Bernoulli's principle
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- เผยแพร่เมื่อ 26 พ.ย. 2021
- The narrower the pipe section, the lower the pressure in the liquid or gas flowing through this section. This paradoxical fact, following from the law of conservation of energy, is called the Bernoulli principle or law.
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This principle humbled me as a young scientist and student pilot. I thought I knew everything, that I had an intuitive grasp of basic physics. It took me a long time to wrap my head around this one principle.
Good to hear! We should never assume that we know everything of anything. This video was indeed quite intersting.
It seems to make more sense for me to realize the air being blown is sticky and grabs the air from the side tube and pulls it along. Mayne not correct but hey I'm just a regular joe
Yes, that’s a good way to think of it. It makes more logical sense to me the way you’ve described the ‘sticky air’. I’ll remember that.
This is literally what I study in Highschools. This principle is one of the basics.
Physics is the discipline where math proves common sense totally wrong.
The interesting part is that if you close the system, when you blow, pressure increases. However, when you open so that the air can flow, the pressure decrease the faster it goes.
I've just finished reading James Burke's superb book Connections, which I would recommend to anyone interested in the history of scientific ideas. In this book he explains how this principle was used to create carburettors, making possible the internal combustion engine and jet engines, and how the principle it could be used to measure the flow of a gas through a pipe. However, limited space only allowed him to give a brief overview of these things. The excellent demonstrations in your video make it easy to get my head around these concepts.
The TV series Connections is superb, as well. I highly recommend it.
Great demonstrations of Bernoulli's principle! Seeing the effect in action helps to understand it.
Unfortunatly, it is WRONG. Please make corrections or remove it.
..
The statements about Bernoulli's Principle are correct, but the demonstrations are very poor.
The balls, spoon and funnel are a result of the Coanda effect.
.
The tube inserted into the wall of the neck is protruding into the flow (seen at time 2:57) This causes the air to curve around the end and sides of the tube. This curved flow is the cause of the lowered pressure. This will work with no pipe around it; just the air blowing across the vertical tube.
..
To correctly measure the static pressure inside your narrow neck, the end of hat tube MUST be flush with the inside surface.
..
At time 4:51 we see that the two pressure sensing tubes appear to be more like flush, but it is difficult to see clearly. For that to truly sense the static pressures, there must be NOTHING protruding into and disturbing the flow.
This video is awesome! It explains teh principle in a simple way, as well as showing *how* it works and demonstration of the use
Same thing happens when high-pressure information passes through my low-pressure brain
What, it pushes your balls together? (sorry; couldn't resist)
Beautifully explained. One of the best videos on Bernoulli's principle on TH-cam.
An excellent learning aide. Very well done.
Best explanation of Bernoulli's principle I came across on internet. Thank you so much!!
Comical. EVERY video on this topic has the exact same explanation: "narrower the pipe section, the lower the pressure" because equations . What happens is equations due to more equations . HOW does it work? By equations .
@@billshiff2060 Buddy, the equations explain exactly why this occurs. The velocity of the fluid increases as it travels from a wider region to a narrower region, as the work done by the fluid is down a pressure gradient. Therefore, the fluid must flow from a region of a higher cross-sectional area to a narrow cross-sectional area in order to increase its velocity, and this would naturally cause the pressure exerted by the fluid to decrease. Mathematical equations simply explain this phenomenon through variables instead of words.
@@weltschmerzistofthaufig2440 So your explanation is, it is caused "naturally" + equations.
No mention of particle velocity, which IS the cause of pressure, is ~ mach 1.5 regardless of where it is and yet the pressure decreases in smaller passages.
@@billshiff2060 Are you saying that Bernoulli’s principle doesn’t work? I could use kinetic particle theory to explain it, but I instead focused on macroscopic observations and mathematical evaluation to explain this. Also, who told you that particle velocity remains the same? In fact, in a narrower section, the total number of collisions between particles and the container would decrease as the work done by the fluid occurs in the direction of movement. Thus, a pressure gradient must exist to ensure that there is an increase in kinetic energy in a narrower region.
@@weltschmerzistofthaufig2440 Who told you that particle velocity varies?
