Torque: Crash Course Physics #12

[@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

[@SnoozeTheRecluse]

I'm learning my whole semester in one day

[@phathumudau223]

"you know how physics loves ramps, especially hypothetical ramps" , please tell me something more true than this

[@aksharaa5376]

passive-aggressive physicists

[@DapaChrons]

the key to watching these videos is to pause to think on and rewatch certain moments if you don't grasp them immediately. These videos also help in conjunction with reading or other videos. I'm here because my physics textbook didn't explain what torque was but launched into a 15 page discussion of magnetic torque

[@pandacutiesuperstar]

Its not that she speaks too fast, its that they expect you to have a background in this, its like a review

[@pranavkulkarni1414]

The jump cuts don't help either.

[@gusbisbal9803]

I have a back ground in this and its treating the fundamentals like its something we can just skip over. Like the units of torque are crucial to understanding torque. ITS NOT A FORCE!!! is what it tells you. As soon as you say its not a force then the question of what is it really???? can be answered. Thats when you begin to understand it.

[@barockassegid9912]

@@gusbisbal9803 This is called CRASH COURSE FOR A REASON. SHES SUPPOSED TO HELP REVIEW THE BASIC TOPICS IF YOU WANT SOMEONE TO HOLD YOUR HAND AND WIPE YOUR NOSE FOR YOU, GO TO YOUR TEACHER OR KHAN ACADEMY

[@shreyaprakash]

For anyone watching Crash Coures physics for the first time: Dont get tensed by watching these videos.. These videos are best for reviewing the concepts after learning the topics beforehand.. They are not recommended for anyone who wants to learn these concepts afresh.. Dont freak out after watching these videos, it's fine!!

[@kikumayumi9219]

the whole point of crash courses is to get people an understanding of a subject, not to review it

[@shreyaprakash]

@@kikumayumi9219 Exactly! And that's what disappoints most of us watching the videos..

[@kikumayumi9219]

@@shreyaprakash how so does it disappoint us, this crash course was a great help for me when I watched it

[@shreyaprakash]

I think you must be having at least some basic understanding of these topics.. My point is that people who want to start learning physics or those who have no background knowledge of the subject will find it extremely hard to grasp the concept.. It's a generalized view..

[@xSkyHigh12]

I really like the way she... torque

[@caihui5697]

HAHAHA

[@enriquea96]

good one brah

[@marcelinatuszynska97]

OMG AHAHA. THIS SHOULD WE TOP COMMENT

[@enriquea96]

yes he definitely got me xD

[@wavinsouth7327]

loool

[@bootswiththefurr4718]

"Have you ever pulled a door open? Me too!" I love it. 1:04

[@NarekAvetisyan]

I understood none of this. But, I feel smarter after watching this video.

[@SunriseFireberry]

The One Ring comes third, but it rules them all!

[@benaaronmusic]

...and my axe!

[@arcaderockstar7536]

RISE!

[@ricodelta1]

I have a cock ring

[@ddmagee57]

A male chicken ring?

[@pietrocelano23]

One Ring to rule them all, One Ring to find them,One Ring to bring them all and in the darkness bind them.

I have a degree in theoretical physics, and I just adore this series!

[@KingJokerRock]

A science lesson with a mario box, the one ring, and a dragon ball.... I'M IN!

[@mukundyadav4445]

KingJokerRock also the ring is from 'lord of the ring'🍻🔥

[@noabsolutelynot3660]

@@mukundyadav4445 that's why he said "the one ring" that's what it's called

[@biggbuck9535]

Should've used a power ring from Sonic the hedgehog. Then it would've moved faster down the ramp? 🤔 Lol

[@begonthotiana9487]

my kind of lesson

[@andersalexanderandersen5022]

These courses are pretty good for brushing up on - or repeating - physics classes, but I don't think they're very useful as a introduction to the subject. I understand that you need to solve problems to get to the core of physics, but listing a bunch of equations and explain their consequences isn't going going to give most of the audience a deeper understanding (this is an assumption!). I know the course would be taught in a much slower pace, but for really interested audience with a first hands experience, this is not building a solid foundation (in my opinion). I think it should be a blog post deriving all the equations displayed in the video for those who need a solid understanding of the equations. Don't take me wrong here, but I think this would please a bigger audience than the current setup.

[@FirstRisingSouI]

I agree. I think it would be better if the math were mentioned for reference, but the instruction kept mostly to the conceptual.

