobjohnson6917]

Same

[@Bacon12954]

Same

[@adammehdi9205]

+superj1e2z6 yep

[@GeneralKaleRan]

+superj1e2z6 Same

[@callumdenault2895]

Yep

[@renendarkfire]

I have one question.... How did that guy at 1:24 not shatter his foot?!?!?!

[@oriselkirk2726]

He's a fucking cartoon.

[@hackyboi175]

@@oriselkirk2726 it's a joke. Jeez

[@conntoons_4848]

😂😂😂😂😂😂😂

[@markiesangamingandvlogs6155]

can somebody put oriskrk on reddit

[@jasonstarrising]

@@oriselkirk2726 dumbfuck

[@fridaramoscasas9970]

Thank you for explaining my entire science chapter❤️❤️❤️👌👌👌👌

[@ellafleck1307]

Thank you for this video! It helped sooo much, I'm a fifth grader trying to learn the order.