Excellent video, thank you for sharing this!!!
What a superb video lesson. Very clear and engaging. Many thanks.
😊
But WRONG.
The statements about Bernoulli's Principle are correct, but the demonstrations are very poor.
The balls, spoon and funnel age a result of the Coanda effect.
.
The tube inserted into the wall of the neck is protruding into the flow (seen at time 2:57) This causes the air to curve around the end and sides of the tube. This curved flow is the cause of the lowered pressure. This will work with no pipe around it; just the air blowing across the vertical tube.
..
To correctly measure the static pressure inside your narrow neck, the end of hat tube MUST be flush with the inside surface.
..
At time 4:51 we see that the two pressure sensing tubes appear to be more like flush, but it is difficult to see clearly. For that to truly sense the static pressures, there must be NOTHING protruding into and disturbing the flow.
You just made a carburetor.
Damb it you beat me to it lmao
And an air brush.
I thought it was a bong. But I ain’t that smart. 😂
Merge collector 😎
Syphon hose
One of the clearest explanations of Bernoulli's Principle that I have seen. Everything very well explained, and many examples showing how everything works. Thank you very much!
Please make more videos. 🙏
Doing so will increase the likelihood of young minds coming across valuable information such as this.
🧠🧠🧠🧠🧠🧠🧠🧠🧠
Dolores Umbridge ?
That was the best lecture I have ever seen.
The video is great and makes it clear how the pressure works for air and liquids and such, but how would the joined trumpet shapes react to sound. If one half is similar to the old ear trumpets that increased the sound, is this saying that the increase in sound is similar to the speed pf water, and that the increase in sound is matched by a decrease in some other quality of sound.
Right on smarty pants, well explained and demos. Nice job!
This seems rather unintuitive, but you explained it very clearly. Thank you.
Excellent demonstrations. best wishes for your channel growth
Muito boa a explicação. Obrigado! Para quem não entendeu o final, em 4:50 a velocidade é calculada dividindo o "volume de ar por segundo" (12 l/s = 12000 cm3/s) pela "área da seção" (3 cm2) = 4000 cm/s = 40m/s
This phenomenon is one of the most mind- fucking results in all physics to me. The fact that blowing air with high pressure through a tube with a restriction causes the air to decrease in pressure at the restricted part is so counterintuitive. My brain just will not understand how increasing the space in which a fluid can flow causes the pressure of the fluid to increase and vice versa.
Finally a good explanation of Bernoulli's principle
The first demonstration (with the 2 balls) perfectly explains porpoising in Formula 1.
I have an interview question (for the post of nuclear scientist ) on this principle.
Qsn)can we use the pressure sensors at throat and diverging sections gives the same result .
Qsn)do this arrangement give same result as traditional arrangement (pressure sensors at converging and throat section).
thanks a lot, the physics is wonderful
I had to subscribe! Amazing video!
In realms of air where wings take flight,
A dance of forces, pure and bright.
Bernoulli whispered secrets old,
In currents swift, a tale unfolds.
Above, below, a magic play,
In skies where dreams find their own way.
A symphony of pressure and speed,
A waltz unseen, the laws decreed.
As air flows, it weaves a song,
A melody where forces throng.
Upon the wings of birds in flight,
Bernoulli's dance, a graceful height.
At curves and bends, in fluid grace,
The air, a partner in this chase.
Velocity and pressure dance,
In every move, a sweet romance.
From wings that lift to planes that soar,
A principle forevermore.
In tubes, in winds, in rivers wide,
Bernoulli's truth, an endless guide.
A theorem sung in skies so blue,
In clouds and dreams, forever true.
A whispered secret, nature's rhyme,
Bernoulli's principle, through space and time.
I love this!! ❤
ChatGPT?
Me, using ChatGPT 😄@@bindum7178
This felt like something straight out of Ace Combat.
❤
Yes, very obviously ChatGPT
This just blew my mind.
I think that this didn't explain the nature of the effect - the *behavior* of the particles (or strings) in flow relative to "stationary" ones.
A part two to the video, with particle animation, where you visualize the pressure exerted by particles which do not flow is very much needed in my opinion.
