More on Newton's third law | Forces and Newton's laws of motion | Physics | Khan Academy

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  • Опубліковано 13 гру 2024

КОМЕНТАРІ • 77

  • @simranjoharle4220
    @simranjoharle4220 7 років тому +44

    I always thought that equal and opposite forces should cancel each other out and nothing should ever move if Newton's third law is true....but this doesn't make sense in the practical world so I never believed the law was true until now....tnx a lot

    • @dontblink20
      @dontblink20 6 років тому +2

      Simran Joharle i had that same misconcept and thnx to this video i got it

  • @asadraza3149
    @asadraza3149 7 років тому +12

    Even the most reputed channels for physics confused the problem of weight and normal reaction as an action reaction pair model. Thank you for explaining it so clearly.

  • @johnfox9169
    @johnfox9169 Рік тому +4

    That is the BEST explanation of the third law I ever encountered. Great job and thanks!!

  • @mojo6689
    @mojo6689 8 років тому +57

    i feel so smart right now

  • @aditimitra8040
    @aditimitra8040 10 місяців тому +1

    I have a question. If we push a block lying on a table, we apply an action force on the block. So, the block must also apply an equal and opposite reaction on us. Then, the two forces must cancel each other and there must not be any acceleration. But this doesn't happen. If we push the block too hard then it moves. So how does this happen?

  • @AdamTheWeeb
    @AdamTheWeeb 2 роки тому +4

    This was EXTREMELY helpful. Like you have no idea how helpful. I will probably not fail my physics test today now. Thanks c:

  • @subhasissarkar1357
    @subhasissarkar1357 5 років тому +7

    Thank you so much for clearing our misconception. I had the same misconceptions that were being discussed. Thank you.

  • @chenchuanshui6858
    @chenchuanshui6858 6 років тому +8

    Thank you very much
    You solve my problems that confused me for a very long time

  • @mustafar
    @mustafar 6 років тому +3

    David explains really well!

  • @YusufKhan-ec8hj
    @YusufKhan-ec8hj 3 роки тому +2

    Professor David explaining Newton's laws misconceptions like playing Pacman!! (kudos)

  • @afsheentahira3241
    @afsheentahira3241 3 роки тому +4

    7:34 “this example drives ppl crazy for some reason” LMAO
    (i was at first too lol)

  • @frankivinstutoring3775
    @frankivinstutoring3775 Рік тому +1

    Best explanation of this confustion I've ever seen. Thanks!

  • @feranmiadeyemo2362
    @feranmiadeyemo2362 7 років тому +10

    Wow. I have been enlightened. Thank you so much Professor.

  • @mdhassanjahangirkhan5756
    @mdhassanjahangirkhan5756 3 роки тому +1

    Best explanation ever I got

  • @fzka_
    @fzka_ 4 роки тому +2

    Okay, this answered a lot of my questions regarding to N3L! Thanks to Khan Academy

  • @jfhameem1532
    @jfhameem1532 3 роки тому +1

    why this thing is so cool??...Really loved it.😘

  • @Talentist-if4ge
    @Talentist-if4ge Рік тому

    The MOST underrated channel of the decade

  • @ruanoosthuizen6084
    @ruanoosthuizen6084 4 роки тому +1

    Interesting. So, in sprinting, to sprint faster, how would this theoretically apply? It's obviously not just "put more force knto the ground in the right direction" is it?

  • @huntergirl7275
    @huntergirl7275 6 років тому +2

    I think there is a problem with your box on the table example. How can the box be pushing down on the table (F(subTA)), but pulling up on the earth (F(sub EA))?

    • @ЮлияВиноградова-ю6и
      @ЮлияВиноградова-ю6и 5 років тому +2

      I thought about it for a really long time and watched video three times ). And I realized that there are no mistakes. Earth attracts box A that's why the box need to resist that's why F(sub EA) is pointing up. On the contrary, table doesn't attract box A, but box A pushes down to the table F(subTA). So that's all right.

    • @robertjr8205
      @robertjr8205 Рік тому

      @@ЮлияВиноградова-ю6и yea the box is being brought toward the earth. So it should be the force exerted on Earth by box A rather than the way he wrote it. And the green one should be the force exerted on box A by the Earth. The earth is pushing up against the box. The way he wrote that contradicts the sand example that was done in another video and the wall kicking he did in this video.
      Edit: Nevermind. You are right. My bad. This one bothered me a lot

  • @ธวัชชัยก้อนเพชร-ศ1ห

    0:50 bruuuuh💀💀💀💀

  • @lizarose3095
    @lizarose3095 6 років тому +2

    Fantastic video!

  • @ossabellator13
    @ossabellator13 3 місяці тому

    Thank you for this video. Most clear explanation I've seen.

  • @lychee4031
    @lychee4031 2 роки тому

    thank you for the clarifications!

  • @agent-sz2qj
    @agent-sz2qj 7 років тому +4

    the mass of the earth is approximately 5,972 × 10^24 kg, so if i excert a force of for example 50N on the earth , the earth will have an acceleration of a= F/m = 40N/5,972 × 10^24 kg = 8.372*10^(-24), even though it's a very small acceleration, can i say that i've moved the earth ?

    • @YaserSamin
      @YaserSamin 7 років тому

      the silence breaker Yes you can say you moved the earth but in reality it's not going to move.
      Why it is not going to move? You should know it by now.

    • @agent-sz2qj
      @agent-sz2qj 7 років тому

      because the sun is also exerting a gravitational force on the earth ?

