Collisions: Crash Course Physics #10

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  • เผยแพร่เมื่อ 4 พ.ย. 2024

ความคิดเห็น • 597

  • @crashcourse
    @crashcourse  ปีที่แล้ว +19

    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

  • @aidanc7578
    @aidanc7578 8 ปีที่แล้ว +758

    Hey Crash Course
    I was wondering if you guys could maybe start a series on music theory. It would be nice to have for musicians wanting to improve their work. It could cover topics such as chord progression, scales, Minor/Major...etc.
    If you read this comment please consider, and thanks for taking the time to read it. Keep up the good work.

    • @Shevzon
      @Shevzon 5 ปีที่แล้ว +19

      Totally yes, same here i need music theory too.

    • @jaredcortes366
      @jaredcortes366 5 ปีที่แล้ว +6

      Yes pleaseee!! I'm certain many people will benefit from this too!

    • @timandersson7372
      @timandersson7372 5 ปีที่แล้ว +12

      There's a book called 'The Theory of Sound' by Baron J.W.S. Rayleigh and the first chapter of vol I is all about musical notes and the ratio relations between them. pdf available upon a googling and it's well interesting

    • @karleyv8180
      @karleyv8180 4 ปีที่แล้ว +5

      YES best idea I’ve ever heard on TH-cam

  • @ruhaanchopra8878
    @ruhaanchopra8878 5 ปีที่แล้ว +154

    She speaks so flawlessly!! And clearly !!! She can simplify even the hardest of the topics !!!

  • @joshatwwc
    @joshatwwc 5 ปีที่แล้ว +22

    Studying with TH-cam is easier than trying to sit through class. If I don't catch something I can always go back and rewatch it and better understand. Whereas in a classroom I'm left numb from not catching everything and hence don't learn a damned thing. Thank you for your videos they are much appreciated.

  • @katiethompson8995
    @katiethompson8995 8 ปีที่แล้ว +273

    Just took my physics final today. these videos were really helpful to review with. 😊

    • @crashcourse
      @crashcourse  8 ปีที่แล้ว +36

      Great!
      -Nick J.

    • @Overkillermark2
      @Overkillermark2 8 ปีที่แล้ว +24

      *Is just watching due to nerdism*

    • @MegaFarinato
      @MegaFarinato 8 ปีที่แล้ว +1

      You might have to wait to see if that statement is true or false.

    • @wavinsouth7327
      @wavinsouth7327 8 ปีที่แล้ว

      +Overkillermark2 Bruh!! :)

    • @katiethompson8995
      @katiethompson8995 8 ปีที่แล้ว +3

      +MegaFarinato I say they were. I got an 89!!! 😁

  • @MrMineHeads.
    @MrMineHeads. 8 ปีที่แล้ว +425

    Yes, yes.. mmhm
    I understand...
    some of these words

    • @piercehakola4085
      @piercehakola4085 7 ปีที่แล้ว +3

      😂

    • @zub4516
      @zub4516 6 ปีที่แล้ว +1

      I can pretty much relate...

    • @Vividlyvanilla
      @Vividlyvanilla 5 ปีที่แล้ว +1

      i relate so much =D

    • @MrJayPuff
      @MrJayPuff 4 ปีที่แล้ว

      Just watch it like 4 times u’ll get it, dat what I did

  • @alexflohr1453
    @alexflohr1453 8 ปีที่แล้ว +11

    The day has finally come when CRASHCOURSE does a video on collisions!!! :)

  • @gbizy
    @gbizy 8 ปีที่แล้ว +867

    Collision Course Physics

    • @crashcourse
      @crashcourse  8 ปีที่แล้ว +243

      How did this not occur to ANYONE else??? Hats off to you.
      -Nick J.

    • @ace_stealth251ace9
      @ace_stealth251ace9 8 ปีที่แล้ว +5

      I do not understand can you please explain to me

    • @RockStar-gs1ik
      @RockStar-gs1ik 8 ปีที่แล้ว +1

      The Commentator f

    • @ranshibuki9659
      @ranshibuki9659 8 ปีที่แล้ว +1

      they should change the playlist name

    • @britterthecritter4531
      @britterthecritter4531 7 ปีที่แล้ว +23

      crash = collision
      crash course = collision course

  • @leeroyjenkins610
    @leeroyjenkins610 8 ปีที่แล้ว +368

    How do I manage to hate school so much, yet still watch every Crash Course video?

