Julius Sumner Miller: Lesson 8 - Adventures with Bernoulli

00:14:37
https://www.youtube.com/watch?v=7XHohWDIUB0

概要

TLDRLa vidéo présentée par Julia Su Miller explore le principe de Bernoulli, qui décrit comment la vitesse et la pression d'un fluide en mouvement changent lorsqu'il traverse une constriction. Elle utilise des démonstrations amusantes et instructives pour illustrer comment ce principe explique des phénomènes communs tels que le vol des avions, le fonctionnement des atomiseurs, le tirage des cheminées, et même le comportement des navires passant trop près les uns des autres. Julia partage également comment ce principe joue un rôle dans des incidents réels, comme l'effondrement d'un pont et la conception de trains à grande vitesse. Elle encourage les spectateurs à lire plus sur la famille Bernoulli, des génies renommés pour leurs contributions à la science.

収穫

  • 🎓 Les Bernoulli étaient une famille de génies scientifiques.
  • 💨 Un fluide se déplaçant à travers une constriction augmente en vitesse.
  • 📉 La pression diminue dans une constriction selon Bernoulli.
  • ✈️ Le vol des avions peut s'expliquer par ce principe.
  • 🚢 Les navires risquent de collisionner en raison de la réduction de pression.
  • 🏠 Les cheminées ont un meilleur tirage grâce à Bernoulli.
  • 🚩 Les drapeaux flottent en raison de la pression différenciée.
  • 🚂 Bernoulli a influencé la conception des trains à grande vitesse.
  • 💦 Les atomiseurs fonctionnent sur le principe de Bernoulli.
  • 🏗️ Bernoulli a causé l'effondrement d'un pont par des oscillations.

タイムライン

  • 00:00:00 - 00:05:00

    Julia Su Miller présente le principe de Bernoulli, une famille de génies constituée de 120 membres. Le principe explique que lorsqu'un fluide en mouvement, tel que l'air, traverse un rétrécissement, sa vitesse augmente tandis que la pression diminue. Elle démontre ce principe à travers une série d'expériences : les ailes d'un avion, les balles de croquet et les cheminées sont quelques exemples où l'augmentation de la vitesse et la diminution de la pression se manifestent. Par exemple, en soufflant sur des pages courbées d'un magazine ou entre deux sphères, la pression diminue au point de contact, causant la levée ou l'attraction due à la pression atmosphérique environnante.

  • 00:05:00 - 00:14:37

    Elle poursuit avec des expériences démontrant l'effet Bernoulli : un entonnoir avec du riz soufflé et une balle de ping-pong montrent comment une vitesse de l'air élevée entraîne une réduction de pression, l'air environnant maintenant les objets en place. Un atomiseur utilise le même principe pour pulvériser des liquides. Elle montre aussi comment une boîte en métal peut être comprimée par la pression atmosphérique lorsque la pression intérieure diminue. Pour finir, elle démontre avec une voiture jouet comment le flux d'air maintient une balle en équilibre, illustrant l'importance des applications de Bernoulli dans la vie quotidienne, comme lors du passage de navires ou de voitures à grande vitesse provoquant une réduction de la pression.

マインドマップ

Mind Map

よくある質問

  • Qui était Bernoulli ?

    Les Bernoulli étaient une famille de génies, avec plus de 120 membres remarquables dans l'histoire des sciences.

  • Quel est le principe de Bernoulli ?

    Le principe de Bernoulli explique que lorsqu'un fluide en mouvement traverse une constriction, sa vitesse augmente et sa pression diminue.

  • Pourquoi une aile d'avion peut-elle voler selon Bernoulli ?

    L'air traversant le dessus de l'aile réduit la pression, permettant à la pression atmosphérique en dessous de soulever l'aile.

  • Comment fonctionne un atomiseur basé sur le principe de Bernoulli ?

    L'air passant à travers la constriction dans un atomiseur diminue la pression, forçant le liquide vers le haut et le dispersant en aérosol.

  • Pourquoi les navires ne doivent pas passer trop près les uns des autres ?

    La réduction de pression entre les navires pourrait les pousser dangereusement l'un vers l'autre.

  • Quel effet Bernoulli a-t-il sur les cheminées ?

    Un vent fort au sommet d'une cheminée réduit la pression, améliorant le tirage en poussant la fumée vers le haut.

  • Pourquoi un drapeau flotte-t-il ?

    Le vent réduit la pression sur un côté du drapeau, permettant à l'air de faire flotter et osciller le drapeau.

  • Comment Bernoulli a-t-il causé l'effondrement d'un pont ?

    L'effet Bernoulli a provoqué des oscillations dues à la réduction de pression, entraînant l'effondrement.

  • Quelle est l'utilisation du principe de Bernoulli dans la conception ferroviaire ?

    Lors de la conception du train rapide du Japon, il a fallu considérer l'effet Bernoulli pour la stabilité des voitures.

  • Quels objets peuvent démontrer le principe de Bernoulli ?

