As some have pointed out there is definitely more going on here than just air pressure. In fact you cannot talk about any fluid flow with only talking about pressure. You have to always talk about fluid velocity and pressure together. We do know there is the centrifugal effect of water being thrown out the sides and also down the middle. But the reason there is ever any flow at all is due to pressure differences. The ball is being dragged down by the water but it is also moving fast and so the atmosphere pushes it down as well. There is also rarified air and eater vapor that forms under the ball pushing it up (maybe). This is definitely a phenomenon that I have never seen before in any literature so if anyone has any resources are open to hear more about this.
But isn't pressure in a fluid inversely proportional to its velocity? Shouldn't there be more pressure in the centre, where the fluid is at its slowest? A.k.a.: imho, the ball doesn't sink because there is less pressure in the centre rather than on the sides, although that could explain that anyway through a reduction in Archimede's force due to the lowered pressure
Also, I don't think atmospheric pressure has anything to do with it, because once it is underwater it can't affect it, but I haven't seen the full video yet. Might cancel the comment. Edit: I was wrong, atmospheric pressure plays a role, but I still don't think it works like you said. When it's completely sunk there is no way for the air to push it down, since it doesn't make any contact with it.
I thought the ball would go down for the same reason your helium balloon goes in front of the car when you drive. eg the water is heavier than the ball and will move toward the wall faster than the ball who get pushed center. With less force pushing the ball upward the ball sink. As for the ball going up I agree with other comments about water vapor since your other videos shows that water boils at that pressure. For the same centropic reason the vapor is also pushed toward the center under the ball.
The type of 'spinner' you used has a serious effect on this experiment. The agitator at the bottom, is in effect, a sort of centrifugal pump. Water is constantly being flung outward at the bottom, then forced up the walls of the container and flowing back in toward the center (all with considerable tangential flow as well). (this is why this type of 'mixer' is so often used, it circulates the fluid both tangentially around the container, but also radially outward, upward, and back down in the center) This downflow in the exact center, IMHO, is what drags the ball below the surface. After all, when the ball is completely submerged, the air isn't acting on the ball at all. As others have pointed out, as the water spins around it also has centrifugal forces acting on it, so the surface of the water is always perpendicular to the combined centrifugal/ gravitational forces acting on it. It would be very enlightening to use a different mechanism to 'spin' the water. For example, remove the agitator and spin the entire beaker. With all the water spinning at the same RPM, you would not set up the same internal flow pattern. The water at the bottom would not be 'pushed' outward to the walls of the beaker any more than any other water, so there should not be any 'vertical' circulation. Edit: Without this, I predict the water will form a parabola, but the ball will not be 'sucked/pushed' under the surface (much like you saw it under the high vacuum condition).
"spin the entire beaker... I predict the water will form a vortex in the middle" - it won't create a vortex funnel. It will form a concave parabolic surface. Like liquid mirror telescopes.
@@sangnguyentan1911 I believe he's referring to the shape the water surface would form if you spin the entire beaker as I suggested. Near the very center, with centrifugal force very low and gravity, the shape of the surface would be nearly a flat plane. Only as the radius increases does the centrifugal force become significant and then the surface curves upward. This is exactly how a mirror for a reflector telescope is started. The final shape has to be ground precisely, but the basic concave shape is formed by 'spinning' the glass while still molten.
@@TheActionLab i think it was floating a bit because the air was getting pulled from the water so that force kept it up is what i think instead you should drop the Ball after a vacuum
Consider repeating this with very cold water and see if the lower vapor pressure makes a difference. Or measure the temperature after doing this experiment with warm water. The evaporation/boiling may have already chilled the water by the end of the experiment.
As has already been pointed out - Water boils under vacuum. The cooler the water is, the lower the atmospheric pressure needs to be to reach the boiling point. With a low enough pressure, tap water will boil at room temperature. Yes, that's a Fact!. If you place the ball on still water and then pull a vacuum, the water will boil all around the ball like a pan of water on the stove, only the water will NOT be hot to the touch. As the air is evacuated from the chamber water will reach a point at which it boils. Right after this, the vacuum gauge will stabilize and stop dropping until all the water is gone, then it will drop to whatever level your pump is capable of pulling on your vacuum chamber. In your experiment, the "air pocket" that formed under the ball while rotating the water is the water's gaseous state trying to reach the surface. This action creates a lifting force. The bubble formes in the middle of the vortex since this is the water's lowest pressure point. Going a little off subject. Something else interesting about water is it has a "triple point". That is the temperature and pressure at which the three phases (gas, liquid, and solid) can coexist in thermodynamic equilibrium. Under the correct circumstances, water can turn directly from ice (a solid) to gas without first becoming a liquid.