    • @Matthew-lu4sf
      @Matthew-lu4sf 8 ปีที่แล้ว +11

      No homework?

    • @maximusdizon7267
      @maximusdizon7267 8 ปีที่แล้ว +4

      +Matthew Kessler but homework is important so we can apply what we learned.

    • @Skellborn
      @Skellborn 8 ปีที่แล้ว +25

      You aren't forced to think too heavily about the topics at times you don't want to.

    • @pepegasadge2977
      @pepegasadge2977 8 ปีที่แล้ว +13

      Because school offers so many boring physics topics and boring ways to learn them.

    • @VR_Wizard
      @VR_Wizard 8 ปีที่แล้ว +11

      Try to ask your teachers questions about things you learned here at crash course and which you wanna learn more about.

  • @tangerinesandvibes
    @tangerinesandvibes 5 ปีที่แล้ว +160

    me: im going to read my barron's book for physics
    me instead: watches physics crash course while debating making brownies
    update: i made the brownies and will be giving them to my classmates tomorrow

  • @X-3K
    @X-3K 8 ปีที่แล้ว +375

    Speedy thing goes in, Speedy thing comes out.

    • @Amsirak88
      @Amsirak88 8 ปีที่แล้ว +1

      👍

    • @Amsirak88
      @Amsirak88 8 ปีที่แล้ว

      👍

    • @Kumaryoku
      @Kumaryoku 8 ปีที่แล้ว +7

      You can't explain that!

    • @Arthera0
      @Arthera0 8 ปีที่แล้ว +15

      ooh now I want to play portal 2 all over again. Don't help me procrastinate ;p.

    • @martinowong
      @martinowong 8 ปีที่แล้ว +10

      i understand the portal reference, but I don't know why I first read this in cgp grey's voice

  • @DeadPyro96
    @DeadPyro96 8 ปีที่แล้ว +6

    Another great episode! Seriously don't understand how people can find these incomprehensible. You can't dumb it down much more, if you actually want to learn something.

  • @jasonl.n.williams9380
    @jasonl.n.williams9380 6 ปีที่แล้ว +457

    This was uploaded...
    ...the day after my physics exam...

  • @qianweijia1
    @qianweijia1 8 ปีที่แล้ว +14

    This speaker has like the perfect voice for explaining things on the internet

  • @sharvanij2772
    @sharvanij2772 8 ปีที่แล้ว +70

    This video helped me understand this concept just in time for the physics subject test this Saturday! All the love, crash course. xoxo

    • @crashcourse
      @crashcourse  8 ปีที่แล้ว +11

      Woohoo!
      -Nick J.

    • @AldeyWP
      @AldeyWP 8 ปีที่แล้ว +2

      Hey +CrashCourse, after this series is done, will you guys make a Crash Course about the Modern Physics (Quantum)? Pretty Please? I hope there's math too...

  • @larto42
    @larto42 8 ปีที่แล้ว +11

    So beautiful gradients at the end! Great job as always graphics team :D

  • @ohthatsnot_
    @ohthatsnot_ 8 ปีที่แล้ว +7

    Can't wait until we start discussing electricity and electric circuits! These physics episodes are the highlight of my Fridays :D

  • @val71999
    @val71999 5 ปีที่แล้ว +7

    how is it that i can have a teacher tell me something for an entire semester but won't understand it until i watch a 10 minute crash course video? i'm killing this physics final today!

  • @tiuk23
    @tiuk23 8 ปีที่แล้ว +6

    I'm literally in love with this host. She's the best one in teaching physics.

  • @janedoe4339
    @janedoe4339 7 ปีที่แล้ว +1

    We have slow-comprehending brains (in that it takes our brain longer to translate what our ears are hearing) (autism) so the video "words" were too fast for us to comprehend but the photos / examples were GREAT!

  • @jedwardfanxox6
    @jedwardfanxox6 8 ปีที่แล้ว +64

    yes queen

  • @Lee_yourboylee
    @Lee_yourboylee 8 ปีที่แล้ว +5

    Enjoyed your contribution to the programme about the battle of jutland on the bbc, shini. Very interesting.
    Really liking CCP, too.

  • @4tytude
    @4tytude 4 ปีที่แล้ว +1

    thank you!!! thank you for helping me to find the joy of learning this! (instead of just memorizing useless formulas that I don't get where did those derive from!)