[@IoEstasCedonta]

I'm not sure how much more conceptual you can get than this...

[@AlbertoMartinez-rk2lf]

You may be right in some way, but in my opinion the most important thing is how cool is this vid so people like me, with no background in physics, take interest in this topics

[@Csilaverte]

I disagree. Most of the edutainment videos on KZbin are lacking the solid, somewhat rigorous aspect of that particular branch of science they currently teaches. These CC Physics videos do not: they have it in the form of the necessary math. The best thing about them that they serve not just as introductions, but also -as you have stated- help brushing up on previously attained knowledge, refreshing them. I'll write the exact same thing i am fond to say about this topic: if you are not interested in the nuances of mathematics, physics is propably not for you.

[@Mukation]

That's why it's called "crash course". It's not meant to be equal to an actual physics course in a school.

[@yasmeenhayat1378]

I actually really enjoy how this course is set up. It explains the basic concepts behind the equations so that when you go and practice the skills, you have a general idea on how to tackle them. I have to agree with the feedback others have given - you do whizz through the material. However, this medium can handle that, as you can just replay portions of the KZbin video. Keep up the good work!

[@sumitjha9730]

Thisvideojusttaughtmenottousespacebarwhenyouspeak.Thankyou.

[@dylanfiore3718]

And know I realized why my eyes had been looking at an all jumbled.

[@daveforfav7650]

Thatsnicekeepitup

[@daveforfav7650]

Mohammedhedidntputaspacebarbeforethankyouitsaperiodthankyouforyourtime

[@milkywegian]

daveimgay

[@daveforfav7650]

Whyutellingmethat

[@Pipiopy]

as usual, it's going to take a week to assimilate and fully understand the video :)

[@oscaralonso4699]

same.

[@PuffleBuns]

isn't ur face profile from an anime? I think its name is Greed?

[@Pipiopy]

King PufflePuff spirited away

[@PuffleBuns]

Yeah, that's what I thought. xD

[@nathanj2439]

King PufflePuff its original name was No Face

[@wakimaniac]

I slept through a physics class one time because I was tired, they explained torque. The teacher wouldn't explain it again. It's been two years, but now I finally understand this concept. Thank you so very much.

[@jakubbuzalka2226]

This video feels like a huge injection of liquid physics into my brain. Thank you!

[@MartijnvanWensveen]

Moments of silence.. This video has none!

[@RainbowManification]

Nope, just inertia

[@shaheer_ghazi]

I just spent 5 minutes of my life opening and closing my door at difference angles and lever arms

[@ganaraminukshuk0]

"We have a box, a ring, and a marble." (Mario cube, LotR ring, and dragonball appear on ramp.) This is gonna be good.

[@karanmehta5753]

to everyone saying that she is talking really fast.. that is because (if you haven't noticed) the channels name is called crash course and hence they have to explain topics quickly. I think that these videos are like reference materials that you can use to understand concepts quickly once you have a brief idea of the concepts.

[@DanGash]

I'm giving Crash Course a shout out on my graduation... in 2 weeks!!

[@ogliara6473]

Thank you for helping me through my physics assignment. Great video!

[@cherri_tsuuuu]

now you know you should buy your future wife a box so you guys can have a smoother relationship

[@davet5223]

Don't forget to put the ring inside the box

[@zoeferrier858]

@@davet5223 Ayyyyy

[@minghuiliu451]

If kinetic friction is not allowed, why will the marble and the ring roll instead of slide down?

[@giovanniadelfio5378]

Thanks, this was the exact problem my professor asked me about in the oral exam!

[@zacharykrawczyk3942]

There's an error at 6:27 the second part of the equation has KErot labeled as "kinetic energy of translational motion" instead of "kinetic energy of rotational motion"

[@abdulrakeebalsarori8171]

I am sorry, but how would the box get down before the ball or the ring? We already assumed that the surface is frictionless and so there would be no friction force that would cause the ring, or the ball, to rotate. Therefore, there would be no loss( or transformation) of potential energy to rotational energy of either the box or the ball.

[@missychuu]

She is gorgeous btw.... And I love her hair 😍

[@willzer808]

God yes

[@pairot01]

She is, not that it matter really.

[@feldinho]

stop objectifying her! she's here to teach physics!