Very simplified demonstration of the basic principle of Bernoulli .I wish some body could have explained me in my school level in such a lucid language.
Venturi, excellent illustration.
You made my echocardiogram studies easier, thank you
What ? Hiwnplz
I mean how plz
Do you know the auto stop mechanism of gas pump to prevent spill over is based on Bernoulli's principle?
This is counterintuitive. How did I live these whole years without knowing? How many more are out there that I think I know but I don't? Holy Castana!
Fascinating video. However, I am not sure that the ball hanging in the water coming from a tap is really demonstrating the Bernoulli principle.
Firstly, the water is not being constrained to flow through a narrower channel - it is free to flow over the surface of the ball and so the cross section of the flow is probably not reduced.
Secondly, if you look at the flow of water coming off the bottom of the ball, it is deflected to the right after it has flowed over the surface of the ball. Changing the direction of the water flow to the right causes a reactive force on the ball towards the left, and this is probably what makes the ball appear to cling to the water - the ball comes to a rest where this leftward force is balanced by the rightward force of the downward water flow pushing on the ball.
I agree that the ball in the running water was not explained right or enough. But I think they meant that the change in the pressure of AIR around the running water causes the movement of the ball, not the pressure of the water. For some years now I have wanted to know why the spoon is pulled by the running water. And to me it looks like the curved shape plays the major role. I doesn't happen when you rinse a knife.
@@sylwiagotzman5422 Have a look at the video: Why are so many pilots wrong about Bernoulli’s Principle? by Fly with Magnar (th-cam.com/video/uyRx25MSWng/w-d-xo.html). IMO he explains quite well what you're describing, it is the same as for an airfoil. Spoiler: it is also Bernoulli's Principle, and has indeed to do with acceleration of the fluid at the convex part of the spoon
It's the Coanda effect, not Bernoulli's Principle, that pulls the spheres or spoons together in a liquid or gas flow. The experiment would not be able to be replicated with cubes instead of spheres.
That's one of the educating channels you subscribe to.. once a fan of science always a fan of science
So... the two balls were "sucked" towards each other because the two balls created a small channel for air or water to pass, thus creating lower pressure compared surrounding space (atmospheric pressure). This lower pressure in this smaller channel creates a vaccum, pulling the balls together.
Kind of. The higher pressure on the outsides push the balls together. There's no "pulling".
Fantastic use of the word _thus._ 😄
A pressure difference in stead of a vacuum.
Yeah i think it's also due the the specific shape of the sphere.
it's not the vacuum that pulls the balls. You've said it: it's the atmospheric pressure that pushes them.
__
for a 3 cm radius sphere we get about 1 N:
P=f/A; f=PA = 101 Pa * 4Pir^2 =101*0.0113=~1 N
Beautiful video. What a cozy nice accent. I loved it.
The correct term is to say `Bernoulli's' Integral', since it is just an integral of the Euler's equations of motion for a particular case of steady, inviscid and potential flow. The term `principle' is related to something very fundamental, like The Principle of Least Action etc.
I honestly hope nobody is watching this video for Education purposes. Because my soul died in the first 2 minutes
That name is popularly known by people.
You can get the same equation by cancelling viscous terms and triple integrating Navier-Stokes' momentum equation. If I can do that, then it should be called the Navier-Stokes-Bernoulli equation, and it's not that
A name is just that, a name, so people can easily recognize the equation
I would have loved to have seen this video as my younger self, it explains perfectly why airplane wings work
The pressure reduction is due to the expanding exit and not the narrow part of the system. The width of the entry may not be important but the exit, the wide exit creates a sudden increased volume hence the reduced pressure. I would like to see the same experiment be done without the expanding exit and see if there will be any differences
now this got my interest,
you explained it better sir 👌
The exit or diffuser has been measured (not estimated) countless times to have increase in pressure, the negative peak of pr3ssure coefficient is at most right before it, if your brainstorm was close to right the entire racing industry would be incorrect.
That happens at supersonic speeds
Very nicely explained basics.
Very nice work
Flow is displacing molecules between. Thus, flow displaced by volume pushes molecules.