    • @YaserSamin
      @YaserSamin 7 років тому +1

      the silence breaker Let's not make it complicated. The force that you Exerted, the Earth is going to exert the same force on you. Relative to Earth and yourself only, Newton's Third Law is going to act. However, your force won't move the Earth because Earth is a huge body and it's impossible to make it move with such little force
      Only the sun can exert a force and make the Earth Move. Earth exerts the same force on Sun but the sun remains in it's position because of how large it is compared to Earth.

    • @rajanesaki9051
      @rajanesaki9051 6 років тому

      Actually it will move if you are the only organism living alive....or else the will be other people who'll be cancelling out what you've did....from the other side...

    • @legendic2755
      @legendic2755 6 років тому

      why do you want to know if moved the earth just live your life

  • @phenomenalphysics3548
    @phenomenalphysics3548 5 років тому +2

    10:06 but the earth is actually moving toward the object when it falls with respect to object

  • @ppscphysicspreparation2626
    @ppscphysicspreparation2626 5 років тому

    Thnku so much, i was highly confused till i watched this

  • @iwishifiwasaneconomicsnerd9648
    @iwishifiwasaneconomicsnerd9648 4 роки тому

    good explanation.

  • @agent-sz2qj
    @agent-sz2qj 7 років тому

    for example , if i were in space and there is no gravitational force or any other force, and an object with the mass of 0.01 Kg hits me with a force of 0.1N, then i will exert on it an equal opposite force, it's acceleration would be a=F/m= 0.1N/0.01kg =10 m/s^2, is that correct ?

  • @THEMATT222
    @THEMATT222 4 роки тому +3

    So Newton's third law is a scientific version of Karma

    • @THEMATT222
      @THEMATT222 3 роки тому

      @Moon Deccans yeah, lol

  • @leos9682
    @leos9682 3 роки тому

    how does the force of the table itself to the earth affect the box? or does it not matter?

  • @Kanari152
    @Kanari152 8 років тому +1

    THANK YOU VERY MUCH!

  • @geeksahilthakur
    @geeksahilthakur 2 роки тому

    sir we know that F = ma then how will the wall apply force if you kick the wall as you have shown in your example ?

  • @thxdts1999
    @thxdts1999 8 років тому

    Many thanks for the video very pertinent

  • @baskaranbaskaran5283
    @baskaranbaskaran5283 5 років тому +1

    When we drop a object from a certain height from the ground. It strikes the ground but not attained the height of where it dropped .is Newton third law is wrong ? comment about it

    • @ihatetobethatguybut7175
      @ihatetobethatguybut7175 4 роки тому +1

      I think that the "opposite" force doesn't include the Gravitational Force, or maybe it has something to do with Newton's second law, specifically the Mass of an object

    • @malaikashroff7608
      @malaikashroff7608 4 роки тому +1

      That has nothing to do with force. That’s because of energy. The earth has a force on the dropped object (gravity) and the dropped object has a force on earth. That last force doesn’t result in much acceleration by earth Bc earth has a large mass.

  • @DaniilRogers
    @DaniilRogers 3 місяці тому

    This explanation makes a mockery of my high school physics teachers😅😂

  • @ranjanchauhan4455
    @ranjanchauhan4455 4 роки тому

    Great..

  • @sathibabu9365
    @sathibabu9365 3 роки тому +1

    Sir but action and reaction is not equal in the water but you newton told that action is always equal to reaction why ❓

    • @sathibabu9365
      @sathibabu9365 3 роки тому

      @Moon Deccans when I entered into water I am applying a force with my foot but the water not applying same force why

    • @sathibabu9365
      @sathibabu9365 3 роки тому

      @Moon Deccans sir that only l am telling newtons 3rd law has to obey for every action has to be a opposite reaction but water is not showing reaction on mee SO, newtons 3rd is not obey there

  • @sanjakader9011
    @sanjakader9011 7 років тому

    the force on earth by A, pointing up, what force is that?

    • @rabblay9073
      @rabblay9073 7 років тому

      Sanja Kader Normal force.

    • @fionagreen9322
      @fionagreen9322 7 років тому

      its your own personal gravitational force

    • @phenomenalphysics3548
      @phenomenalphysics3548 5 років тому

      @Rimjhim Mitra Exactly! I see them LITERALLY EVERY WHERE!!!!

  • @tonyhill2318
    @tonyhill2318 2 місяці тому

    Holy crap you're beating a simple topic to death

  • @danielsengal8431
    @danielsengal8431 3 роки тому

    I thought I new newtons 3rd law but I didn't, thanks for the up grade

  • @sharonsolana
    @sharonsolana 3 роки тому

    I'm confused. I have to watch this again.

  • @ricaramirez5411
    @ricaramirez5411 8 років тому

    How do you know whether the force is the F(color green) or the -F(violet)? Sorry I'm a bit confused hehe does it matter which is which?

    • @brunoramirez2602
      @brunoramirez2602 8 років тому

      yaeh, it doesn't matter, it just the opposite force. You could call -F(violet) F, and then F(green) would be -F.

    • @ricaramirez5411
      @ricaramirez5411 8 років тому

      thanks!

  • @kategothberg4976
    @kategothberg4976 5 років тому

    God bless you my man

  • @homemadesauce6153
    @homemadesauce6153 3 роки тому

    What about a rocket dou. It's on the same object

    • @s.mishra5595
      @s.mishra5595 2 роки тому

      Maybe like rocket exerts force on the particles and they exert force on the rocket

  • @Dr.Bright
    @Dr.Bright 5 років тому

    at the end of the video a dog barks
    Edit: 13:04

  • @legendic2755
    @legendic2755 6 років тому +5

    I understood nothing, you just made me more confused, I hope sal created this video

  • @weebz4748
    @weebz4748 6 років тому +1

    David > sal

  • @cyprianjude01
    @cyprianjude01 4 роки тому

    Yippee