[@willzer808]

Felds Liscia whatever, everything is relevant

[@charliehutch3533]

go to India..they literally all look like her.:P:

[@Kronimiciad]

If the ramp only allows static friction and not kinetic friction, then the box shouldn't go anywhere if it doesn't rotate. In order for the box to slide down the ramp it needs kinetic friction. Static friction would mean that the box is stationary.

[@tommclean9208]

Im doing Marine Engineering where there is a dynamics module which I did just not understand at all, these videos are so useful. Thanks.

[@jomacr3]

I could not get through Corona virus distance learning without this. Thank you!

[@Lee_yourboylee]

Love it, a very helpful accompaniment to my textbooks. Thank you Crash Course.

[@rafaelwilliam3805]

7:17 i almost had a heart attack, i sat in the libary and thought it was a school shooting lol

[@SauceyNoodle]

Learning physics from Symmetra

[@imjustsayin34]

First time using crash course for physics and was expecting hank but I was pleasantly surprised the speed she talks is nice

[@FirstRisingSouI]

Watching at 1.5 speed because I'm a physics grad student, but I feel compelled to watch everything Crash Course puts out.

[@HonestUsedCarReviews]

𝐓𝐨𝐫𝐪𝐮𝐞 𝐰𝐢𝐧𝐬 𝐫𝐚𝐜𝐞𝐬

[@josephpark2093]

This looks threatening.

[@safa9408]

My head has blown up, I wanna cry, and my acne is back after watching one video

[@audreyandremington5265]

I'll never watch LOTR the same way again.

[@ezekiel0606]

that pyshics theme song intro gave me chills just like the philosophy one

[@alluringorchid5725]

Thanks for helping me out with class 11 physics . Exam tomorrow

[@nathanbanks2354]

I love the Elvish characters inscribed on the ring! Now I know why it's difficult to roll a ring into a fiery volcano--it's better to get someone to bite it off your hand and fall instead.

[@stephaniejoelstro1762]

This series is so good.

[@En_theo]

@5:05 Should it not be "kinetical energy of rotational..." in the bottom equation ?

[@nekomatafuyu]

If the ramp is perfectly slippery, I'm wondering if the marble and ring would start rotating in the first place. As I'm picturing it in my mind, they start rotating due to the frictional force where they contact the ramp, but that force isn't there in this example (otherwise the block wouldn't slide (or at least would lose energy due to the friction)).

[@Rhaegar19]

Rolling objects use static friction because the point where they touch the ramp isn't actually moving (see last video).

[@McGeias]

+Rhaegar19 no no no. The last video was an example of rolling without slipping. A frictionless ramp has infinite slip. There is no counterforce in this hypothetical example turning linear momentum into rotational momentum. Gravity does not impart spin magically. It's a linear force. It the surface friction that converts linear motion into rotational motion. That friction has been eliminated in this example. This is all just wrong.

[@Rhaegar19]

+McGeias Everything you're saying is right, except the ramp isn't frictionless. It has static friction. Rolling objects use static friction to convert linear motion to rotation. If you don't believe me or Dr. Somara, google it for yourself.

[@sunrise682]

I swear to god no matter what im learning theres a crash course for it

[@williamcoley1]

If the ramp has no kinetic friction, then there is nothing to start the rolling motion of the ball and ring, ergo they would all reach the bottom of the ramp at the same time.

[@seaniwu]

Linear momentum is the product of moment of inertia and the angular velocity if and only if the axis of rotation of that body is a principle axis

[@voidspork7150]

Note that the ramp is frictionless. If the ramp had friction, the marble and ring would likely get down faster (specifically, the marble) because rolling friction is less powerful than static/sliding friction. That said, the example is meant to illustrate how torque and conservation of energy work, so mentioning friction would be counterproductive to the video.

[@asadgandapur9950]

kindly also make a video on projectile motion!

[@madLphnt]

The one youtube vid i look forward to all week!!! awesome

[@madamii]

I'm 13 in eight grade and I'm watching this because we have to learn about it soon. Im trying to be above everyone else!!!!

[@victorianightshade4237]

Just refreshed and boom

[@KrutarthBhatt1]

Mr.Green , this kind of videos make crash course my favorite channel.

[@damienscullytoo]

these physics videos are really helpful especially before my test

[@davidlei3097]

At 5:07, there is an error. The bottom part is suppose to say "rotational motion", not "translational motion".

[@theblackreaper4395]

Loved the video but in the case of the ramp, I'm pretty sure that friction between the box and ramp is kinetic, there is relative motion B/w the two surfaces..