    Des balles de ping-pong, des cheminées, des boîtes de conserve et des voitures-jouets peuvent tous illustrer ce principe.

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    [Music]
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    how do you do ladies and gentlemen and
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    boys and girls I am juliia Su Miller and
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    physics is my business and my business
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    today has most uncommon enchantment and
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    of all the things I like to do of which
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    there are hundreds in this business of
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    demonstrations this indeed enchants my
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    soul the most it has to do with the
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    principle of beri beri b e r n o u l l i
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    and I urge you to go and read about the
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    bruli because they were an uncommon
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    family a 100 20 of them all
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    Geniuses unlike anything in the history
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    of the humankind the best that we've
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    ever had are the Box in music and there
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    were only at most 24 of those but can
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    you imagine over a hundred people named
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    beri all Geniuses not one an ordinary
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    man now I will recite to you quickly and
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    passingly the principles lying here in
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    these
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    demonstrations which you can read about
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    in your books first we learn from beri
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    that when a moving fluid like air
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    encounters a constriction that is a
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    narrow space the velocity increases so
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    as we say the velocity is increased in a
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    constriction one other principle emerges
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    from a study of beri and that is that
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    the pressure in a constriction
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    diminishes diminishes or goes down
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    so we have these two principles velocity
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    increases pressure diminishes in a
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    constriction and now I'm going to show
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    you an abundance an array of experiments
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    demonstrations that reveal this consider
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    the following why an airplane can fly
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    says Beni he explains why why a ball can
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    be thrown in a curve why a chimney has a
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    good draft why a bird can
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    soar uh why a boomerang uh whatever it
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    does boomerangs all of these things can
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    be accounted for in terms of beni's
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    principle here is a magazine opened so
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    that the pages are curved in this way
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    and now I am going to blow a stream of
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    air against the inner edge of these
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    pages one would think that they would be
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    pushed down by the push of the air but
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    no watch
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    watch
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    well the page was lifted up there it is
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    now that airplane wing has some flutter
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    which we don't want of course in the
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    real airplane wing but the air going
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    over the top gave rise to a diminution
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    and pressure and the atmosphere below
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    lifted the page up consider another of
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    the same here are two spheres two
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    croquet balls with a little separation
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    between them and this region is a
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    constriction I'm going to blow some air
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    through there
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    one would think impulsively that the
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    Spheres will be blown apart no they are
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    not the pressure will be reduced and the
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    atmosphere will push them together watch
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    it there they are pushed together by the
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    greater atmospheric pressure on the
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    outside now of what consequence is this
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    well very important indeed because if
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    two ships pass let us say two ships
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    passing on the sea if they pass too
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    close to one another the pressure is
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    reduced between them and they could be
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    made to collide and and and break
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    apart here is
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    another very dramatic my chimney effect
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    here I have a chimney you remember a
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    requirement of our work together is
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    Imagination so I could of course draw
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    the picture of my house and my chimney
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    and there's the fireplace in my house
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    now why does my chimney have a good
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    draft it has a good draft if there is a
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    stout wind blowing across the top of the
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    chimney why because high velocity
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    diminution and pressure the atmosphere
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    atmospheric pressure pushes the smoke up
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    the chimney I'm going to prove that here
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    is my fireplace my fireplace is a vessel
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    with some puffed rice here is the
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    chimney I'm going to blow a sharp stream
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    of air across the top the pressure will
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    be reduced here in this region the
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    reduction and pressure will be felt in
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    the tube and the atmosphere will push it
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    up watch
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    it there it is my chimney has an
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    extraordinarily good draft watch it
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    there it is I say that's a terrific
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    chimney now here's one that's even
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    better still here's a funnel and I'm
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    going to put some puffed rice in that
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    funnel and then I'm going to blow some
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    air through that funnel just to show you
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    that air is blowing out of that funnel
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    watch it now well oh well of course
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    there it is sure the puff rice couldn't
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    have come out unless I blew it out now
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    I'm going to put a pingpong ball in
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    there there it is now I'm going to blow
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    that pingpong ball
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    out watch
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    it
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    indeed somebody says oh he's got it
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    stuck in there by magnets or something
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    no no I will dispose of it as quickly as
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    I can with the following remark here it
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    is here it is here is the
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    funnel there is the ball here is the air
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    the ball fits in the funnel very snugly
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    and these regions right here are
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    constrictions and when the air passes in
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    there it has a high velocity and a
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    reduction in pressure and the atmosphere
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    holds the ball
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    up indeed this principle of granuli is
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    why an atomizer works you know what an
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    atomizer is an atomizer is a tube that's
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    resides in a vessel and here is some
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    liquid and here is a tube across here
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    and here is a bulb and you squeeze the
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    bulb air rushes across there is a
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    reduction in pressure the atmosphere
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    pushes the liquid up and then the liquid
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    is caught in the airst Stream and comes
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    out there I have often thought that the
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    reason that's called an atomizer is