Excellent..!
The flow of a liquid or gas following along the outside of a curved surface is the COANDA EFFECT!
I really LOVE this video
Back in the 80s we had Bernoulli Boxes
These were large (for the time) memory disks using the Bernoulli principle
I know you have a large queue of ideas, but could you please put a video talking about this video along with one explaining the Bernoulli Box?
that's hilarous
Merci Bernouille !
I worked on an evaporator the use the Venturi Effect powered by low pressure steam jets.
An Air brush functions by a certain velocity of air passing laterally down a tube of said diameter - at a mid point down the tube is a T- piece with a pipe leading to a semi liquid media /paint source -
A pressure is formed at the pipe perpendicular to the main pipe due to currents being generated by the air flowing through the lateral pipe.
The flow of current in turn causes a vacuum at the pipe perpendicular to it. - With a carburettor this is called down-draft.
Its basically a pressure created by many things travelling at speed - Aircraft, Cars, Speed Boats - - If you have wondered why if you leave your tail gate open you get chocked by exhaust fumes being sucked back into the car.
If P1 and P2 are different then how come fluid volume (say gas) remain the same at those two points ?
I love this woman's voice.
All Jet engines work on this principle on convergent and divergent ducts.
Pressure and Flow = volume per minute - Just like voltage and current = watts. The amount of output remains the same even though you are changing the ratio of pressure to flow.
Is it same for liquid?
or what changers?
Great video
You made my day with this
Glad you enjoyed it
What about the speed of the flow in the narrow section ?
Hello. This is partially miss informative !
The Bernoulli theorem is challenging, but it kind of makes sense in a CLOSED system. You could think of it in lines of that you have roller coaster carts attached with springs. As they start rolling downhill the speed increases and the cart in front is pulling the spring to the next cart and vice versa. When they are slowing down uphill ... the springs compress (higher pressure) when the speed decreases.
Now when you start blowing stuff in to the surrounding atmosphere it gets messy. The two spears getting drawn together, it is because of the coanda effect. The pointed jet sucks the surrounding air with it and creates a low pressure. NOT to do with Bernoullis principle. I know; It is complicated :). The ball hanging under the water flow, counter intuitive or not has to do with the coanda effect, i.e. water being sticky and curving around the ball, hens creating an opposite force to the curving acceleration.
Oh well. Always have doubt, if your intuition says that something is not necessary so ;) .
You are right.
Finally someone pointed it out! There are so many misinterpretation regarding Bernoulli's Principle. It has rather strict assumptions for the fluid and the system (closed system, inviscid, incompressible, irrotational, no external force other than gravity etc.) and is not what people think it is.
Another wide spread rumor is that lifting force of a plane can be explained by Bernoulli's Principle. It is so wrong that NASA specifically wrote an article titled "Incorrect Lift Theory" for it:
www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/airplane/wrong1.html
Most videos claiming to be showing Bernoulli's Principle are NOT doing it under correct assumptions. Sigh.
Thank you for your effort, but you're assuming the surface is (or that it even could) pulling the air towards itself which is blatantly false, Coanda is a mere observation that air tends to follow the surfaces which is false as soon as flow separates, and it works on water because 1- surface tension and 2- water is much denser than air.
All aerodynamics forces are pressure driven, like Newton on fluids, which is the correct way of visualising it.
@@davidaugustofc2574, the Coanda effect also occurs with air (not just water) flowing over a curved surface, and is the reason for the spheres being pulled together with air flowing in between and for the sphere being pulled into the water flow. The same result does not occur if you use cubes instead of spheres. Those experiments do not exemplify Bernoulli's Principle, which applies to a single fluid flow. It is the pressure difference that causes the velocity difference, not the other way around.
@@mattcarter1797 My problem with the Coanda effect is that it is a gross oversimplification of the entire thing. You need to understand a little bit from several topics to understand what it really means, and those topics are more helpful than the conclusion.
Air is mostly neutrally charged, as gas molecules usually are, so the external electron layers will repel each other, a gas would expand to Infinity if it had a chance and enough time. However, due to the local, gravitational effects from the Earth, the air is squeezed together, and the balance of those is the atmospheric (sometimes known as static) pressure.