Waauw Action Lab. You invented a simpel physics-setup that causes discussion among physicists! I envy you! I have my doubts about your explanation, but I cannot come up with a better one (yet).
2:00 I'm just gonna add that centrifugal force is pulling the water outward causing a toroidal shaped circulating system. A vertical cross-section thru the centerline would show the flow directions to be clockwise on the left and counter-clockwise on the right side. That is why the water level rises when the spin starts. Oh, a little addition here. Forget air pressure. Gravity is pulling the ball down. Air pressure is a function of gravity. Low vacuum causing vaporization of water beneath the ball with cavitation. Water vapor evaporated off the water at low pressure is accumulating under the ball and creating a small pressure to move the ball up. All great videos.
Each of these videos is worthy of a 10th grade science assignment. I sourced and got inspiration for one of my assignments in the action lab video about heating up water by blending/stirring it. I conducted my own experiments and ended up getting full marks. Thanks for the effort and information put into these videos.
Note that a mag stir plate is a centrifugal pump. Drip in some plastic powder, or some dye! The flow is down the axis, radially across the bottom, then up the glass walls. (But, what if the water is boiling at room temperature? Instead try ice-cold, well-degassed water.)
Man you constantly come up with original and interesting experiments. Happy to say this is not some pop science channel. Your really teaching lots of people obscure and interesting science.
In the normal pressure part, is it really the pressure from the air that sinks the ball, or the fact that the moving water is moving faster below the ball than above ? Perhaps the high-pressure experiment will tell. In the low pressure experiment, the air vortex below is likely to be vacuum, and the ball seems to be just floating on the walls of the vortex. These are my hypotheses.
Agree. The velocity of the water below is faster than that above the ball, producing a downward force due to the pressure difference(in addition to the original pressure difference).
Great experiment! Overall air pressure has no direct effect on the ball - it pushes it down (via water) as much as it pushes it up. But the lower pressure allows building of steam- bubbles. They gather in the middle where the pressure is low and they build eventually a vapor column that wants to go up and pushes up the ball. It would be interesting to see the experiment with slightly warmer or colder water...
That little experiment that you did with the straws also illustrates how carburetors work. As intake air flows at extremely high velocities into the barrel and through the venturi, it has extremely low pressure that sucks fuel out of the float bowl and into the intake to join the air rushing into the engine. Carburetors aren't used on cars anymore; they're exclusively fuel-injected now. But carburetors are still extremely common on GA aircraft, particularly those powered by Continental or Lycoming motors.
Got my subscription box yesterday !! Bit late but hey, I am sure there were good reasons. It had more than I thought it would. Quality hoses, brass fittings, thread tape for fittings, 2 wrenches, a vac gauge, patch,sticker, pin, instruction book and experiment book ,box with marshmallows -balloons - shaving cream. I like it all. Hope the next one is a bit more timely but I am sure you all were making a great effort. Maybe you got more orders than expected or ?? Thanks..
I’d die from alcohol poisoning. He really thinks low of his viewers with 100 rehashes in a video. “Lower pressure, ok guys you get it now? Lower pressurezzzz”
Hey I have to commend you on your awesome videos, I've learned a lot! One thing I must offer up in this one is, in the first case, it actually sinks for two reasons. First, centrifugal force and buoyancy act outward instead of downward as with gravity only. Second, the mixer is a turbine. It's pumping, sucking the water down from the centre (where the ping-pong ball is) and throwing it outward and up the beaker walls. A common statement of Bernoulli's principle, the well established concept that a fast moving fluid is simply at lower pressure than anywhere downstream, is false. The common diagram of two large pipes connected by a smaller straight section of pipe, with a manometer connected midway in each section, showing reduced pressure at different points, may indeed work as depicted, but it is an incorrect way to measure pressure in a moving stream. The reason for the above is because of the effect of the boundary created by the measuring tube. The same effect is created by the trailing edge of a venturi, tending toward the suction which causes gas or droplet entrainment. The correct way to measure pressure would be to have a pressure transducer surface flush and nearly indistinguishable from the interior surface of the passage it is measuring. This way there is no disturbance to the flow, and so the pressure measurement would prove independent of flow. The diagram depicted above, applied to a venturi, with or without the correction last stated, would work as depicted because the measuring location is at a *_change_* of flow shape/velocity.
