How fast moving water “defies” gravity
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- čas přidán 28. 06. 2024
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A powerful jet of water pointing downwards can actually hold up an object against gravity! But how? I think I've worked it out. Let me know what you think of the explanation. Video also features: Hair dryer levitation and hand blender levitation. Are they related? Well it's all fluid dynamics, that's for sure!
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"Somewhere above absolute zero" is exactly how I want my weather forecasts from now on.
Greater than zero people liked this comment.
If 5g becomes popular it just might be your dream come true
SorroWaifu Are you claiming that 5G data systems will drop the global temperature to somewhere near absolute zero? Because if so that seems like it'd be a great way to combat global warming!
Absolute zero is -273.15 C , so u don't want it to be
I also think I'm greater than the zero people, whoever they might be.
"I like shouting Bernoulli" ~Steve Mould 2019
That killed me 😄😄
@@blakekelly4547 so many scenarios went into my mind...
Mr. Mould with a boom box over his head and a green overshirt out in the rain.
Victorian Mr. Mould "Bernoulli Bernoulli, were art though Bernoulli"
A beat up Mr. Mould in boxing gloves "BERNOULLIIIIIII"
Was literally going to write BERNOULLI!!!!!!!!!!!!!!! but you did it so much better ;-)
Omg I couldn't stop thinking he needs to say Bernoulli until it finally happened 🤣🤣
Me toooo, was shouting in my head!
Sounds like the real explanation is that Bethesda wrote the physics engine of our universe.
Lmao
Nope, it was actually Dice with their FrostBite engine.
giants: *exists*
dragonborns: "WHEEEEEEEEEEEEEEEEEEE"
Never should have come here
😂 Gold
i love this mans 'stays up all night thinking about the mysteries of the universe' energy
Hahaha! Or "the things we take for granted" cuz were too bored/cookie cut to explore outside the box.
Steve Mould, 4am, running naked though the streets of London.
“BERNOOUUUUULLIIIII”
Why is this what you picture? What lead you to complete this thought from what he said? I didn't get the same implication you did. Who hurt you? Why do you want to hurt Steve? Do you need help? Is there someone we should call? I have so many more questions, but am unsure if I want any answers.
Why would he be naked?
@@CitizenSnips69 It isn't something that can be explained, instead it needs to be experienced.
@@CitizenSnips69 Probably a humorous rendition of Archimedes and the "Eureka!" story
And yeah, sure! I like Daniel Bernoulli
Do the blender with ethanol or similar lower surface tension liquid to establish the role of surface tension!!! Also explosions!!! :-) ;-)
there's no way I waste my vodka on such silliness
This is a great/terrible idea!
I mean sure, or you could just use soap? ¯\_(ツ)_/¯.
@@newperspective5918 think of the bubbles!
oh yes. Maybe as a colab with Colin Furze - ?
"...which was something I didn't know how to do until I learnt."
From now on any questions about my abilities shall be answered with this.
And now I learnt from you 👍
Someone shouted "Bernoulli Effect!" at a Shellac gig I was at. Was that you, Steve?
7:51 I think we all enjoy a fresh cup of blended water in the mornings, really gets me going anyway!
I'm more of a stirred water kinda guy.I think blending the water takes away to much of the flavor if you ask me.
@@themeditatingdog6402 as long as I strain it, I'm good either way
I'll take my water shaken, not stirred. Thanks.
prefer mine thrown down stairs and slurped out of the carpet.
I only absorb my morning water through a hepa filter wrapped round a sponge which has iced over night in the freezer. The solid sponge ice is melted in the microwave to the point of steam then condensed and left to drip over a laminated passage from a magnetic North facing bible. When the sun light is strong enough to trip a solar alarm next to my water glass, its time to drink the condensate. Seems to work no too bad tbh
the source engine is really starting to show its age, the physics are just plain broken now
Rena Lockwood I heard they’re going to try to patch it though, I say they should just roll out 2.0 on the current engine
The engine is so broken that the temp gauge is just sky rocketing too. I say we just switch to the 4D engine, its still in beta but its pretty nifty.
ah, that explains where my dad went
@@forbandyson8921
Maybe he found them. That would explain the temperature going up...
@@GeeTransit i think i saw him stuck to a pole downdown
6:09 "it's just navier-stokes" me explain every fluid phenomenon from now on
of which it is contended that there is no analytical solution
I love your approach to yhese subjects. I find most youtube channels take a basic topic ,that all of already know by simply living on earth, and "explain" them as if it's this brand new discovery and that they have all the answers.
And altho science can be fun and interesting, most people aren't that thick.
Your intuitive way of teaching / sharing what you've learnt is exactly the type of content i wish to be invloved with. Thank you for the refreshing videos.
I like the "Humble Tau" book in the background at 6:37.
Yep, love it
Did you notice that it changed back to humble pi at 7:03?
omg I didn't notice it said "tau"
@@EmeraldKing213 whaaaaat it suddenly changed
@@srpenguinbr That's because the book is actually called 'Humble Pi' by Matt Parker, and it is an inside joke that Steve prefers Tau over Pi.
