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

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  • Опубликовано: 21 июл 2024
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    In this video David explains some of the common misconceptions in dealing with Newton's Third Law. He also shows how to correctly and reliably identify Third Law force pairs.
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Комментарии • 74

  • @simranjoharle4220
    @simranjoharle4220 6 лет назад +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 лет назад +2

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

  • @johnfox9169
    @johnfox9169 10 месяцев назад +4

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

  • @asadraza3149
    @asadraza3149 6 лет назад +11

    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.

  • @mojo6689
    @mojo6689 7 лет назад +56

    i feel so smart right now

  • @AdamTheWeeb
    @AdamTheWeeb Год назад +4

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

  • @afsheentahira3241
    @afsheentahira3241 3 года назад +3

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

  • @subhasissarkar1357
    @subhasissarkar1357 4 года назад +6

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

  • @chenchuanshui6858
    @chenchuanshui6858 6 лет назад +7

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

  • @aditimitra8040
    @aditimitra8040 5 месяцев назад +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?

  • @frankivinstutoring3775
    @frankivinstutoring3775 Год назад +1

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

  • @fzka_
    @fzka_ 4 года назад +2

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

  • @agent-sz2qj
    @agent-sz2qj 7 лет назад

    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 ?

  • @ruanoosthuizen6084
    @ruanoosthuizen6084 4 года назад +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?

  • @mustafar
    @mustafar 5 лет назад +3

    David explains really well!

  • @YusufKhan-ec8hj
    @YusufKhan-ec8hj 2 года назад +1

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

  • @feranmiadeyemo2362
    @feranmiadeyemo2362 7 лет назад +10

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

  • @jfhameem1532
    @jfhameem1532 3 года назад +1

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

  • @geeksahilthakur
    @geeksahilthakur 2 года назад

    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 ?

  • @leos9682
    @leos9682 2 года назад

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

  • @ppscphysicspreparation2626
    @ppscphysicspreparation2626 5 лет назад

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

  • @lychee4031
    @lychee4031 2 года назад

    thank you for the clarifications!

  • @thxdts1999
    @thxdts1999 8 лет назад

    Many thanks for the video very pertinent

  • @mdhassanjahangirkhan5756
    @mdhassanjahangirkhan5756 2 года назад +1

    Best explanation ever I got

  • @lizarose3095
    @lizarose3095 6 лет назад +2

    Fantastic video!

  • @Kanari152
    @Kanari152 7 лет назад +1

    THANK YOU VERY MUCH!

  • @iwishifiwasaneconomicsnerd9648
    @iwishifiwasaneconomicsnerd9648 4 года назад

    good explanation.

  • @Talentist-if4ge
    @Talentist-if4ge Год назад

    The MOST underrated channel of the decade

  • @huntergirl7275
    @huntergirl7275 5 лет назад +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))?

    • @user-eo9ye6iv3j
      @user-eo9ye6iv3j 4 года назад +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 Год назад

      @@user-eo9ye6iv3j 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

  • @ranjanchauhan4455
    @ranjanchauhan4455 4 года назад

    Great..

  • @danielsengal8431
    @danielsengal8431 3 года назад

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

  • @sharonsolana
    @sharonsolana 3 года назад

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

  • @agent-sz2qj
    @agent-sz2qj 7 лет назад +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 лет назад

      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 лет назад

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

    • @YaserSamin
      @YaserSamin 7 лет назад +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 5 лет назад

      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 5 лет назад

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

  • @kategothberg4976
    @kategothberg4976 4 года назад

    God bless you my man

  • @THEMATT222
    @THEMATT222 4 года назад +3

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

    • @THEMATT222
      @THEMATT222 3 года назад

      @Moon Deccans yeah, lol

  • @sanjakader9011
    @sanjakader9011 7 лет назад

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

  • @phenomenalphysics3548
    @phenomenalphysics3548 4 года назад +2

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

  • @baskaranbaskaran5283
    @baskaranbaskaran5283 5 лет назад +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 года назад +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 3 года назад +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.

  • @homemadesauce6153
    @homemadesauce6153 3 года назад

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

    • @s.mishra5595
      @s.mishra5595 2 года назад

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

  • @sathibabu9365
    @sathibabu9365 3 года назад +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 года назад

      @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 года назад

      @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

  • @user-dx1ll9kd3w
    @user-dx1ll9kd3w 10 месяцев назад

    0:50 bruuuuh💀💀💀💀

  • @ricaramirez5411
    @ricaramirez5411 7 лет назад

    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 7 лет назад

      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 7 лет назад

      thanks!

  • @Dr.Bright
    @Dr.Bright 4 года назад

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

  • @cyprianjude01
    @cyprianjude01 3 года назад

    Yippee

  • @legendic2755
    @legendic2755 5 лет назад +5

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

  • @weebz4748
    @weebz4748 6 лет назад +1

    David > sal