Gravity makes it so that pressure is very even for the same height all across the globe (temperature changes aside), so when a moving body is going through air and changing the pressure around itself, there will be a restoring force acting on the fluid to bring the new pressure value back to the original one. That is pressure will flow from high to low until there's negligible difference between the areas.
When the air gets close the surface it's pushed away by the first layer, that's attached to the surface due to friction, and when the surface curves away from the direction of flow it forms low pressure pockets that will exert less force on the surface and nearby molecules that the air surrounding it, thus guiding the air towards the surface. (Greatly helps if you have a way of visualising it)
And that's very simplified in it's own rights, since vorticity is a humongous topic on it's own, that I haven't even touched. I cannot understand how we're helping people by telling them about the Coanda effect and not the reasons behind it, you can't really learn anything from it. Okay, it was a great discovery for their time, but we're now at a stage where computers can generate airfoils from a set of requirements, we need to point out that air tends to follow surfaces and move on to deeper topics and not keep hanging on to it as explanation for anything.
This is great!
This video is WRONG.
The statements about Bernoulli's Principle are correct, but the demonstrations are very poor.
The balls, spoon and funnel age a result of the Coanda effect.
.
The tube inserted into the wall of the neck is protruding into the flow (seen at time 2:57) This causes the air to curve around the end and sides of the tube. This curved flow is the cause of the lowered pressure. This will work with no pipe around it; just the air blowing across the vertical tube.
..
To correctly measure the static pressure inside your narrow neck, the end of hat tube MUST be flush with the inside surface.
..
At time 4:51 we see that the two pressure sensing tubes appear to be more like flush, but it is difficult to see clearly. For that to truly sense the static pressures, there must be NOTHING protruding into and disturbing the flow.
MIND BLOWN
Thank you so much; Really awesome! But why did you say that the volume decreases rewriting the formula of kinetic energy which is valid only if the volume is the same? Maybe I didn't get it well; can you explain, please? Thank you.
Yes that was a mistake. The fluid is considered incompressible so no change in volume (capital V) occurs. Only changes in its velocity and pressure. Also the volume disappear entirely from the equation, as shown.
Now it's clear. Thank you very much for your generous activities.
V2 is smaller than v1
The case of the liquid faucet and the ball may conflated with Coanda effect
I have always had difficulty providing an intuitive explanation for this phenomenon, but if we try to think of pressure as potential energy rather than force per unit of surface area, perhaps the concept becomes a bit more intuitive. Or, imagine having a blown-up balloon. The balloon has a certain internal pressure. When the balloon is opened, the air inside the balloon starts to move faster. The internal pressure of the balloon then decreases because the potential energy of the air inside the balloon is converted into kinetic energy.
Good analogy
You have to embrace pressure to reach your full potential.
Intelligent video how to make a Bernoulli bong.
As the speed of the air increases the ball redirecting the air has a boundary layer that causes the air to follow the curved surface . Air has weight . The air is acting under the laws of Centrifugal force as it is held to the ball by the low pressure boundary layer and causes what we call lift. Air accelerated across a curved surface "wing" creates lift by the weight of the centrifugal force directly relative to the speed . The faster the wing through that air the faster the air has to move to follow the wings surface which creates centrifugal force by kinetic energy. A wing flying just above VSO can not be over stressed . But above VNO can be overstressed easily . More airspeed across the wing more centrifugal force the air creates on the boundary layer. Such an experiment if I remember correctly was conducted on an F16 wing with a porous top wing surface where more vacuum was introduced I would suppose to slow the stall break. Boundary layers lifts NOTHING . It is the area between the wings surface and the fluid movement of air which can not do anything above VSO but adhere to the upper wing surface curvature creating a vacuum across the wing . The blunt nose of the wing along with angle of incidence only accelerares that air. The Whittman wing for the Tail wind has a thin wing with a sharp leading edge thus high take off , stall and flying speed. Ultralights use a very rounded leading edge to compress the air flow across the wing this a low stall speed .