[@Alesster101]

This video cured my insomnia. Good morning guys.

[@vicraaiman1205]

What's about the friction they have when goes down? The box has more surface than the marble and ring, it means the box have more friction than the other. So it will be slowed down

[@nobodyofnaught2]

Why is it that the Marble and Ring even start rolling rather than simply sliding down the ramp with no rotation just like the box? I think there's something about the interaction of the hypothetical scenario where Static Friction exits but Kinetic Friction does not but I can't wrap my head around it.

[@fredasanders3948]

Hi this is Arwen I love Crash Course!!!!!

[@ahmadzaidan7693]

i like this

[@himanshuoswal3540]

6:57 One ring to bring them all , one ring to find them all , One ring to rule them all.

[@laserwolf65]

Am I the only one who thinks that Physics is too technical a subject to be adequately explained to the layman in a series like this, or am I just stupid and unable to grasp Physics?

[@WeAreGRID]

its crash course, its basically assuming that you have either a background in the subject or are studying more than just this series. in my opinion she speaks way too quickly, each eopisode is a whole lesson, if a teacher was doing this each video would take an hour to demonstrate all the involved factors.

[@G_de_Coligny]

agreed the girl talk way to fast. Had a feeling like vertigo just because of the speed of her speech, before being able to understand the words she was saying. I,m non native in english that might have made it worse... but it's not a rap battle... slow down pretty please...

[@ph0n61234]

Not sure if speaking fast is a problem (and this one is pretty normal for me and I'm not even native speakers, for fast try CGP Grey channel :) ). The good thing about video is that you can always rollback to sections you didn't understand so you can learn at your own pace, it's the whole point actuallly.

[@G_de_Coligny]

for me it's too fast end of story. a good video should not have to be rewinded so you can grab the words. and the flow is definitely faster than other tutorial videos.

[@charliehutch3533]

or are you 'grasping' for replies?

[@filipfilipovic2974]

It was interesting listening to her torque about talk.

[@bennemann]

At 5:05 there is a mistake in the video: it shows "translational motion" for the second line too, which shold be "rotational motion".

[@InventTwig]

Correction ! : even if there is no external torque on a 'system of particles'/'particles' angular momentum is not always conserved(only for some special points. angular momentum wrt to allpoints is conserved when the rotating body does not have any angular acceleration AND the axis of rotation passes through COM. angular momentum of a point can change depending on from where you observe it (both in magnitude and direction).

[@alexsarullo3753]

The ramp example is flawed. For rotational energy to be taken into account, friction must exist to make the ring/marble spin. If the object make contact with a 0 friction surface, they cannot engage in spinning, they would just slide down the ramp.

[@lightspeed2014]

Alex Sarullo agreed

[@lightspeed2014]

It’s like kinetic friction works for the ring and the marble but not the box

[@linshuang]

That’s crazy, I thought the box would be last and ring would be first since it looks like a wheels. Thanks Dr Shini Somara!

[@DMikov]

I love your videos! please keep it up! May I kindly suggest to take a moment to breath... hehehe the paste is so fast! :) lil breaks :))

[@edwardmcdonagh7309]

you explained this way better than my university lecturer, good job!

[@naserahmed9874]

Did she give a lecture or she read out the lecture? How is it possible to continuously give a lecture like this?

[@adriel4040]

Okay, some of this stuff is a bit confusing but so much more confusing is the way teachers explain it in class. I swear i learned more in the last 10 mins than the last three weeks.

[@user-jy3lt3dn1r]

The short video really did good job to make a brief interview of phsical knowledge.

[@Roman-us2fp]

I tried calculating who would win the race but then I realized that the ramp was hypothetical so all of my calculations were wrong.

[@user-xf9sw4wr8f]

Good video

[@ImChrisNotChrist]

As a car guy, I very much appreciated that video. Solid host too

[@scorpioninpink]

The only topic in Physics that I actually know at least a little.

[@arunsharma4221]

Thanks a lot mam 😊 . You are awesome

[@TheBreaded]

If there is no friction on the ramp, the marble and ring wouldn't spin as they went down the ramp. They would just slide like the box does, at the same velocity as the box.

[@Rhaegar19]

You're right, but there is friction on the ramp!