i disagree with you conclusion: the ball goes down because of the water flow. when you reduce the pressure you boil the water and the tendency is the densest fluid go outward. this, then, creates a zone with water vapour instead of water, having less thrust downward. think of the stirrer as a pump that sends water from the bottom back to the top and you will understand. when the water vaporizes the pump starts to 'cavitate' and the total flow is reduced. this only happened because the vortex widened at the bottom. with a taller vessel or wider ball or a fluid that wouldnt evaporate at this low pressure (some polimer maybe?) you wouldnt see this effect. a test you can make to prove this is to fill the vessel to the brim with water and seal it. there is no air pressure and the ball will go down because of the 'convectional' water flow. you could even make a hole in the top of the lid and vacuum it and as far as there is no significant amount of water evaporated to start forming a cone the ball will stay down.
Even I completely agree with you. For some reason I couldn't agree with the explanation even after showing a practical. I too think it's just the water flow and not the air pressure causing the ball raise
Agreed. Maybe he could try it without the ball? The shape of the dip did absolutely nothing until the water started to boil. Doesn't that need an explanation? Or try it with a piece of polystyrene with plenty of holes drilled through, to let the steam escape.
and, watching again i noticed another point: the 'air' beneath the ball is not air but water vapour that accumulated down there because the ball diverts the downward water flow from getting in the center of the spinner. bellow and above the ball where are gases (the 'inner cone') the pressure will be the same (a pressure low enough to evaporate water) . in the wet part of the ball are where the forces happens: buoyance and drag find equilibrium with that 'amount' of ball. the cone does not form by air pressure. it forms by inertia of the fluid climbing up the walls by the "velocity/energy" imparted unto it by the impeller, centrifuge forces and all that. by making the vessel closed at the top and filled to the brim you prove that: the water returns to the top and fills back the conical cavity without having the chance to climb. to see the flow you could add some purpurin or other solid particles.
Rafael Ramos da Costa boiling is not an other process, The ball is locked. Maybe there is something more than pressure going on, but simply boiling will not do from my perspective.
"When water moves it creates a low pressure. This is because when water moves it creates a low pressure. We know this because when water moves it creates a low pressure. The pressure is low because the water is moving. When the water is not moving the pressure is not low. Blowing on this straw double proves everything i just said. Blowing on this clear straw triple proves it."
That was completely unexpected. Great episode! And thanks for not being run-of-the-mill. You come across like a kid playing with his toys rather than a science teacher with a curriculum to fill. It's a good example to set.
Right idea for the wrong reason: at lower pressure , the gas/water vapor bubbling out of the water will tend to collect under the ball. If that didn't happen, buoyancy would keep the ball where it was.
Hmmm...I don’t think you can attribute all of the air under the ball to dissolved air. It is not trapped under there like a plug. But I agree that this could be part of the mechanism. There is a lot going on here, there is water dragging the ball down due to no-slip condition at the surface of the ball. There is air/water vapor below the ball as you said probably pushing it up. There is air pressure above pushing the ball down that mostly goes away under vacuum. This is definitely interesting though
I have a hard time believing the air pressure could fully submerge the ball. The water would have to be less dense than the air in the ball. I think it's the water flow. The vacuum allows the water to rise higher on the outside. With more water on the outside and no water in the center, the toroidal flow forcing the ball down is greatly reduced. Not only is the flow reduced, the surface are of the water contact is greatly reduced.
I am really into space stuff and I really like this video because it shows things we already know about gravity but on an extremely small scale that I never would have guessed to be shown on such a small scale. Tyvm for the upload.