In my estimation, my immediate intuitive answer was vacuum pressure. I recon that if you did the blender thing, even though it has something to the effect of a kilogram of lift, it wouldn't pull the beaker off the table until you got it RIGHT to the bottom of the glass. What I'm seeing in all of the cases is a motive force flowing a fluid through an evacuated medium faster than external particles are capable of flowing in to fill the space. This creates a low pressure zone and pulls the restrictive member toward it. So, when the membrane (lid) is placed against the nozzle, you are restricted to a single sheet of outward flow, with no air or water allowed to flow back in, lowering the pressure of that layer, This in turn creates a feedback loop: low pressure pulls the membrane in, causing restriction, and restriction lowers the pressure which pulls in the membrane. So, to reproduce this, you just need a system that can produce micro-vacuum pockets that interface with the restrictive membrane to produce the lift. this is seen with the water example. The vortex motion of the blades draws bubbles of air in and the sheering force of the blades is breaking the tension on those bubbles, causing them to collapse and reduce the pressure in the fluid.
Awesome! I'm doing my fluid dynamics class is august and this video got me pretty pumped (no pun intended). It will be fun to come back and see if it makes more sense after the class but my, general knowledge based, knee jerk reaction was thinking about some kind of fluid 'wetting effect' where these particles would be sliding alone the surface causing friction and pulling the surface back against gravity. i would think that's why the first two examples work and are pretty 'weak' or unstable. more wetting effect and surface tension with water so a slightly more stable hold with the first example and a more temperamental hold with the air flow as small bumps could cause the sheet to slide of centre (reverse air hokey). however the last example had me at a loss as i wouldn't think surface tension even at the speed of the blender would be enough to support a kilogram of force to become unstable, so after reading your comment looks like that's what ill be looking into :) so thanks. I'm sure all these factors are applied to create the result. very cool video :) keep up the good work. (again this is probably not the answer just my thoughts and I'm happy to learn).
Immediate thought too. Specifically for the blender one. Don’t think it applies to the first two effects.
I need an aspirin!!🧠🤕
"And you know this intuitively from playing with an air-filled syringe..."
Ahh yes, a classic plaything. Literally hours of amusement for me.
But... like... it literally was for me tho, its pretty fun actually
@@khasanbekmalzagov6240 yeah seeing that actually gave me a hit of nostalgia.. I'd completely forgotten I used to do that
that was one of my best toys.
Blessings of the 3rd world right there!
Didn't have one in your kitchen, maybe a Turkey baster same concept
That rolling shutter effect at 7:30
STEVE!!! Your explanation is partially correct.
This phenomenon is indeed a result of a difference in pressure but this is not a result of a change in density! Especially in the case of water, which is nearly incompressible.
The microscopic reason for all these observations is that since the particles have a higher velocity parallel* to the containing surface, they "bounce" less against this surface for a certain distance traveled. It is exactly this microscopic bouncing that is the cause of pressure itself.
I also strongly doubt that surface tension plays a big role.
The example of the Styrofoam sheets and the hairdryer, the animation and the Bernoulli principle should explain that there is lower pressure at the edges of the Styrofoam sheet and higher at the center. I get lost when thinking about the total pressure. Your explanation sounds more reasonable.
I'm 95% sure this is the full explanation. Incidentally, this is the intuitive explanation of Bernoulli's principle we are taught at the University I attended. It's all to do with energy density.
I was one of the people yelling "Bernoulli."
I am pretty sure that your explaination is just another way to describe why the density of a fluid changes as well as it's pressure, when moving. You have to understand that liquids and gases are essentially (well solids for that matter too) the same, they only differ in density but they all have the same properties (density, viskosity, ...).
That said, i do think that the minimal change in density does in fact influence the pressure change, if you would compress a liquide, you would have the same result, even thought the density change is almost non existend, it will greatly influence the pressure.
Quite like with the density change of fuels. They have a lower density at higher temperature, even thought this being a very small amount, ships have to account for this because they could carry up to 1 ton of fuel less than in lower temperature climate.
Mandernach Luca except that that’s not true. Particularly for solids, the bonds formed between particles in different matter states are significantly different. Ice, for example, is less dense than chilled water but has significantly stronger intermolecular bonds holding it together. Different bond patterns can form different properties, as in graphite/coal/diamonds. It’s not just about being squished or stretched.
Everything else you said, though, is pretty on point.
@@Panic_Pickle
Molecules always have the same bonding energy, what changes is the internal energy of the molecule or the heat energy. There is a point where the heat energy of a molecule is higher than the bonding energy, that's when a solid turns into a liquide, increase the heat energy above the sum of
bonding energy and pressure energy (for example at 1 athmosphere of pressure, or about 1 bar) and the liquide will turn into a gas. The only difference between gases, liquides and solides is their bonding energy, wich is constant for individual molecules. We classified them as such because they are as they are at room temperature and 1 atm, the normal conditions of our enviroment.
Properties of meterials can be applied almost universal, granted hardness of water might sound weird but at the right circumstances, even that property can be applied to water.
Properties like density, viskosity, thermal expansion rate, stiffness, hardness (measured in resistance to penetration) can be applied to liquids, gases and solids.
As an extrem example, a capsule that does not quite enter in the right angle into the athmosphere, can bounce off of it.
The same applies to a submarine that, tryes to dive from a salt lean water layer into a salt rich water layer, it bounces of when entering in a flat angle.
Water is non-compressible, though. I was thinking about pressure head and velocity head as factors causing reduced pressure at some points, but then you mentioned particle density and it really made me think. I'm not sure how to reconcile the hypothesis that lower pressure is created by decreased particle density in water as I imagine there would be no change in particle density in water.
Edit: I cleaned up my grammar because this comment got enough likes that Steve Mould could feasibly see it and I was embarrassed.
Good observation, and also the water effect is in that cupped shape creating a water seal, and even needs the water to be forced up and over the edge, which means another downward force component.