  • @nai.888
    @nai.888 4 ปีที่แล้ว +15

    1:48
    i really expected that cat to yowl and fly away from the bag of leaves

  • @kieranelson7754
    @kieranelson7754 8 ปีที่แล้ว +6

    I was stressing so much about 9 mins and 20 seconds ago, these videos are such great review tools!!

  • @ranshibuki9659
    @ranshibuki9659 8 ปีที่แล้ว +140

    "every action has and equal and opposite reaction."
    -except when we both start rappin!-

    • @tadaiyoradima
      @tadaiyoradima 6 ปีที่แล้ว +4

      mgk vs eminem

    • @shards4285
      @shards4285 5 ปีที่แล้ว +6

      im satisfied with your pun, its non-stop. You have no idea how long i've waited for this.

    • @kolbeowen3052
      @kolbeowen3052 4 ปีที่แล้ว +5

      Isaac Newton v bill nye

    • @italobeltran1316
      @italobeltran1316 4 ปีที่แล้ว +3

      I’ve accelerated the mind of mankind

    • @ectoOLDACC
      @ectoOLDACC 4 ปีที่แล้ว +3

      The integral sec y dy from 0 to 1/6 of π is log to base e of √3 times the 64th power of what?

  • @mechasentai
    @mechasentai 8 ปีที่แล้ว

    Crash course is the best series ever.

  • @dennisdonutshovel6893
    @dennisdonutshovel6893 5 ปีที่แล้ว +2

    The ball equation on when the ball hits the wall and changes its force in half a second. The equation itself was correct but the answer is 3.125. This is important for people taking the AP Physics C test, for they need you to round to the nearest 3 decimals.

  • @mozayeniml
    @mozayeniml 7 ปีที่แล้ว +87

    I honestly though she said a bag of bees rolling down a hill that would be easy to stop.
    NOTE DO NOT ATTEMPT TO STOP A BAG OF BEES WITH BEAR HANDS.

  • @Achieveyourgoals-jv3nw
    @Achieveyourgoals-jv3nw 13 วันที่ผ่านมา

    Brilliant work and explained very well🫶

  • @MilesQuickster
    @MilesQuickster 7 ปีที่แล้ว +45

    Perfectly inelastic?? UGH, ECONOMICS!

  • @925LY
    @925LY 7 ปีที่แล้ว +299

    Please fix that rubix cube, it's driving me insane.

  • @nanidachamman2645
    @nanidachamman2645 7 ปีที่แล้ว +1

    came fo the knowledge stayed 4 the backgrounds, really love the animation guys , .......gr8 movez...... keep it up.

  • @jfield7448
    @jfield7448 5 ปีที่แล้ว

    Thank You so much Crash Course

  • @DigiWorldOne
    @DigiWorldOne 8 ปีที่แล้ว +19

    *"Momentum, the Product of Mass and Velocity is conserved between portals. In Laymen's terms, Speedy thing goes in, Speedy thing comes out."*

  • @TheFireflyGrave
    @TheFireflyGrave 8 ปีที่แล้ว +3

    I"m surprised by how much I learned from this video.

  • @swr1240
    @swr1240 8 ปีที่แล้ว +2

    I am literally in love with this person.

  • @SamSClair
    @SamSClair 8 ปีที่แล้ว +1

    Big love from everyone revising for M1 in England!!

  • @Lamplovr
    @Lamplovr ปีที่แล้ว

    Literally so helpful

  • @elipantoine
    @elipantoine 8 ปีที่แล้ว +5

    I don't know who you are and I don't like the fact that you're not John or Hank Green but I will live with it since you have the most gorgeous accent I've ever heard

  • @sandygehrmann6309
    @sandygehrmann6309 8 ปีที่แล้ว +3

    My science test is on Tuesday... please finish the series before then!!!
    That would be amazing for my revision :)

  • @iceeprincess1
    @iceeprincess1 4 ปีที่แล้ว

    I love this teacher so much

  • @princejohn5723
    @princejohn5723 4 ปีที่แล้ว +2

    This is a great video!! Thank you!! Also love how the pool table scenes have that background noise. So creative!! Haha!!

  • @microdavid7098
    @microdavid7098 5 ปีที่แล้ว +2

    In Highschool, Kenya, we call it the Centre of Gravity, not mass. Not much of a difference, but it shows how different our curriculum is.