Great experiment! I think the explanation needs some work, though. If it's just the air pressure pushing the ball down, then how does the ball "know" about the air pressure when it is already underwater? The only way the air pressure should be able to "communicate" downward through the water is by changing the pressure at the surface, which would only increase the total pressure at every point below globally. For the ball to be pushed downward all the way, there would have to be a gradient in pressure decreasing from top to bottom, a reverse of the gradient that would be there from gravity alone (when there's no vortex). So I think Joël Séguin's hypothesis is more likely - that air resistance friction slows down the vortex at the top, and those layers of slowed-down spinning water slow down the lower layers a bit less, creating a gradient in speed from top to bottom enough to allow Bernoulli's principle to reverse the gradient in pressure that the water would have from gravity alone. The air pressure would then only provide the initial push down, with the friction-slowdown gradient pushing the rest of the way.
Well I showed in a previous video that the pressure propagated through the water so it doesn’t matter whether something is underwater or not it still feels the lower vacuum. For example if I had a balloon underwater in the vacuum chamber And I lowered the pressure of the balloon with still expand in fact that’s what I did in previous video. There is probably an affect due to the dissolved air or water vapor under the ball also
Yes, lowering the air pressure on top of the water should lower the pressure of the water below, but it should do so globally. Thus, a change in air pressure alone should not be enough to make the net force on the ball in this vortex experiment, when it is already underwater, change from upward to downward or vice-versa (i.e. the direction of the pressure gradient should stay the same). Pressure-wise, having air on top should only increase the pressure everywhere below just like having some extra water on top (with vacuum above). And my guess would be that dissolved air should have a negligible effect in this vortex experiment (i.e. not qualitatively change the experiment's result).
@@davidellsworth4203 I agree with you. It's not the air pressure that is pushing the ball downwards underwater. It's the pressure gradient. The same kind of pressure gradient that keeps the ball in the centre. Velocity of water will be higher near the bottom(as the strirer is at the bottom) than at the top surface of water. So pressure will be lower at the bottom. Same way velocity of water is high at the centre(so less pressure) and the ball tries to remain in the center.
@@TheActionLab It appeared right after you see bubbles of dissolved air into the water. These bubbles got trapped into the vortex motion under the ball, and caused the ball to raise up. I believe if this air or vapor has some way to escape from under the ball, the ball would sink again. It would be interesting if you find a way to remote control the stirring motor, and start the vortex after all air removed - including that dissolved in the water, or just stop and re-start it under vacuum to check my interpretation.
+ The Action Lab - I don't know if this is what causes the effect, but I spent a LOT of time boiling up multiple litres of agar in large conical flasks on heated magnetic stirrers. Thing is, you see the vortex at the top, BUT as it starts to come closer to the boil, bubbles start to appear. This actually helps us visualise what the liquid is doing. The liquid is thrown out from the centre of the flask, and hits the walls, and is deflected UP the outside of the flask. Once it reaches the top, it spills over into the middle, still spinning. Once it is here, it starts to sink, replacing the liquid thrown up from the bottom, so that we have a notable downward flow. Could it be THIS that causes the "suction" effect, when it is in fact the liquid flowing from top to bottom down the inside of the vortex that forces objects down?
2 questions, 1- what about the air exists in the ball 2- what about the gravity By the way that was cool to see desolved air is not boiling much in movement
It would seem to me, having observed your video as the pocket of air began to form under the ball (Thanks to the water essentially boiling thanks to your lowering the pressure -- and thusly the boiling temp-- ) that in practicality what was happening was you made a sort of pocket atmosphere, thanks to the flow of the water which actually prevented the air from simply rising out of the water like it would as if you just let it boil, which was actually exerting pressure that was fighting gravity as it built up under the ball. So it seems to me that the ball didn't rise because there was no air pressure to push it down, but instead the dissolved air from the water simply began to push it the opposite way towards the lower pressure of the vacuum! Nonetheless that is quite a fascinating phenomena you made!
Very interesting experiment! But as you point out in your comment there is definitely more going on. One place to start untangling it would be when performed under normal atmospheric pressure why the ball sinks completely below the surface? When you demonstrated the same thing w/o the ball the air column reached the very bottom, but with the ball, the air-column only reaches about half-way, while the ball reaches the bottom. I really doubt that the water above the ball is lighter, and also I'm sure they're both spinning with similar speeds (not sure which friction is higher water-water or water-plastic). Another question - when performed under vacuum, and the ball is half-way between the bottom and the top, there are empty-columns both below and above it. Are both these columns same level of vacuum (I mean there isn't some weird way small amount of air is trapped underneath the ball)?
