Viscosity and Poiseuille flow | Fluids | Physics | Khan Academy

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  • čas přidán 31. 08. 2014
  • David explains the concept of viscosity, viscous force, and Poiseuille's law.
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Komentáře • 71

  • @jaymayhoi
    @jaymayhoi Před 9 lety +63

    Attempting to learn fluid dynamics and this is awesome, thanks. Makes me ponder how far reaching studying medicine is

    • @user-kb7oe5wr7c
      @user-kb7oe5wr7c Před 7 lety +13

      In the exact same place right now, our textbooks are complete shit, but thanks to this I just started understanding it.

  • @ShadeOtree
    @ShadeOtree Před 7 lety +43

    الله يدخلك الجنه من أوسع ابوابها
    there are doctors gain more than 300 SR (nearly 80$ ) to teach us for an hour what you said in this video ! Thank you so much

  • @s5960
    @s5960 Před 9 lety +10

    Brilliant, no idea why this video has so little views

  • @theDeathJoy
    @theDeathJoy Před 3 lety +2

    This explanation saved me where teachers failed. They keep redirecting me to formulas that are of no use and refuse to give a greater in depth explaination... So sad that college tuition is being wasted like that.

  • @heiheihei60
    @heiheihei60 Před 6 lety +1

    The explanation is so clear, and interesting

  • @mahimapasricha6388
    @mahimapasricha6388 Před 5 lety +5

    I m in love with your teaching.. U taught so nicely thanks.
    ~a new fan and subscriber

  • @majdal-awar752
    @majdal-awar752 Před 2 lety +1

    Amazingly explained!

  • @alialobaidy4610
    @alialobaidy4610 Před 5 lety +4

    I will name my first born after you.
    Also, someone just prayed for you to go to paradise in Arabic. This video literally creates world peace!

  • @yuta2349
    @yuta2349 Před 4 lety +1

    This was really helpful. Well explained :)

  • @taylorneill2687
    @taylorneill2687 Před 5 lety

    Amazing video, best Ive found thanks

  • @anshulbirwal5788
    @anshulbirwal5788 Před 5 lety +2

    It helped me a lot ✌

  • @zamramumthaz1428
    @zamramumthaz1428 Před 6 lety

    Incomparable explanations awsome.....

  • @user-le2wu4yl7w
    @user-le2wu4yl7w Před 3 lety

    Very good example and explanation for understanding. Thank you

  • @abdulmuizadegbindin3520
    @abdulmuizadegbindin3520 Před 7 lety +4

    excellent video

  • @antalenej3885
    @antalenej3885 Před 2 lety

    Thank you for this amazing video helped me a lot ❤

  • @2175Wook
    @2175Wook Před 7 lety +6

    A Fluid Mechanics problem that I'm trying to work out. A viscometer of the Redwood type has an oil-containing cylinder 4.75cm in diam and an agate tube 0.17 cm in diameter and 1.2 cm long. The oil surface, when flow starts, is 9 cm above the outlet from the agate tube. To allow for the sudden contractions at entry to the tube, the effective length of the tube may be taken as the actual length plus the tube radius. Making allowance for the decreasing head of oil, the viscous resistance through the tube, and the KE (kinetic energy) of discharge, calculate using arithmetical integration, the time required for 50 cm3 of an oil of viscosity 0.5 poise and specific gravity 0.92 to flow through the viscometer. How do you find the time? From this question, I have tried to use quadratic equation to solve for v, but it is proving more difficult than I thought

  • @sushanchamrugurung229
    @sushanchamrugurung229 Před 7 lety +19

    it's awesome ..... better than textbooks

    • @ruirodrigues3596
      @ruirodrigues3596 Před 7 lety +1

      ofc its better than textbooks thats why teachers exits. Now the majority of uni teachers are people without the gift of education and with 3 phds so they tend to complicate even the most simple shit.

    • @kimanhoanthi117
      @kimanhoanthi117 Před 4 lety

      literally. i couldnt understand a thing from my textbook so I had to come here.

  • @abhinavpa7688
    @abhinavpa7688 Před 5 lety +1

    Very helpful thanks😍

  • @yazandouleh9088
    @yazandouleh9088 Před 7 měsíci

    Highly appreciated, thank you so much

  • @salmagamal5676
    @salmagamal5676 Před 5 lety

    LIFE SAVER
    as always

  • @OiynsoftCorporation
    @OiynsoftCorporation Před 5 lety +7

    10:50 draws that smile 😂

  • @bohdansenchyshyn9598
    @bohdansenchyshyn9598 Před 5 lety +1

    Nice. Excellent!!!

  • @xxxx-xs5vr
    @xxxx-xs5vr Před 7 lety

    you are amazing thank u so much

  • @deviprasadpandey8518
    @deviprasadpandey8518 Před 2 lety

    Thanku so much sir you and your way of teaching is just amazing

  • @vAman00
    @vAman00 Před 7 lety +5

    I love your way of teaching 😭😭😭😭😭💓

  • @sophmiester
    @sophmiester Před 7 lety

    thats a dope box brah

  • @twominuteanaesthesia
    @twominuteanaesthesia Před měsícem

    Good stuff

  •  Před 4 lety

    perfect.

  • @paoisaacleo882
    @paoisaacleo882 Před 7 měsíci

    Thankyou

  • @Kencan254
    @Kencan254 Před 6 lety

    In MCAT, is the Poiseuille formula provided?