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    because little atoms of the liquid come
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    out there don't you like that idea
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    little atoms now here is an
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    atomizer and spray would come out there
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    now I'm going to show you an atomizer on
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    large scale watch it this is
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    fantastic here is a tin can and here is
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    a tube quite like that one residing in
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    the atomizer and I'm going to blow a
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    stream of air through this tube there
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    will be a reduction of pressure in the
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    tin can and now what will the atmosphere
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    do
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    if the can has less pressure inside the
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    atmosphere will collapse it because it
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    is enormously strong watch it
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    watch there it is there it is I tell you
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    that's terrific it's so terrific I'm
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    going to do it again with another one
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    there's another one yeah why well if I
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    like it I'm going to do it twice I may
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    do it three four times watch
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    it oh look at that well that's two times
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    and I'm going to do it once more once
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    more why because I like it
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    watch oh oh there it is notice notice
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    there it is wait there it
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    is there it is and I tell you that's
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    terrific that's
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    fantastic
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    now pressure reduced in the
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    construction velocity
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    increased consider
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    a
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    consequence
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    flag United States flag Australian
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    flag why does a flag flutter
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    beri have you not heard sometimes your
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    Venetian
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    blinds chatter beri the air blowing
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    across the top of the shutter gives rise
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    to a reduction in pressure the shutter
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    is lifted up now because of its
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    springness and its inertia it falls back
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    and so it oscillates and I'll tell you
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    how powerful an instrument Bern's
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    principal is some years ago a bridge way
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    up in Northern Washington collapsed
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    because of the effect of berly's
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    principle because of the role beri
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    played now we got something wonderful
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    terrific oh why is it terrific because
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    you would not believe it here it is
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    suppos and I had a tool Tu and I drove a
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    stream of air up here and I had a ball
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    right at the top vertically above the
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    blowing air you would say if the ball
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    stays there it's because the air pushes
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    up and the ball pushes down and when
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    they are equal the ball stays there and
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    that would be correct but now supposing
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    I turn the tube off the vertical and the
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    ball still stayed there well you can't
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    say that anymore because when the ball
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    receives the air that way there is a
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    component that way and a component that
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    way that one may hold up the ball but
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    this one should drive it away but I'm
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    going to show you that it doesn't watch
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    it oh little
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    trouble uhoh let me try a heavier ball a
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    golf
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    ball
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    [Music]
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    and I call to your attention a very
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    significant feature of this the ball was
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    spinning this spin gave rise to a
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    reduction of pressure on the upper side
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    whereupon the atmosphere held it up
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    let's take a big one like this
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    and I say that's terrific I just love
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    that I want to do it again because I
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    do any objections
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    notwithstanding question could I get
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    that ball on the horizontal that's a
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    good one to explore indeed you can do
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    this by going to your gasoline station
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    and using the air holes At Your Service
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    Station uh let me do it again with a
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    golf ball which is quite heavy golf ball
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    quite
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    heavy oop little
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    trouble now
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    finally since I enjoy as you know the
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    physics in toys here is a wonderful
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    demonstration of beri here is a little
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    toy car here is a little toy car and
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    what am I doing I am storing some energy
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    in a wound up Spring and when I release
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    the
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    spring it unwinds and turns a fan and
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    there is a stream of air emerging from
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    here I'm going to show you that there is
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    watch it there is a little polystyrene
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    ball there it is
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    now remember I can put that off the
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    vertical watch
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    it there it is now what I'm going to do
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    should be an enchantment for ages 4 to
  • 00:12:43
    94 as all the physics that we do should
  • 00:12:46
    be watch it now
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    watch oh is that
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    do look at
  • 00:12:54
    that I want to do that again cuz I like
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    it
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    there it
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    is this is a beri car and why does it
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    work as it does because one there is a
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    push of the air a high velocity on one
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    side of the ball which gives rise to a
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    diminution and pressure and
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    thereby the atmospheric below holds it
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    up
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    now what shall we say about bruli the
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    applications are phenomenal as I Remar
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    two ships passing uh on the sea should
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    not pass too close to each other indeed
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    have you not stood on the sidewalk when
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    a fast moving vehicle has gone by and
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    you have been made to rock or have you
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    not passed in your car a bus let us say
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    and your car is made to rock this is a
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    consequence of the reduction in pressure
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    between the vehicles where upon the
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    atmosphere on the outside pushes them
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    together indeed when the Japanese design
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    their most recently uh accomplished
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    railroad from Osaka to Tokyo where the
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    trains go about 120 M an hour what was
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    the critical thing several one the
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    center of gravity idea number two how
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    close can the cars be without the effect
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    of beri and so I say read about the beri
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    they are wonderful to know about and I
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    thank you for your
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    attention
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    [Music]
タグ
  • Bernoulli
  • physique
  • fluide
  • démonstration
  • pression
  • vitesse
  • constriction
  • avion
  • atomiseur
  • pont