Does the water in the straw rises up because blowing air above creates a low pressure, so the air in the straw goes out and rises the water up ? If yes, then why doesn't the air surrounding the straw replaces the blown air instead of the air inside the straw, just like the effect in the video of the table fan's back. I'd be glad if you'd answer. Not an entire video but just a reply would be more than enough. PS. I still praise the day when I'd found 5his channel 😍. Just a few days to go to finish binge-watching all the videos of AL
Instead of thinking about it like the air in the straw is leaving so it “sucks up” or pulls the water up, its more like the atmospheric pressure on top of the water in the beaker is pushing water down, causing water to go up the straw, like a mercury barometer. Normally pressure above the straw and above the beaker are the same, but when blowing air, the pressure above the straw is lower due to fluid air moving quickly (Bernoulli effect I think) so water is pushed up by the normal pressure air above the beaker
You're blowing the air above the straw away, so it creates a low pressure zone. And water rises to fill it up. Like a burning candle in a jar placed in a bowl of water
The ball is sealed. It's clearly a lot bigger when it starts to float but the density of the entire ball must be higher than than the "free" stuff around it. So it should sink even harder than it did before. Nice experiment!
Would you try to use a colored gas (should it not harm the mechanism of course) with the vacuum chamber so we can see the air leaving and entering the system? This particular experiment would be much better in my opinion
Something just hit me: you are Mr. Wizard 2.0 without the kid cohosts. I'm guessing you're too young to know who Mr. Wizard is, but after watching you for a long while, now, this has dawned on me. Trust me, as a late eighties/early nineties kid, this is a compliment.
TH-cam decided to recommend that video today, 2 years after publishing. The youtube (ro)bot finally understood that i am interested in such great discovery in fundamental physics.
Every answer raises a new question! Was that an air bubble you created under the ball, or did you inadvertently create a vacuum within a vacuum using the surface tension of the water combined with the force of the rotation to form a "chamber", with the ball acting as a draw? Would be interesting to see if the same thing happens with differently shaped objects like a disc, cube, or a cork; as well as without anything floating in the water.
This was the first thought that I had too. It would be interesting to see this experiment done with a glass or clear plastic sphere done in a low to zero G environment. The ball should actually want to move to the middle center of the sphere. There should be a layer of gas bubbles that form around the outside of the ball.
I imagine this situation involves gravity, centripetal force, surface tension, and maybe viscosity. Plus vapor pressure when the vacuum gets high. (Those alone are enough to make it hard to figure out, too!) Atmospheric pressure only matters in that it pushes closed the vapor bubble at the bottom. I don't think higher pressure will change anything relative to atmospheric. But congrats on finding some unexpected behavior!
action lab: your explanation isn't accurate. it's more to do with liquid flow than atmospheric pressure. also you are conveniently skipping the fact that at very low pressure the water is actually boiling at room temperature
I'm sure that someone probably mentioned this in the comments that I was too lazy to read. Water in a vacuum boils below room temperature. Anyway, there are my two cents... I should probably check the upload date aswell but I couldn't be bothered with that. Keep up the good work and have fun.
Great video. Just a reminder, all these are described by Venturi, bernoulli, coriolis.... I think would be a good idea to leave some references for people who want to go deeper. Again, great video, thanks for sharing
Very good experiment but you should find a way to start the stirer after all the air is vacumed, because I think ball rises due to the dissolved gases under it can't escape and creates a pressure upwards.