  • @stephendean2896
    @stephendean2896 4 ปีที่แล้ว

    I was hoping that it would be my favorite narrator when clicking this on the video. Luckily it was, which means my day is off to a good start

  • @abrahambrambila2465
    @abrahambrambila2465 8 ปีที่แล้ว +32

    brains and beauty.

  • @DracarmenWinterspring
    @DracarmenWinterspring 8 ปีที่แล้ว +3

    7:40 more like 2/3 of the distance between the centers of the balls, not the stick (assuming the stick itself is massless). This might not be significant for a long enough stick and balanced balls, but it's significant when calculating a more skewed system. Like the center of mass of a solar system (which can be inside its star or very near its surface).

  • @WebGuy1000
    @WebGuy1000 8 ปีที่แล้ว +12

    What's the difference between inertia and momentum? Those words both mean the tendency of object to stay in motion, right? Don't they both have the same equation too?

    • @taylorarch2661
      @taylorarch2661 8 ปีที่แล้ว +21

      Not really. Inertia has unique equations for different shapes (mostly variations of I =mr^2, such as I=2/5mr^2 for a solid sphere) while momentum has just the one (p=mv). The units for inertia are kgm^2 and the units for momentum are kgm/s. Inertia is a property of an object where it resists a change in motion, whereas momentum is just a statement of the velocity and mass of that object.

    • @WebGuy1000
      @WebGuy1000 8 ปีที่แล้ว +4

      Taylor Arch Thank you for your answer!

    • @nuclearwarfareaw
      @nuclearwarfareaw 8 ปีที่แล้ว +4

      You can't change inertia, but you can change momentum.
      Assume mass is conserved.

    • @alexxhall3022
      @alexxhall3022 8 ปีที่แล้ว

      WebGuy1000 - Domino Entertainment X-Men be fggcfff

    • @alexxhall3022
      @alexxhall3022 8 ปีที่แล้ว

      WebGuy1000 - Domino Entertainment X-Men be fggcfff

  • @buenchiko007
    @buenchiko007 8 ปีที่แล้ว

    woah, you uploading this right the before i have a test about collisions is amazing (for me)

  • @RickyG157
    @RickyG157 6 ปีที่แล้ว +1

    This video taught me more about collisions than what my teacher has in the past 2 weeks.

  • @WindImHaar
    @WindImHaar 8 ปีที่แล้ว +2

    I really like this series, you are all doing a brilliant job on the topics, animation, presentation and so on :D Only thing is that she talks a bit slow but that's ok cause we have the 2x speed option ^^

    • @thegamingwhovian8247
      @thegamingwhovian8247 8 ปีที่แล้ว +4

      That's the first time I've ever heard someone say that a crash course presenter talks too slowly

    • @nuclearwarfareaw
      @nuclearwarfareaw 8 ปีที่แล้ว

      +TheGamingWhovian I said that too! Even 2x speed is too slow.

    • @ChimeraGilbert
      @ChimeraGilbert 8 ปีที่แล้ว +1

      I wish they had a 10x speed but that probably still wouldn't be fast enough for me. If she's going too slow then you guys should probably move on to a video that's more involved because this is just a sliver of how involved physics can get.

  • @shadon1301
    @shadon1301 7 ปีที่แล้ว

    marvellous video

  • @saeedbaig4249
    @saeedbaig4249 7 ปีที่แล้ว +2

    2:20 - 2:31 = U said impulse is the "integral of the net force on an object over time", but then added "in other words- it's change in momentum". I'm confused. I thought force was change momentum (d(mv)/dt). How can impulse, which is the integral of force, also be a measure of change in momentum?

  • @SuperHappyHater
    @SuperHappyHater 8 ปีที่แล้ว +1

    I would really enjoy a series in which you guys talk about culturally significant music, from pop culture to the classics. I often feel like uncultured swine when a song comes on the radio that I don't know and everyone else seems to think it is iconic.

  • @Kristine.baltazar
    @Kristine.baltazar 8 ปีที่แล้ว

    These videos are so helpful and save so much time!

  • @flamedragon07
    @flamedragon07 4 ปีที่แล้ว +1

    Love the Indiana Jones joke they used. Crash Course you're so amazing.