@@Jim73 I also noticed the water being deflected upwards and found it fascinating that whatever force was holding the plate to the hose was not overcome by the force from the deflection.
Perhaps the effect has something to do with Volumetric flow?
Water is compressible. Why is everyone spreading this myth?
@@monster2slayer Yeah it is, but at those scales compression is unnoticeable
6:53 You see the water rushing upwards and into the sides of the glass. I'm sure friction alone would have a pretty strong upward force, pulling the cup upwards with the water. Obviously this isn't the only force but you mentioned intuition, that's what I saw for a split second without thinking about it.
I was thinking something like that as well, glad you noticed. Its like lifting a glass by putting your fingers inside and expanding them so friction makes so it doesn't fall
Exactly what i was thinking, but it's a little more complicated than that i'm sure. Do you see the little air bubbles, i think that's cavitation. Little air bubbles that are greated from the spinning blades. When they go away, maybe it greates a lower pressure that pulls the glass upwards 🤷♂️🤷♂️
@@night__walker i think you are more correct than them in this case. It just doesn't make sense to me that that amount of water at that velocity can create the equivalent of 1 kg of upwards friction, i imagine maybe 100g of friction at the most, which obviously helps. I'm open to be prooven wrong about how much force is produced by friction so take that as an opinion.
But i think the more substantial explanation is that, in fluids an increase in velocity is accompanied (in some cases) by a decrease in pressure, especially in reduced areas, like the space between the styrofoam boards or the space between the glass and the hand-held blenders end. In both cases there is a reduced area with a fast moving fluid, so the pressure right above both objects is really really low. Now for a change, let's say we drop one single styrofoam board and one single glass cup from 1 meter /1 yard of height, in both cases we have pressure from the air below it, pressure from the air above it, which cancel each other out and the weight of the object, so the object falls depending on the weight only. In the cases of the video, we have pressure from the air below (1 atmosphere), we have the weight and we have the pressure above and inside (in both cases less than 1 atm). This difference in pressure results in a force upwards, that apparently (and maybe with the help of friction) can overcome the weight of the object. Hope this helps, cheers!
@@yonidellarocha9714 yeah very good explanation. Understanding how different pressures work is fascinating. I will always remember the first time i realized how a vacuum cleaner really works. It's not the vacuum that pulls stuff in, it's the higher pressure forcing the air into the vacuum cleaner, because there's a lower pressure and they want to equalize.
@@night__walker with the hand blender it's all much simpler. The rotating blades are pulling the water up from the bottom and ejecting it out of the little ports on the sides. That's the low pressure area inside the housing against the glass, like a vacuum stuck to your hand. This is creating most of the lifting force in this case, still pressure differential causing the force but much much simpler to understand in this case.
5:22 you forgot to draw an important force, the one that makes peoples intuition faulty: the force of the hairdryers jet pushing down in the center (before the air is diverted sideways). The pressure difference has to not only overcome gravity, but also that force.
The blender example reminds me of how drones and toy-helis are sucked up onto ceiling if you get too close. And I would argue it is caused (at least in part) by the same effect.
Though it also reminds me of the ground-effect, where drones/toy-helis need less torque to hover than fly, thanks to sitting on the pillow of air achieved by their propellers pushing air downwards. Makes me wonder, did you really try it with the mixers propeller spinning both directions? Or might it perchance not have angled blades? Nvm, saw a shot of the blades, they are mostly flat (even pulling water up from "floor" a bit, like how a drone pulls air down from ceiling), explains that.
7:00 So, you have yet to explain why this effect you are describing/showing only appears when it counteracts gravity (when the jet is pointed downwards), and why, if in the initial example you had held the plastic thing in place like you did when pointing downwards, it still flies off as opposed to sticking to the hose.
finished video. Why were the water example made to have a rim going up past hose, while the air example didn't? Technically you can argue the mixer example had a rim too. Is it needed for this to work with water? Or was it just cause it was easier to make the parts that way, and it potentially actually makes the effect worse/weaker?
You are right about positive pressure from dryer and that is reason i would still stick with Bernoulli.
For other part, about direction, no, reason plastic thing flew off in air isn't because stream is upward, but because he let it flew away before stream between surfaces is established. If he hold it for the first moment while opening water, effect would be same as in opposite direction, but it would be pointless from video recording perspective because we wouldn't be able to see if it's hold by water stream or by gravity.
@@mrblc882 On the contrary, he wouldn't show it launch the plastic thing upwards, if it wasn't to juxtapose how this effect only works when counteracting gravity.
Which is why I have no idea how the effect actually works (his explanation fails to explain that), as naively I would assume it works both directions (like you say), but he decided to prove that it doesn't
As for the hairdryer point I made, it was mostly just nitpicking that he forgot to draw a force (and that it is the one that is the most important to explain), I still think his explanation about higher-air-velocity -> lower-air-pressure seems correct for the hair drier example.
Also, wow what a necro, I had forgotten this entirely xD
@@feha92 no, he just wanted to show that stream is powerful enough to lunch that plastic part in air, but effect is caused by forcing stream between surfaces, which doesn't happen if you let plastic fly away before stream flow between surfaces is created.
Regarding explanation itself, I still think it's Bernoulli effect. As I wrote in separate comment, you can recreate effect with shower hose (when you remove shower head from hose and pull nut back, not possible with all types of hoses) and effect is proportional with speed of water between surfaces (smaller gap or bigger flow). Area difference on shower hose is too small for his explanation.