(This part of comment prior to vacuum chamber experiment) The downward suction can't be the result of the atmospheric pressure above the ball. If that were the case, the ball would sink some, but could go no deeper than just below the surface where the air is still touching it, but just barely. However, we know that is not the case because once the vortex starts, the ball goes well below the surface and sinks all the way to the bottom. My guess at this point is that the atmospheric pressure might help START pushing it down, but there will be a point where enough of the ball is submerged (call it critical mass, or an event horizon, or a point of no return) where enough of the ball is submerged that the water alone can act on it, and at that point the pressure of the moving water is lowered enough that the buoyancy of the ball is canceled out causing it to sink. The one part I'm not really sure of is whether there truly is an event horizon that must be reached before the ball will start to sink; it is entirely possible that the ball may start to sink immediately once the vortex is turned on. Of course, even if there IS a point of no return, where there is too much of the ball under water for it to remain on the surface within the vortex, I believe that point will ultimately be reached even in full vacuum. This is because of the funnel shape of the vortex. As long as the vortex still appears as a funnel-shaped whirlpool, gravity will ultimately pull the ball downward until it reaches the lowest center part of the vortex, and because the the conical funnel shape, once the bottom is reached all sides of the vortex will have contact with the ball, giving it enough contact to reach that point if no return causing the ball to sink. Even if the vortex does not take on the conical whirlpool shape in vacuum, the decreased pressure of the moving water may still be enough that the water pressure is below the threshold of the ball's buoyancy, which would still let it sink. The only way it DOESN'T sink is if the whirlpool doesn't form and there is indeed a certain amount of the ball that must be submerged before it will start to sink. Considering that the ball; sinks in three out of the four circumstances I've described, my prediction is a 3/4 chance that the ball sinks. Not to continue the video and see how accurate my hypothesis is. (Interjection with video paused as you seal the vacuum chamber) Okay, you activated the vortex and the ball sank all the way to the bottom before you even sealed the chamber, let alone before the vacuum was reached. All of my previous predictions are now worthless as they were contingent upon the vortex not being activated until the container was in full vacuum. Since the ball is no longer in contact with the air at this point, the removal of air from the vacuum chamber should not affect the ball in any way. Because the stirring mechanism at the bottom of the container will maintain a constant speed even when the chamber achieves full vacuum, that means the water will continue to circulate at the same speed as well, so the water pressure will still be decreased by that movement. Since the ball starting from the surface in vacuum (and the question of whether it would be able to submerge in vacuum in the first place) is no longer an issue, that really only leaves two possible results. Either the vortex retains its whirlpool shape because the water is still circulating in the same way and the ball stays at the bottom, or the whirlpool shape disappears in spite of the water's continued motion due to the lack of atmospheric pressure but the ball still stays at the bottom because the movement is still decreasing the water pressure. At this point I am FULLY confident in predicting the ball will remain at the bottom. Now back to the video. (This part of comment after the entire video) Okay, I can admit when I am wrong. Since this comment isn't actually posted yet, I could easily edit my predictions so it looks like I was right all along and nobody would be the wiser, but I'm not that kind of guy. I'm honest. And I'm curious. can you explain to me how the loss of atmospheric pressure affected the ball even when it was fully submerged, having no contact whatsoever with the air above the water's surface? I'm also curious why the whirlpool reaches the bottom when the ball is not within the container but fails to reach the bottom with the ball submerged while in atmosphere, but when it's in vacuum the vortex is suddenly able to reach the bottom again in spite of the balls presence. I am quite curious about these things, so I hope you can provide some answers. Oh, and I no longer need to ask you to find a way to repeat the experiment while finding a way to leave the vortex off until it's in vacuum; if the ball rose to the surface even when the air wasn't touching it, then it wouldn't be able to dip below the surface in the first place if the vortex didn't start until after it was in a full vacuum. I would be interested in seeing if the results remain consistent if the experiment were conducted on a larger scale (like a vacuum chamber the size of a room and a water container like a deep pool). Would the ping pong ball still stay on the surface at the center of the vortex? Would it float closer to the edge of a larger vortex? Would the larger vortex manage to pull it down where this small one couldn't? And what about different kinds of balls? With the larger vortex you could test several. Would a basketball float? How about an irregular shaped ball like a football? How about items even lighter than the ping pong ball? Would they stay low in the vortex or float higher up the side? How much mass would a ball have to have before its weight overcame its buoyancy within the vortex in vacuum? Would it require the same weight as it would take for a ball to sink in calm water? Less weight? More weight? So many questions! Of course I'm sure you'll never have access to a room-sized vacuum chamber, nor will you have access to a pool that would be the equivalent of that stirring container scaled up to be like ten feet across, so we'll likely never get to see those experiments. And I am also curious about the experiments you mentioned with increased air pressure, but that would pretty much necessitate a hyperbaric chamber. Although . . . The box of you vacuum chamber seals air tight. If you switched the hose around on your vacuum pump so t sucked air from the room and forced it through the hose into the chamber, then it would just be a matte of rigging clamps or belts on the outside of the box to keep it from bursting open (after all, it IS designed to withstand inequivalent air pressure, it's just that its current configuration is focused on the lesser pressure being INSIDE. Hmm . . . my creative building mind is percolating!). Anyways, awesome video! I love these experiments!