  • @tobymanurung9717
    @tobymanurung9717 8 ปีที่แล้ว +2

    what a helpful video!!! thanks for the knowledge crash course

  • @ozgeozcelik8921
    @ozgeozcelik8921 8 ปีที่แล้ว +4

    Sir Newton, what a fascinating man

  • @frederickleo2748
    @frederickleo2748 8 ปีที่แล้ว +1

    you said in your video on newton's laws that according to newton's first law, an object would remain stationary (or in constant movement) unless acted upon by a force. A moving object that has momentum is moving at a constant velocity and thus has no acceleration, ergo should not be able to exert a force. However, that rolling ball is obviously able to move indiana jones if it collides with him. How is that?

  • @ondlgt2958
    @ondlgt2958 7 ปีที่แล้ว

    i love the way you explain

  • @UkeNooberx333
    @UkeNooberx333 7 ปีที่แล้ว +1

    shoutout to all the AP physics students who think they will understand all the concepts the night before the exam through crash course

  • @whitemamba2049
    @whitemamba2049 8 ปีที่แล้ว +34

    This lady is amazing. Wish she taught at my college. Would have done much better in Calculus and Physics in college and became a scientist instead of a lawyer . . . . plus she's got to be the best looking Physicist I've ever seen :-)

    • @user-nd1lx8co2g
      @user-nd1lx8co2g 6 ปีที่แล้ว +2

      she's reading a script honestly I find her a bit distracting trying to prove a point about female physicists or something. THERE I SAID IT :P

    • @jasonkaufman2385
      @jasonkaufman2385 6 ปีที่แล้ว

      she is ugly

    • @sarahholland5980
      @sarahholland5980 5 ปีที่แล้ว +4

      @@user-nd1lx8co2g So just because a female has a career in STEM, she MUST be proving a point and furthering the feminist agenda instead of just pursuing something she's genuinely passionate about? Good to see misogyny is still alive and well.

    • @user-nd1lx8co2g
      @user-nd1lx8co2g 5 ปีที่แล้ว

      no it's just that everything about this is fake she is reading from a script @@sarahholland5980

    • @sarahholland5980
      @sarahholland5980 5 ปีที่แล้ว +1

      @@user-nd1lx8co2g But when Hank and John read from scripts it's no big deal right? They're not fake just because they're males? Okay, whatever you say.

  • @WarzSchoolchild
    @WarzSchoolchild 7 ปีที่แล้ว

    Linear Momentum and Angular Momentum are very similar both are 'Vector' quantities, except with 'Angular Momentum' the vector is constantly changing, there is only an 'instantaneous' vector at any particular subtended angle of rotation. Sir Isaac Newton was correct about 'Actions and Equal and Opposite Reactions", but only in simple cases. Sometimes the word 'Opposite' can be turned around. For example we have two parallel tracks, each with a truck in linear motion. They both collide simultaneously with two mirror image discs. ...and just like the linear experiment Momentum is conserved by transfer of linear kinetic energy via two mirror image 'Elastic Collisions' into equal 'mirror image' counter-rotational Angular Momentum. ...These discs are equipped with magnetic bounce mechanisms like the trucks, [near 100% elastic bounce] they bounce back and return their 'Angular Momentum; with a third 'magnetic bounce' to the pair of parallel track trucks. The trucks have effectively "Bounced Back", but it will be observed in practice and reality, that there has been no measurable reaction at all. If this experiment is conducted on a small toy boat, the boat will keep going forward with each elastic bounce, but never go backwards. "VECTORS! MATTER" and please never forget that essential face, especially with a' Vector Quantity' like Momentum.

  • @driss1808
    @driss1808 8 ปีที่แล้ว

    So wait, force is the derivative of mass times velocity, a.K.a momentum relative to time. Mind Blown

  • @lowhertzhighspl
    @lowhertzhighspl 5 ปีที่แล้ว +2

    Finally! A video I found an actual use for making legitimate use for TH-cam's slow-down feature rather than only making people sound drunk. 😁

  • @clementinerosette1038
    @clementinerosette1038 5 ปีที่แล้ว +11

    Taking my physics final in like 7 minutes

  • @emmycoffey400
    @emmycoffey400 7 ปีที่แล้ว

    i owe you my life! these videos rock

  • @luchomolinari
    @luchomolinari ปีที่แล้ว

    Hello there! May I know her name? I'm enjoying the course

  • @evandiego2962
    @evandiego2962 7 ปีที่แล้ว +1

    definitely gonna watch all ur vids this saturday lmao

  • @natplanetary
    @natplanetary 6 ปีที่แล้ว

    you have saved my life

  • @benheideveld4617
    @benheideveld4617 5 ปีที่แล้ว

    Unique content! I found no better.