Also, with his explanation, force will be greater on outer parts od styrofoam plate and middle part would bulge downwards (because of positive pressure from dryer and higher density). On the other side, Bernoulli effect depends on speed, so pressure drop (and force per area) would be highest around hole and edges could be twisted downwards (less than center with his explanation because only reason is gravity).
@@mrblc882 I say atmospheric pressure is responsible for both effects. In the case of the hair-dryer, the air pressure at the edges is much lower than the pressure at the nozzle but as the air rushes away from the tile, it creates an area of lowered pressure above and below the perimeter of the two tiles. This causes the top tile to be pushed down while the bottom one is pushed up creating lift.
In the case of the hose, the water creates a seal that prevents air from entering the chamber. (That's why he has to wait until the the container is filled before he attempts to defy gravity.) The water pressure is pushing the container _away_ with a force of maybe one or two p.s.i. while the atmosphere provides a force of more than fourteen p.s.i. _in the opposite direction._
If Steve had had the integrity to turn the container upside down, the the fourteen p.s.i. would have forced air into the container and it would have flown upward.
SmarterEveryDay needs to do a follow up to this, given how much Destin is into fluid dynamics. The hand blender thing was cool.
This channel is defying 'content gravity'.
Which is where the weight of having to keep producing new content makes the quality go down.
This channel's quality is keeps going up! Thank you Steve (and team!?)
Hey, thank you! It's mostly just me. But when you see good quality animation, that's Dom Burgess from the Every Think channel.
@@SteveMould There have been a lot of shots where the framing and timing has looked really difficult and you seem to have pulled it off with such ease, I was sure you must have had a helper. Even more impressed now.
Three years later - this evaluation still checks out.
this happens a lot with me, when i make my smoothies, trying to keeping it from sucking itself to the bottom of the glass.
Tilt the blender cup (shape part) so it does not create a vortex vaccum
I think it's to do with the velocity-pressure relation, where a fluid flows faster creates lower pressure. Similar to how putting a table tennis ball on a blower magically sticks it to the center of the air flow. You got fast flowing fluid creating pressure low enough that the atmospheric pressure underneath is enough to force whatever object above
I'm just glad I wasn't the first thinking of this :D
@@Hienix Steve was the first to think of this when he brought up Bernoulli's Principle in the video lol
@@Phillip29473 this video Washington not the first time I had contact with fluids mechanics, in chemical engineering this is analyzed, not this case specifically but the underneath concept behind it. I've said I wasn't the first because someone prior to me replied it.
me: *watches first 3 second* ok, i get it.
1 second later
me: WHAT?
The immersion blender is just a pump jet, creating a very imperfect vacuum seal under the housing.
Also very inefficient, you're starving the pump as it tries to evacuate is housing.
If you tilt it, breaking the seal, now it gets going and pumps all your fud through itself, a very efficient way of making a smooth blend as it both blends _and_ cycles all the food through it. You just have to hold it at just the right angle while in contact with the base.
Don't get it wrong, you'll coat walls with food.
👍👍👍
Good discovery, Steve! The devs might patch the glitch next update so might as well enjoy it while it lasts.
Maybe I'm to late, but I may found a solution for the handblender-effect. If you look at the behaviour of a handblender you will notice, that the blades are designed to suck liquid from underneath and (because of centrifugal force) push it out trough the slots on the outer diameter. Therefore the handblender is acting like a pump. In open space the fluid is circulating but if you get close to the bottom the gap is to tight to provide enough liquid to get trough. because of that pressure decreases and the "pump" sucks to the bottom. I hope this makes sence...
I literally just sent a message to Veritasium last week about this effect asking him to make a video on it!! You beat him to it, but I'm so glad someone actually did a video on this!
3:00 That's actually a drone shot of Derek in his pool with some shade balls.
@@massimookissed1023 😂😂
SportsRGreat wdym?
@@tinzalix8624 Apparently you're a sellout if you get millions of people excited about and engaged in science and teach them about it for free, if you find a way to make money doing it. Such a shame, he used to not be making any money...
@SportsRGreat r/iamverysmart
I love your video topics. Really interesting phenomena found in normal life, explained clearly.
I love how when you started explaining I got so focused on it that I completely forgot about the crazy blender magic trick . I love your videos keep them coming .
This is what happens on the top surface of an air-foil (like on a wing), you are creating lift through pressure differential. The velocity of the air/water coming from your hair dryer/hose creates a region of lower pressure on the top surface of your styrene/plastic cup than the ambient pressure found below the styrene/plastic cup so you get lift.
The *cause* of the pressure differential is the interesting part here; it's not that the velocity inherently creates a zone of lower pressure, because when the jet hits the surface it's blocked, which creates a small high pressure zone. What actually happens here is that the fluid jet being blocked causes the fluid to be shot sideways in all directions at higher velocity, but because it's diverging, the fluid "front" (imagining a discrete pulse) is spread over a larger cross sectional area. Crucially, I believe the spreading disk of water has "supercritical" velocity. This means that its momentum maintains the outward flow in all directions, preventing the space from "filling up" as we would intuitively expect. At the same time, this diverging flow means that any given "chunk" of fluid is being spread over a larger area, and so its radial velocity must decrease if the flow rate is to remain constant. Its momentum resists this, which causes a pressure drop; the low pressure pulls the fluid away from the jet and holds the surfaces together.
With a blender, Water is creating an "air tight seal" which is not letting the flask fall down.