The ball is still being pushed down. The reason it goes up is becasue of that bubble beneath it trying to escape. The bubble is water vapour produced by the low pressure at the bottom (the reason the ball goes down) being less constrained by the pressure of the air. This is causing the water to vapourise in the centre. You can see this happening above the ball as well, the difference is that below the ball the vapour can not escape. As the bubble gets larger it actually does escape several times in the video by getting large enough to 'bubble' around the ball, when it does this the ball does drop slightly each time. This indicates that the ball is kept up by the bubble. If the ball had a small passage through its centre then the air would escape and the ball would stay at the bottom.
The ball moving down is not because of air pressure, it’s because the spinner acts as a pump. A pump has a low pressure side and a high pressure side. The low pressure side is the center and the high pressure side is the outermost part of the container. Water is being drawn into the center and pumped up along the outsides. The spinner makes a vacuum at the center of the container that is stronger than the buoyancy of the ball. When you place a vacuum on the entire enclosure, the relative vacuum of the spinner becomes weaker than the buoyancy of the ping pong ball. And no, the water isn’t boiling.
1:00 Yes, the Venturi effect is a thing, but the reason the pressure is low there is because the flow is diverging at that location. Venturi may be present, but it’s hard to be sure without actually knowing flow speed there, which you don’t.
Woah man this is it, what I was trying for a month, Now I understood the behavior of Blackholes, Your video gimme direction for my next experiment...........Now I'm gonna try it in my Next Javascript program with pure visualization..........
It doesn't look like a game of pressure. From what I see with this experiment is that the volume of water level remained same whether the ball was inside or outside. It seems that extra empty volume created below the ball kept the ball up. Since the volume below the ball may not be air due to vacuum chamber, it means there is simply not enough space for ball to sink in the water. Also because the air is sucked out, the density of water should increase which should also contribute for ball to remain up in the water. Can we do this experiment with just the water(without air)? This is definitely centrifugal force which created low density area in the center of water but when we removed the air from water, the density was increased again and ball moved up.
6:55 One unit of atmospheric pressure is completely arbitrary, so if lower pressure causes it not be pushed down as much, then yes higher pressure means it's pushed down more. Pretend we consider 0.5 atmospheres to be "normal", so you did your experiment on the range of 0.1 - 1 atmospheres, up to twice "normal". In the range of 0.5-1, you noticed "higher" pressure pushing it down more.
Assuming you can create a vortex in a vacuum the ball should sink down slightly at the very least by way of being at the center of a funnel whose walls are higher than its center. That might be worded a bit awkwardly, but put it this way: it’s going to be on top of the water, but the water level needs the center will be lower than the water level on the sides.
Good job, dude! You're on your way to understand how gravity really works. This is "centrifugal gravity" =) The water doesn't "suck the ball down". The ball actually falls into low pressure zone. Now think the same thing but to centripetal process... Then you'll understand how planets "attract" each other. And how parallel conductors "attract" each other. When actually they are just being pushed towards one another. All this is just an Energy conservation law explained with Bernouli's equasion.
The impeller at the bottom eventually creates cavitation and a little bit of boiling occurs as well. Even though inside the box is almost complete vacuum, the water still creates pressure as you go deeper, but the pressure is lower now and cavitation occurs easily. However, this phenomenon makes the ball sink not rise. But the water around the ball still creates pressure and pushes it up. When the pressure inside chamber is high I also think it causes the ball to go down to the low pressure created by swirl. Also the explanation using molecule motion and forces is equivalent to an explanation using fluid dynamics and pressure but the first one is at a more fundamental level. For example the flow of a liquid creates low pressure around it because the molecules near the edge are hit by the moving ones and the volume around is depleted of molecules so new molecules come to occupy the place and so on.
Water boils in a vacuum so it wouldn’t work, and whirlpools generally have a down current, air doesn’t have that much pressure on the ball compared to the water.
When you remove the atmosphere above the vortex the vortex would have to strengthen because of the pressure gradient force, therefore the ball gets pulled upwards. That’s the reason why tornadoes are so intense, because the internal pressure falls within the mesocyclone (above) are so intense that it pulls upward and stretches the vortex vertically and strengthens it.