[@nandodando9695]

That was clear and went right in. Thanks

[@krossbow_]

I graduated 5 years ago, im a veterinarian, why do i enjoy learning about torque

[@fahamedi]

They could've mentioned the physics of backflips, because when you jump and tuck your kness you decrease the moment of inertia of your body and you rotate faster due to conservation of angular momentum

[@bidishamukherjee3936]

best best best best best!!!!! i could not get the chapter while reading from book but crashcourse made me understand it soooooooooooooooooo wel!!!!! thanks a lot lot

[@fabd1923]

this video was very helpful, thanks guys

[@eefje9122]

at 5:07 the 2nd equation should be kinetic energy of ROTATIONAL energy, not TRANSLATIONAL energy

[@sciencelover2342]

If there is no kinetic friction, I don't think an object will roll.

[@danilooliveira6580]

what I was think was, wasn't the marble and the ring also supposed to just slide the ramp ? I mean, they need friction to roll.

[@Woad25]

No it still using static friction to roll. Remember, the point at the bottom of a round object as it rolls is stationary, assuming there's no slipping. So because it technically doesn't move you'd be using static friction.

[@orcushelvetii9613]

Thinking almost the same. But as there is a little static friction at the start, they will make a verry little bit of rotation just at the start, and then just keep sliding (with this little initial rotation). So, in a unperceptible way, i think the box arrives first.

[@heysoymarvin]

But there is static friction, so I think that's why they spun

[@joshuajonme48]

Friction is what prevents an object from moving down a ramp, not what helps move it. The reason why the objects move down the ramp is the force the gravity. The force of gravity is always straight down to the Earth's center, so the component of gravity aligned going down the ramp is what moves the object down. Friction (static or kinetic) would oppose the force of gravity. The object moves when the force of gravity aligned with the ramp is greater than friction. Reasons why she is considering static friction but not kinetic friction: If there is static friction, an object that rotates about an axis, such as a sphere, will not slip. Static friction gives a force of gravity. The force gravity will cause translational motion, while that initial static friction will cause rotational motion. For objects that do not have rotational motion, such as the cube, will have no affect from that initial static friction other than breaking through the threshold of friction. If there is not kinetic friction, then we won't lose energy when moving down the ramp. If there was kinetic energy, the cube will move down the ramp much slower than the ring or the sphere because more of its surface is in contact with the ramp to be affected by friction. Kinetic friction causes energy lost, so rotational energy and kinetic energy will not equal potential energy as the video shows. Also if there was kinetic friction, the results of the race would be different. The sphere is only in contact with the surface at one point, so it would have the least lost of energy from kinetic friction and will get to the bottom first. If I made any mistakes or left out any important information, please let me know.

[@marinairitsyan]

Very detailed explanation. Thank you!!

[@9000Arko]

dont you love when Pharah is teaching you about torque

[@RHTQ1]

Anyone else here studying for online makeup AP exams because of the stupid submit glitch? Because I am so upset about it... I was so confident about those other FRQs!😭😭😭

[@SquidTheSyd]

This video gets real, quick.

[@pwa3094]

I would challenge the outcome of the Ramp Race. If there is no kinetic friction on the ENTIRE ramp, then I do not believe there would not be any source of energy (torque) to rotate the marble or the ring. Hence the initial kinetic energy of the ring or marble would not be converted to rotational energy in the marble or the ring. Also since the only forces acting on all three objects, absent kinetic friction, would be "g" (gravity) and air resistance, I think the ring would win the race because it offers a smaller surface area for air molecules to act upon (drag), ignoring the effects the race because it offers a smaller surface area for air molecules to act upon (drag), ignoring the effects of laminar flow and potential vortices. thoughts?

[@secondo92]

Yeah you need friction in order to make the marble and the ring rotate. But since there was no friction on the ramp, the marble and the ring shouldn't rotate, they should just slide down the ramp. Since the ring is tiny and hollow I assume it has the lowest mass of all 3 and thus less inertia. Less inertia means higher velocity when you convert potential energy into kinetic energy. You are right.

[@frank260332]

Another person who has sussed out the teacher as not living in the real world.

[@adamlevy8971]

These videos are incredible. They are really helping me with my college course. Thank you! :)

[@shairiaaz8298]

i am really surprised how you taught that........i didn't ever felt it that easy and intresting......i must say good job

[@infinitasalo472]

This helps a lot, just what I need for exam review!

[@AmirMohammad-fd9nr]

that helps me a lot .GREAT THANKS for your useful videos.

[@skkhan-jg4jk]

U explaination is awesome my mind blows up

[@terrysullivan5276]

thanks...im finally read for my test tomorow