  • @skilifavas4016
    @skilifavas4016 Před 5 lety

    Someone give this guy Money

  • @debangana9964
    @debangana9964 Před 7 lety +36

    This guy, whoever he is, is great 😂😂😂

  • @dhruvparmar4061
    @dhruvparmar4061 Před 2 lety

    How we can consider fluid that is in contact with pipe is stationary?

  • @dontarobta4439
    @dontarobta4439 Před 6 lety +1

    Whats the formula for viscosity in a newtonian fluid?? How do we "ignore" the "v" thats already present in the formula???

    • @saramohamed.8403
      @saramohamed.8403 Před 3 lety

      Try watching "why is ketchup so hard to pour" by TED ... it is kinda helpful with this speed matter

  • @ashu.tosh_kumar11
    @ashu.tosh_kumar11 Před 4 lety +1

    Please can you write back me or give me ling of this question 👉on the view of viscosity and type of flow explane flood

  • @RhodesW
    @RhodesW Před 6 lety +20

    If you play it on 2x speed the mannerisms of speech sound like Rick from Rick and Morty

  • @leeeeni
    @leeeeni Před 3 lety

    Is the first flow called Couette-flow?

  • @ushasri2462
    @ushasri2462 Před 6 lety

    why did u consider velocity as speed in unit? Only that portion is not understood..same thing done in the book.

  • @faizagha2362
    @faizagha2362 Před 6 lety +1

    Wouldn't the viscous force be equal to the force applied because Newton said opposite and equal reaction to an action?
    Please can someone explain me that why can't we just say that the viscous force is equal to the force applied to the lid.

    • @faizagha2362
      @faizagha2362 Před 6 lety +1

      And please if I have left some basics don't mock me just answer me

    • @Drew88317
      @Drew88317 Před 6 lety

      Equal and opposite reactions wouldn't resign every action to inaction, that is to say things can still move and not be stopped by the so called opposite force. Assuming the edges of the box were frictionless you could determine to a decent degree the viscosity by applying an increasing force to the plank and seeing at what point it began to move. If we do in fact know the coefficient of friction between the edges and the plank then we can estimate the viscosity by looking at the rate of deceleration when the box is full and when it is empty. The opposite force in this case is that the water pushes back, but more of the water will be pushed forward in the plank's direction.
      TLDR: We know the forces aren't equal because the plank is moving. The breaking point between where it begins to move and is stationary would be an equal force to the viscosity.

  • @MikeSmith-ej4zv
    @MikeSmith-ej4zv Před 6 lety +2

    How would n not depend on velocity when n=f*d/A*v?

    • @davidkippy101
      @davidkippy101 Před 6 lety

      Mike Smith Because F is also in the equation, and when v changes, so does the force, which compensates for the change in velocity.

    • @nicholasturo-shields6477
      @nicholasturo-shields6477 Před 6 lety

      The viscosity is generally a material property, depending on the temperature and other relevant state factors. Whether you pull fast or slowly does not change this material property. (This is only true for Newtonian fluids. Non-newtonian fluids act differently and are really cool. I suggest you look up videos on them)

    • @saramohamed.8403
      @saramohamed.8403 Před 3 lety

      Try watching "why is ketchup so hard to pour" by TED it explained this speed thing

  • @sahubabu5267
    @sahubabu5267 Před 2 lety

    Soothing accent

  • @abhinav3478
    @abhinav3478 Před 6 lety

    Is unit of coefficient of viscocity is
    Kg/ms ?
    F = n A v/d
    n = Fd/Av
    = kg m s^-2 * m / m^2 * m s^-1
    = kg m^-1 s^-1

    • @nicholasturo-shields6477
      @nicholasturo-shields6477 Před 6 lety

      This is also an acceptable unit for viscosity coefficient, yes (see en.wikipedia.org/wiki/Viscosity). -Engineering student at Purdue

  • @tecnicaltecnical4356
    @tecnicaltecnical4356 Před 7 měsíci

    There isnt in your videos translated in turkish can you add?

  • @niko-ni6ps
    @niko-ni6ps Před 4 lety +3

    Keep scrolling guys, I just randomly watched this at 3 a.m

  • @bytheway1031
    @bytheway1031 Před 2 lety

    🎂Jean Poiseuille 04-22-2022

  • @leeeeni
    @leeeeni Před 3 lety

    Poise is not longer allowed as unit for viscosity.

  • @BobProductions
    @BobProductions Před 3 lety

    Why is P not cP??? When it’s 1/10th of Pa*s ???????

  • @tecnicaltecnical4356
    @tecnicaltecnical4356 Před 7 měsíci

    Can you add subtitle in turkish.because I wanna improve my English

  • @thomasweyermann5848
    @thomasweyermann5848 Před 4 lety

    3:14 what I know you’re all here for

    • @fernandb.6162
      @fernandb.6162 Před 3 lety +1

      Thanks man.
      "What is a viscous fluid ?"
      It's *T H I C C K*

  • @aryazephyrnavin761
    @aryazephyrnavin761 Před 3 lety

    check out this empty box! now check out this lid I can put on empty box!

  • @sisyphus645
    @sisyphus645 Před 3 lety

    Wait...You're not Sal (but just as cool)

  • @saraemad7238
    @saraemad7238 Před 2 lety

    Plz add Arabic language in subtitles 🙏🗣️