The blender is held by hand and the rotating blades are thrusting the water towards top hence pushing the blender down which keeps the blade below water most/all the time.
For the flask to fall, AIR from top of the flask needs to reach to the bottom of the flask otherwise it will form a vacuum. And to fill in the vacuum, the flask is being pushed up by the air surrounding it because of air tight seal by water... water is being pushed up by blades and blades are being pushed up by hand.
Water is acting like a giant suction cup.
Yeep seems legit. That and bernoulli pretty seem to explain these but I'll have to have a long sit down think to see why we might be wrong
I think a good way to test that would be put a small hole at the bottom of the flask and experiment to see if the water keeps the blender grounded after the hole is uncovered
@@patricioansaldi8021 You're right, a hole will change the whole story! ;)
Aakash Kalaria since no water needs to leave the beaker for this to work it is safe to assume that no net force is generated on the beaker as a result of upward moving water. The amount of water being forced upward is the same as the amount of water moving downward. Also if it was true that the reason the blender demonstration works is because of the water being pushed upward then a force should be felt by the user regardless of its position relative to the bottom of the container. That is not the case however as a force is only felt near the bottom of the container.
@@elilesch522 the force is felt by the user, since you have to hold up the flask/water and not just the weight of the blender
I like the shot of you pouring it out of the beaker. It's been too long.
It was just for you!
Thank you so much, Steve, for bringing such beautiful videos on this platform for us. You really inspire me alot!
Relatable moments with Steve Mould 1:17
I like shouting Bernoulli as well. Sounds like a Monty Python skit?
Bertolli!! No wait. Bertolli’s principle and bernoulli’s pasta.... gadamn itai’s...
I PANICKED!
@@lohphat That would be Burma.
@@steamsuhonen9529 The trouble with LED TV's is that they're not thick enough to put a penguin on. Click thumbs up to crush a troll.
I'm still lost about "Bernoulli". You all did something tho!
If you Google "What does shouting Bernoulli mean?" It links this video.
The hand blender act like a centrifugal pump, where the "propeller" is the rotor, and it create a drop of pressure. There is something called NSPH, that's is explained by Bernoulli's Principle, and it consider the static pressure of a fluid, the dinamic pressure of the same fluid and de vapour pressure. If the NSPH is grater than the factors before called, the pump cavitates, pitting the rotor. Is very important in fluid dynamic this concept, because it leads to low efficencies and more costs of repairing the pump.
Great Videos Steve, i enjoy very much seeing them.
Greetings from Argentina!
Edit: Some of the effects can be explained by the inicial part of the Transport Pehnomena, written by Bird, Stewart and Ligthfoot, and is a incredible book from micro scale to macro scale, including heat transfer. Also, the book Hydraulic and Hydraulics Machines by Stevenazzi (I got the spanish version Hidráulica y Máquinas Hidráulicas).
Yes, I think it's acting like a centrifugal pump too.
One of the best science and engineering channels out there. I learn a lot of cool new stuff from you because you explain everything as simple as it can be. The nerdy jokes that come with your videos are as welcome as they can be.
The hose pops off unexpectedly creating an epic comedic moment!
6:50 Humble Tau in the corner😂.
Benjamin Lehman OH MY GODS
How did I not notice that LOL!
By... who? "Mint (???)" instead of Matt Parker
I really thought "Isn't that Bernoulli effect" LOL
Good Video! Love your "home experiments". I would not have predicted the results you show. That's cool.
The hand mixer is a centrifugal pump, drawing in water in the center and expelling it through the holes in the rim. All centrifugal pumps develop a low pressure area at the inlet of the impeller which both causes the fluid at the inlet to flow toward the impeller and creates a thrust on the pump shaft, due to pressure imbalance on the impeller. In real-life pumps, that thrust has to be dealt with using thrust bearings, but in larger pumps a dual inlet impeller is often employed to balance the pressures and forces on the pump shaft. Pump impellers also use seal rings to isolate the suction area from the discharge area, further increasing the pressure imbalance.
I like your videos and have learned a lot about fluid dynamics.
Unfortunately, though, it IS Bernoulli. Or specifically - Bernoulli GRIP
“With careful design the pressure in the high velocity airstream can be lower than atmospheric pressure. This can cause a net force on the object in the direction normal to the side with lower local pressure.”
I saw some info on robots using this to climb walls and windows. Check the IEEE:
spectrum.ieee.org/automaton/robotics/industrial-robots/robot-uses-supersonic-jets-of-air-to-stick-to-almost-anything
spectrum.ieee.org/automaton/robotics/industrial-robots/geckoinspired-window-washing-robot-is-powered-entirely-by-water
This is exactly what I was thinking throughout the entire video, good find!
I don't think he was saying it isn't Bernoulli. He is saying that simply saying that it is Bernoulli doesn't necessarily help one understand why this is occurring.
It isn't bernoullli because Bernoulli only applies to a closed system of fluid and this system isn't closed.
Additionally, just saying "Bernoulli" doesn't actually help anyone who hasn't taken college physics.
@@fshihab The fluid is not in an enclosed environment and is free to flow through the air.
Hence Bernoulli is inapplicable here.
Bernoulli only applies to Newtonian fluids flowing through pipes and the pressures considered are relative to other pressures in the pipe and not to the outside world.
This feels connected to the Coanda effect, only because it's in an almost closed space it creates suction. Air flows down (vertically) until the lower plate gets close enough. Then the air flow reflects of the lower (and upper) plate being pushed outward, the air flow becoming horizontal. So now the air flow sticks to the upper plate and the lower plate sticks to the air flow because of the Coanda effect IMO
Teo Filimon
The Coanda effect ?