Your test tube is after the smallest opening, so the pressure is decreasing. The pressure increases to the maximum AT the smallest opening. It increases, then decreases suddenly like a divergent rocket nozzle trading pressure for flow/thrust. Like a transformer trading voltage and current with the power being the same except for the small loss of the transformer.
THANK YOU SO MUCH!
Good channel needs more subs.
I just wish someone would taught me like this when i was young.. when TH-cam was not that much a big hit and we had to pay exorbitant prices for just 1GB of internet data in India at that point of time we had to imagine all we could.. but now seeing this animated video with real life examples is what giving me an epiphany that what i imagined at that point of time was correct…
I'm waiting. Not forever. That's the message.
This demonstration also covers the Coande and Magnus effects, maybe even the Casimir effect.
3:00 and there you have a CARBURATOR!
A Venturi. Used in some priming pumps.
When moving at considerable speed, this principle becomes tactile; breathing with wind-force against ones face 'should' make inhalation easier by intuition; however it is not the case, the faster the wind approaching ones face the harder it is to inhale, in-fact the lungs volume is wrenched from ones throat instead, and only an eddy-of air-pressure will allow ones respiration at-speed.
It's not true that faster air flow implies lower air pressure. Bernoulli's Principle only says that a faster section of flow within the same fluid flow must have lower pressure than a slower section within that same flow. If you stick your head out of a fast moving car and face forward, it should be easy to inhale.
"the lungs volume is wrenched from ones throat"
Maybe the wind was pressing against your chest too and that forced the air out of your mouth.
Good explanation
Offshore, we use the kinetic energy of a fast flowing water as pump, we call this process an ejector...
1:02 would the same thing happen if it's a laminar flow?
how u find that if there is a section of 3 square cm, whit a flux of 12 L/s; the velocity is 40 m/s
Cross section area = 3 sq cm. Volume flow rate = 12 litres/sec = 12000 cubic cm/sec. Dividing the volume flow rate by the cross-section area of the tube will give us the average flow velocity: therefore fluid velocity = (12000/3) cm/sec = 4000 cm/sec = 40 m/sec.
Well done!
This is how a carburetor works.
When you blow on two balls the pressure can also increase so much that it can become very messy 😊
Is it legal to teach this in Florida?
Is that the Venturi effect?
Randomly stumbled to this video and thankfully I clicked it. Now I understand how the soap get used when my father use the his pressure washer with bottle of soap on the water gun.
Bernoulli's principal as applied to aerodynamic lift, doesn't fit. When air pressure sensors are applied above the wings of a C-172, according to data, the aircraft could not achieve lift below 400mph.
🔥🔥🔥Amazing work 🔥🔥👍👍
This video is WRONG.
The statements about Bernoulli's Principle are correct, but the demonstrations are very poor.
The balls, spoon and funnel age a result of the Coanda effect.
.
The tube inserted into the wall of the neck is protruding into the flow (seen at time 2:57) This causes the air to curve around the end and sides of the tube. This curved flow is the cause of the lowered pressure. This will work with no pipe around it; just the air blowing across the vertical tube.
..
To correctly measure the static pressure inside your narrow neck, the end of hat tube MUST be flush with the inside surface.
..
At time 4:51 we see that the two pressure sensing tubes appear to be more like flush, but it is difficult to see clearly. For that to truly sense the static pressures, there must be NOTHING protruding into and disturbing the flow.
If you control the sizes of both ends of the funnels carefully you can get supersonic air flow from non supersonic air flow.
very nice presentation.
Constant enthalpy for open systems!
I need lots more like this|
You can buy replacement shower heads, which promise to increase the force of the water spray at (I presume) the cost of some decrease in the total volume of water leaving the shower head in unit time.
It does seem to work, but the effect is (imo) rather too feeble to bother about.
And thats how maby not best, but most simple, and most reliable air pomp is made. Industrial usage of it is huge
I learned nothing, but had a great time doing it.😁🤟
i wish i had seen this in my college days
that's logical!
Its intuitive that the air pressure would be lower on the far side.
Science is amazing ❤️❤️❤️
Does this mean if you suck air into that funnel the ball will fly out?