  • @mineshnissanka7139
    @mineshnissanka7139 2 ปีที่แล้ว +2

    Indiana Jones died just so we could learn about momentum. We must ace our physics tests to not let his death go in vain

  • @Staciabailey14
    @Staciabailey14 8 ปีที่แล้ว

    This might save my GPA thank you so much!!

  • @nadianadeem8528
    @nadianadeem8528 6 ปีที่แล้ว

    her voice is so perfect

  • @camilleandrea9262
    @camilleandrea9262 4 ปีที่แล้ว +1

    What's the difference between momentum and inertia?

  • @jeromeeuler168
    @jeromeeuler168 8 ปีที่แล้ว +1

    awesome episode!!!Very informative

  • @teedentitudie9330
    @teedentitudie9330 4 ปีที่แล้ว +1

    i like her! she does a good job, plus she is funny.

  • @fernandomaron
    @fernandomaron 7 ปีที่แล้ว

    thank you for the video!

  • @davidojo68
    @davidojo68 7 ปีที่แล้ว

    great app

  • @camerondees4440
    @camerondees4440 7 ปีที่แล้ว

    hey thank you so much this video really helped me out!

  • @daninja265
    @daninja265 8 ปีที่แล้ว

    Wish this had come out before my GCSE Physics exams.

  • @cavewallmedia
    @cavewallmedia 8 ปีที่แล้ว

    Helpfull video, thanks for your work

  • @victormaxwellpeters9771
    @victormaxwellpeters9771 4 ปีที่แล้ว

    Dear Madam,
    There is a question which is iching my taughts since many days, that why speed of sound is constant??? Even though sound propagate by means of elastic collisions between molecules, speed of sound should depend upon the speed of molecules near the source of sound. Yes I have heard it already that molecule speed is directly proportion with the increase in pressure so the bulks module remains constant and hence the formula holds. But why then same phenomena is not observed in collision of two identical elastic balls, were the velocity of second ball depends upon the velocity of the first ball and hence the velocity of propagation of this collision also depended on the velocity of first.

  • @mr.thophombenge492
    @mr.thophombenge492 5 ปีที่แล้ว

    up to the par

  • @VyvienneEaux
    @VyvienneEaux 4 ปีที่แล้ว +1

    Is kinetic energy derived from the integral of momentum? 1/2 V^2 looks like an antiderivitive.

  • @jlowe5589
    @jlowe5589 7 ปีที่แล้ว

    Love u Crash course!

  • @GAVISIONI
    @GAVISIONI 8 ปีที่แล้ว +2

    Teachings technique is awesome

  • @leaselmary_sims2189
    @leaselmary_sims2189 8 ปีที่แล้ว +3

    In Russian momentum is called "impulse" and "impulse" is called "force impulse". It got me confused at the beginning, because every time I hear "impulse" I think of the momentum.

  • @MrBuddy5671
    @MrBuddy5671 8 ปีที่แล้ว +1

    I want to see a crash course series on computer programming

  • @cristianrueda2055
    @cristianrueda2055 7 ปีที่แล้ว +1

    I really love you :3

  • @pankhudisaraswat2445
    @pankhudisaraswat2445 7 ปีที่แล้ว

    thanks

  • @swisstraeng
    @swisstraeng 8 ปีที่แล้ว

    Like before watching, anyway we can only love physic!

  • @NickDeBusk
    @NickDeBusk 8 ปีที่แล้ว

    love it. thanks

  • @arwacloud2736
    @arwacloud2736 8 ปีที่แล้ว

    Can't wait for mechanical waves

  • @sophiepeen2307
    @sophiepeen2307 8 ปีที่แล้ว +2

    Can anybody please explain the math at 2:37? :)

  • @unknownpawner1994
    @unknownpawner1994 8 ปีที่แล้ว

    Things are gonna spin right round baby right round like a record baby right round round round next week

  • @Pfhorrest
    @Pfhorrest 8 ปีที่แล้ว +1

    Something's a little off here. She says impulse is change in momentum over time, but that would be mv/t, which is the same thing as ma, which is just force. Impulse is mv/t^2, or ma/t, or force per time.