That's odd... and that's also why airplanes have reaction engines - cool to think about but how is jet surface modulation related to this ?
Try this:
Go to the bathroom.
Unscrew your shower head (on the shower hose). And be careful not to lose that rubber ring.
Make a fast jet of water with the hose and put your finger next to it.
When you touch it at first, it will pull on your finger and the water that comes out after the interaction with your finger will be chaotically dispersed.
However, after you obscure the jet hard enough, the jet outgoing water will suddenly turn into a clear thin umbrella and your finger will suddenly be pushed away from the jet.
After you retract back your finger and the jet is no longer fully obscured, the outgoing jet will suddenly turn from that clear umbrella shape to the chaotic spray you saw first and it will start pulling on your finger again.
Btw, it has a hysteresis effect.
I believe that this is somehow related as is an effect that accounts for the transition between pushing and pulling and it also accounts for the increased stability of the system in either state.
The only problem is that I have no idea about how this effect is named or if it is even addressed somewhere else.
NO your on the wrong line of thought
nickacelvn
who and how ?
I think the hair dryer experiment works thanks to the Bernoulli principle (less pressure between the polystyrene surfaces than the outside), while I think the blender and garden hose experiment work differently:
I believe that the water pushes on the inner walls of the container, creating a sort of "internal grip", as if we imagined taking a glass not from the outside but from the inside by spreading the fingers
I agrée on the first point but can’t decide on the second point
@@joeyuzwa891 very late to this video, but water's surface tension is actually quite strong, so as it is forced up the edges of the glass, maybe surface tension is providing enough friction to pull the glass up as well? Also, this only works when the blender is placed flat against the bottom, indicating that it has something to do with pressure. My guess is that when the blades of the blender 'pull' water up very fast, a low pressure zone beneath the blades and above the bottom of the glass is established. This seems like it would be the larger contributor.
I say atmospheric pressure is responsible for both effects. In the case of the hair-dryer, the air pressure at the edges is much lower than the pressure at the nozzle but as the air rushes away from the tile, it creates an area of lowered pressure above and below the perimeter of the two tiles. This causes the top tile to be pushed down while the bottom one is pushed up creating lift.
In the case of the hose, the water creates a seal that prevents air from entering the chamber. (That's why he has to wait until the the container is filled before he attempts to defy gravity.) The water pressure is pushing the container _away_ with a force of maybe one or two p.s.i. while the atmosphere provides a force of more than fourteen p.s.i. _in the opposite direction._
If Steve had had the integrity to turn the container upside down, the the fourteen p.s.i. would have forced air into the container and it would have flown upward.
IMHO.
@@michaeladams8858 I think the blender effect is kind of suction cup effect. As you say, there is low pressure area caused by the water trying to escape from the blades, and at the same time water also works as insulator to prevent anything else to replace the low pressure water. I believe if you had a hollow shaft spinning the blades creating a channel into air the "vacuum" would fill with air stopping the suction cup effect and the glass would fall down.
However, I would think the other two things are caused by similar forces. That is because for all practical purposes, the only difference between those two was the raised sides on the lid. But I think those lids are irrelevant for this effect to work. Although that wouldn't readily explain why the water experiment only worked with the high pressure nozzle, but I think that could be explained by the vastly different scale of of the two experiment, one having much larger flat plates and thinner fluid, to mention just two of the differently scaled variables. I would've wanted more rigorous testing for the boundary conditions by changing the variables. That would have either confirmed or debunked my intuitive assessment.
I feel Bernoulli is both the hair dryer and the hose, but not the blender, based on the water jet creating a low pressure-region, thus pulling the plastic towards the nozzle. I think the hair dryer is doing the same thing, but using air. The blender likely is able to create a suction force that is greater than gravity pulling it down.
You are my favorite "goldilocks" science explainer. Always drilling down to just the right level of explanation. For the first third of the video I was thinking "hmm he's probably going to say it's Bernoulli... Even though that feels more like a label than an explanation". Then in the middle third I was thinking "yeah sure that all makes sense. ...he still hasn't said 'Bernouli' though, isn't this pressure-velocity-density stuff just a specific incarnation of Bernoulli?". And then in the final third, "ahhhh there we go"
Let me just tell you that you did a better job than my engineering professors.
You can do the same with a minecart and a fishing rod, Steve.
is this a minecraft reference?
or is it ...jojo’s?
:o
Screw all that... just use a sheep and a bucket. The bucket for your water elevator and the sheep will act as the memetic boost capacitor.
You do get the inevitable byproduct of a water sheep however. So take this into account.
@@dmitritelvanni4068 I think water sheep are kinda cute, even with all the sharp spines.
Nice job making the animation. Love that sort of stuff.
"Something I didnt know how to do... until I learned"
What a mind boggling concept
When you confine the outward velocity to a layer you get a uniform layer of molecules as opposed to the random motion outside of the confinement. You're basically "stealing" the inner pressure. I.e. if you take a 1mm volume of ordinary thermodynamic particles the average *velocity" is zero. When you think of it in polar coordinates ... your dual plane set up goes from a net 0 velocity to a net outward velocity ( no negative r ) when you turn on the hair dryer. And as a result the pressure outside has the up/down components and the inside does not.
BTW, if you like using JavaScript to do animations, you might take a look at WebGl or three.js. Three.js is easy. WebGl is comprehensive but hard.
Very interesting Steve. I blend food and sauces every so often and even in larger containers I can feel the "suction" effect. It works with thick liquids like soups which obviously have differing surface tension properties than water.
Wow. This is one of the few videos I've seen of his that I genuinely didn't know how it worked. Awesome
You are fantastic. I have learnt many things from your videos that I didn't actually learn at the school
5:55. “I like shouting bernoulli as well”. Upvote
9:50 - the Humble Tau makes a cameo
I think Bernoulli does have an intuitive explanation. Say a molecule is in a box, it would be bouncing around, hitting all surfaces in all directions equally. But if it starts heading in one direction in a flow, say without energy input, then now its velocity is in that direction, and it wont bounce off the sides of the channel constraining that velocity with as much force as if it were maintaining a static position (on average) within that channel. So with the polystyrene, the molecules between the sheets are zipping away from the hair dryer, lightly bouncing off the polystyrene, whilst the molecules on the underside of the bottom of the polystyrene are hitting it with more force, perpendicular on average = net upward force
It's like a mosh pit. The moshers would be hitting the concert goers around them with less force if they were also trying to run along a channel in the crowd and mosh at the same time.
The energy inside the polystyrene sheets will have a higher total pressure, due to the input from the fan in the hairdryer, but this will be (must be!) more than offset by the lower dynamic pressure due to the gap.
On your animations, the thing to consider is conservation of flow. If you drew the flow volume in two dimensions, it would be increasing with radial distance from the hair dryer. Flow going through an expansion slows down (Bernouilli!!).
IVE BEEN LOOKING FOR AN EXPLANATION FOR THIS FOR 2 YEARS! THANK YOU!
1:51 that my friends is the face of pure terror
6:59 *ALRIGHT STEVE! YOU'VE HAD YOUR FUN! NOW, WHAT ON EARTH ARE DO DOING TO MATT'S BOOK?!?*
Functional Sausage
You break things down in a way I understand, thank you!
1:00 I discovered this on my own at work washing dishes with the caps for sauce bottles and the high pressure water jet we use to spray dishes. Never knew the specifics behind it but now I do!
I just want to say that I always refresh my subscribing feed and try to watch as early as I can because the youtube notification takes way longer to say that you have uploaded a video
So keep uploading man
Thank you
Advances in science do not come with Eureka's, they come with, "Huh, that's weird..."
The hose popping off at the end of the demonstration there is classic. These are some really thought provoking problems.
Love the rolling shutter effect going on with the blender at 7.40
Would the effect work in other directions? Would the hummus tray "stick" to the sprayer when you pointed it upwards (if you held it to the sprayer to start the effect)?
It wouldn't, water would fall down and break the seal needed for the effect.
That was my first thought too! Always turn it around to see if orientation matters.
It works in any direction, as long as there is enough air pressure -> doesnt work in space.
"I got sucked into naming a video…" was a good title, but really, the video could be called about 01:48 - "youtuber nearly decapitated by a Hairdryer and a polystyrene sheet"
For me the blender is like grabbing the water, so you are pulling the watter upwards with the force of your hand. The cup follows the water upwards because of the vacuum that exits between them, so basically is the atmospheric preasure is the force that lifts the cup
This happens with my hand in the hand dryer... thx so much for explaining!
I wonder if this could somehow be related to the ground effect phenomenon in fixed-wing aircraft flight
Maybe the Mixer is pushing the water up. And with the water the cup must go up, too because if it doesnt, there would be a leck of air/water and it would end in a lower pressure "sucking" it up again. Also maybe the water is addicted to the plate a little bit like it is if you put water in between of two plates even in a vakuum.
I think that the "hose-holding-onto-the-cup" phenomenon is where surface tension comes in to substitute the missing compressibility of air. Since the water hugs both the hose and the bottom of the cup, it's much easier for it to continue travelling along those surfaces than ripping them apart.
As for the polystyrene experiment, I think it really works by lowering the pressure in the area between the plates. You can try this by holding two sheets of paper a few centimetres apart and blowing between them. Thanks to the relatively high viscosity of air, the current you create grabs onto a substantial amount of air particles and as it travels past the area between the two sheets, it lowers the pressure between the sheets, pulling them together.
Steve - it's fantastic that what you show is repeatable by any kid right their in their home (or better, their back garden "yard!"). Really well done.
Great video! Regarding the blender, two things. First, if you analyze the angles of the surfaces the blades would act like a propeller push g fluid down, not up, so they don't help with the suction. Second, the suction effect is due to the vortexing. Also due to bernoulli's principle, a vortexing fluid has a lower static pressure, with the center being the point of lowest pressure.
...of course both the hand sprayer and the blended had created vortexes due to their rotating paddles moving the fluids in a spiral pattern.
I believe the centre would be the lowest point of pressure as the molecules are moving the slowest. The water molecules are the inside face of the beaker are moving the fastest. Higher velocity therefore, lower pressure.
Steve Mould's Greater Hose Pipe Houmous Lid Principle
I think the blender example is to do with cavitation, as blades can move through water so fast that they create a pocket of "vacuum" and this is responsible of the suction force between the base of the container and the blender cover in this case, but I might be wrong entirely.
The blender works to hold up the beaker foe a different reason. The blender is acting as a cenripetal pump. Normally it will draw in water from the center and throw it out to the sides. In this case the bottom of the beaker blocks the low pressure intake. Like being "sucked" up by a tiny puml that expells water through the side slits. The area of the intake matters for the strength of this effect too. If you were to fasten a flat plate with a hole in the middle to the bottom of the blender, it would pump water in through the hole, but also the largee area of the plate would allow more force for lifting.