    • @Rhaegar19
      @Rhaegar19 8 ปีที่แล้ว +1

      Impulse is *just* change in momentum, and it's force*time. It has the same units as momentum (kg*m/s). It's the amount of momentum lost or gained.
      *Force* is change in momentum over time (kg*m/s^2)

    • @Pfhorrest
      @Pfhorrest 8 ปีที่แล้ว

      You're right, I was confusing impulse with jerk, which is acceleration per time. Force per time is equal to mass times jerk, and may or may not be called yank; I can't find a reliable source confirming that.

  • @Hecatonicosachoron
    @Hecatonicosachoron 8 ปีที่แล้ว

    I actually find it easier to say that the centre of mass is the first moment of the mass distribution.
    Momentum is not conserved in systems with drag (or other forms of friction).
    Not to mention that in the examples with the magnets, they will accelerate towards each other and even then you will not have conservation of momentum. Even if one is inclined to perform this little experiment it will be quickly realised that the magnetic bead pair will most likely start spinning after it comes together.

    • @Hecatonicosachoron
      @Hecatonicosachoron 8 ปีที่แล้ว

      lol

    • @GumbootMan
      @GumbootMan 8 ปีที่แล้ว

      Momentum is conserved in systems with drag -- the momentum is simply transferred to the thing doing the dragging. If you're talking about air resistance, then momentum is transferred from the moving object to the air. If you're talking about friction, then the momentum is transferred from the moving object to the surface which is creating the friction. Often the momentum will end up getting transferred to the Earth, which will result in the momentum apparently disappearing -- but it hasn't disappeared, it's just that the Earth's mass is so large that any resulting velocity change is minuscule.

    • @Hecatonicosachoron
      @Hecatonicosachoron 8 ปีที่แล้ว

      If the position of a body moving in a medium is monitored then momentum is not conserved, categorically.
      Furthermore momentum doesn't have to be conserved in situations where you do not have spatial translation symmetry. In addition to non conservative systems as noted above.
      In short to force momentum conservation you have to redefine the 'system' to include much more than one might have originally intended.
      The case is still true for interacting particles, where momentum is, simply, not conserved.

    • @GumbootMan
      @GumbootMan 8 ปีที่แล้ว

      Jason93609
      You are being misleading. When physicists say that momentum is conserved, they mean it is conserved in a closed system i.e. where there are no interactions between your system and the outside world. This is *always* true, from the scale of galaxies, right down to sub-atomic particles. There are no known exceptions to this rule. You are talking about open systems, where the changes in momentum are not being wholly accounted for -- momentum is not conserved in that case, but then no-one ever claimed it was. (This holds true for energy too -- it is only conserved in a closed system.)

    • @Hecatonicosachoron
      @Hecatonicosachoron 8 ปีที่แล้ว

      "Closed" systems are very special! And not the most relevant as well.

  • @nishkakumar8872
    @nishkakumar8872 5 ปีที่แล้ว

    Why would velocity get halved as mass doubles in the magnet example? Mass and velocity are directly proportional?

  • @raphaelbresselsmith5954
    @raphaelbresselsmith5954 8 ปีที่แล้ว

    At 6:00 she states that the momentum is conserved but some kinetic energy is lost because the now stuck together magnets are traveling slower than the single magnet. Where did the kinetic energy go? I thought this was a perfectly inelastic collision in which--theoretically speaking--no energy is lost to thermal energy. If momentum is perfectly conserved, isn't kinetic energy also conserved since it equals 0.5mv^2? Am I misunderstanding something? Great video overall, thanks for posting!

    • @Morelloforever
      @Morelloforever 8 ปีที่แล้ว

      Energy and momentum are different quantities! Momentum will always be conserved, whereas (kinetic) energy will often be lost. I understand your confusion though; the equations for momentum and kinetic energy look similar.

    • @Rhaegar19
      @Rhaegar19 8 ปีที่แล้ว

      In elastic collisions, no energy is lost. In inelastic collisions, energy is *always* lost. For the magnets, most of that is sound, but also some heat. The mass goes up, the velocity goes down, and the momentum (mv) balances out, but energy weights velocity disproportionately (.5mv^2), so it's lost.