"I like shouting Bernoulli as well..."
Bernoooly was a unicorn ever told but never seen until now! #ItDoesExist 1:50
Thank You Steve (priceless look) Mold.
If you like this effect, I highly recommend looking at venturi suction cups. I remember thinking it was really cool that you could power a suction cup by venting compressed air from a reservoir- it really challenged my intuition.
I love that the "most replayed" section is where the hose accidentally smacked Steve's hand when he tried to put it down!
Upside down air hockey table? Maybe localize the air to the puck with IR tracking on each wall of the table.
ny neck hurts
My hypothesis for this:
The water that is coming out from the cup is creating a negative pressure where the jet nozzle is, creating a vacuum - and the negative pressure exceeds the forces that would push it down. This would also be why the foam board sucks itself up to the hair dryer nozzle when it gets close. It sounds plausible, but the only detail that throws me off is that the force from a pressurized nozzle intuitively feels like it would be greater than the negative pressure keeping it up. Perhaps by disrupting the flow so abruptly(by slamming it in to a wall, essentially) and having it happen in such a confined space the forces aren't as great as imagined, or the negative pressure could be stronger than imagined too. Any thoughts on the idea?
You had me until the end, the total force to redirect the stream from downwards to up over the lip with be the same regardless of how abruptly or how much area it is spread out against. I think you are right about it creating a vacuum; I agree it seems so crazy that a vacuum's absence of force would be stronger than a jet that created the vacuum in the first place, but I can't think of any other explanation.
Added to amazing things to impress my kids on a rainy day. Nice one!
My guess on hand blender mystery.
Consider the following statements:
1. As said by Steve the blender sucks the water up. That as a result put a net force upwards on the water.
2. Air from the atmosphere cannot reach the bottom of the glass because water is denser.
3. Due to the above fact and the fact that water cannot be expanded easily, the glass and water will fall together only.
From statement 1 we see that the due to the running blades water is pulled upwards and the glass will not fall leaving the water around the blender (unless there is a hole in the bottom or air reaches the bottom of the glass) as a result the water and glass do not fall.
You can imagine this as the water and blender tied together and the water and glass tied together.
I do not think it has anything to do with surface tension because it is negligible compared to the gravitational force and turning the blender on only increases the surface energy (surface area of the water increases) which in result increases the energy of the system and hence making it unstable. So surface has nothing to do with this.
You deserve more subscribers.
"i was shouting bernoulli..." - hans moleman
Now we need to see Action Lab do this in a vacuum chamber to see if it will NOT work. I guess he'd have to do the water jet experiment.
Gr8 discovery man! For the last one,(and yes I don't understand fluid dynamics much but) if it somehow(an important somehow) effectively utilises the rotational energy to produce a upward, fastening force, I can't stop thinking about applying this phenomena in orbital docking technology.
I mean maybe it couldn't hold up in big cargo transfers but maybe inside stations? I am just anxious to see this phenomena in microgravity.
C'mon aero guys, let's figure this out!
7:40 - well, you know what you have to do now: fill your power hose with washing up liquid.
Watching these videos, I always feel proud of our school's curriculum here in Turkey. Sure most of the students don't actually learn much, but I always paid a ton of attention. Whenever I see a video like this that explains a natural weird phenomenon, I can actually explain the reasons by myself only using my high school knowledge. And everytime that happens, I just feel great.
Here is what I think is happening with the hand blender experiment :
I think it is a two parts phenomenon.
1. As the blades spin, the centrifugal force they generate moves the water radially and a low pressure area is formed at the center. The difference between the low pressure in center part of the bottom of the beaker and the atmospheric pressure above the water creates a suction between the beaker and the hand blender. This is evidcenced by the constant production of cavitation bubbles seen at the bottom of the beaker as the gases dissolved in the water gets out of solution in the low pressure area.
2. The displaced water has only on place to go when it is ejected from the center by the blades, wich is upward (since water is not compressible). The water go up the walls of the beaker until its energy as dissipated (or until it is weaker than gravity). For the hand blender to get out of the beaker, the water above it has to get back down to replace the volume occupied by the lower part of the blender. However, since the water coming up is blocking the narrow sides of the blender's lower part, the water can't go back down, lowering the pressure even more in the bottom of the beaker.
I think that the hand blender at the end of the video is the perfect tool for making good hummus, which brings us full circle to the beginning of the video.
The blender is designed to create cavitation bubbles, which is just another way of saying it creates little vacuum pockets in the liquid.
I believe you, but I don't think that's the main effect at play. I think it could create the necessary seal even if the blades minimized cavitation, but I'd be curious to see
The awesome part is that gravity is the cause of ambient pressure, and thus gravity creates the buoyant force that opposes gravity (just like a wing!).
Yes, but no gravity would make flying much easier.
@@bonemasterj Hmm...without gravity, wings wouldn't work, but you wouldn't really need wings would you? Regardless, gravity isn't going anywhere!
@@radguitar1 Exactly.
Understanding this effect took me so long to figure out as a young kid, but I loved it when I did so because it made mechanical devices like throttles, vacuums, air paint brush feeders, and so many other things make more sense.
That's Benouli, I think, certainly in the case of carburettors. Steve is trying to figure out what the underlying physics is, which is altogether more tricky
Coanda effect came to mind along with surface tension boundry layers.