Hydro dynamics with a hollow ping pong ball. The stirer is pushing the water to the sides and goes up the cylinder, and what goes up must come down, the waters surface tension is grabbing the weightlessness of the hollow ping pong ball, is pulled down by the water returning to the bottom of the cylinder which make it act the way it did
Water is essentially incompressible at these pressures, little if any volume change. There is a pressure gradient in the air above the rotating water column.
The straw experiment ( like a draft in chimney) is like there is a static rest connection with a vertical column of air and a continuing column of water directly beneath the column of air .So that when a section of that column of air moves away from its rest position the connected column of water wishes to stay with that moving air it was associated with .The whirlpool experiment water is pretty much incompressable The ball then is being aided by a force that is pushing the water back so it can descend As in the vacuum this force stops it must be air There must be a very thin layer of air between the ball and the inside wall of the whirlpool holding back the resistance of the water pressure to let the Atmosphere push the ball down
Partly true, the starting point of everything is when a positive charged spinner is in a negative charged jar of water, the water is chasing the spinner around which is creating a vacuum for the air to full into.
This is the kind of video you have to watch multiple times just to meditate on how basic everyday physics works. I didn't quite understand a lot of things until now. It's interesting, the different interactions between liquid (water) and air/vacuum, with gravity being a key ingredient. When you lowered the pressure in the chamber, you sucked out all the air, but not the water. Gravity was too strong to do that quickly anyway. However, you induced evaporation/boiling in the water due to the low chamber pressure AND the even lower pressure from the spinning in the center of the beaker. That's really interesting and it seems like some kind of mechanical computer could utilize these facts to make a sort of water-transistor or something.
As some have pointed out there is definitely more going on here than just air pressure. In fact you cannot talk about any fluid flow with only talking about pressure. You have to always talk about fluid velocity and pressure together. We do know there is the centrifugal effect of water being thrown out the sides and also down the middle. But the reason there is ever any flow at all is due to pressure differences. The ball is being dragged down by the water but it is also moving fast and so the atmosphere pushes it down as well. There is also rarified air and eater vapor that forms under the ball pushing it up (maybe). This is definitely a phenomenon that I have never seen before in any literature so if anyone has any resources are open to hear more about this.
But isn't pressure in a fluid inversely proportional to its velocity? Shouldn't there be more pressure in the centre, where the fluid is at its slowest?
A.k.a.: imho, the ball doesn't sink because there is less pressure in the centre rather than on the sides, although that could explain that anyway through a reduction in Archimede's force due to the lowered pressure
Also, I don't think atmospheric pressure has anything to do with it, because once it is underwater it can't affect it, but I haven't seen the full video yet. Might cancel the comment.
Edit: I was wrong, atmospheric pressure plays a role, but I still don't think it works like you said. When it's completely sunk there is no way for the air to push it down, since it doesn't make any contact with it.
Also if there isn't a hole in the ball, is there air pressure in the ball that stays the same and could that potentially lead to it rising as well?
@@Anankin12 have you learned physics? In what class are you?
I thought the ball would go down for the same reason your helium balloon goes in front of the car when you drive. eg the water is heavier than the ball and will move toward the wall faster than the ball who get pushed center. With less force pushing the ball upward the ball sink. As for the ball going up I agree with other comments about water vapor since your other videos shows that water boils at that pressure. For the same centropic reason the vapor is also pushed toward the center under the ball.
The type of 'spinner' you used has a serious effect on this experiment. The agitator at the bottom, is in effect, a sort of centrifugal pump. Water is constantly being flung outward at the bottom, then forced up the walls of the container and flowing back in toward the center (all with considerable tangential flow as well). (this is why this type of 'mixer' is so often used, it circulates the fluid both tangentially around the container, but also radially outward, upward, and back down in the center)
This downflow in the exact center, IMHO, is what drags the ball below the surface. After all, when the ball is completely submerged, the air isn't acting on the ball at all. As others have pointed out, as the water spins around it also has centrifugal forces acting on it, so the surface of the water is always perpendicular to the combined centrifugal/ gravitational forces acting on it.
It would be very enlightening to use a different mechanism to 'spin' the water. For example, remove the agitator and spin the entire beaker. With all the water spinning at the same RPM, you would not set up the same internal flow pattern. The water at the bottom would not be 'pushed' outward to the walls of the beaker any more than any other water, so there should not be any 'vertical' circulation. Edit: Without this, I predict the water will form a parabola, but the ball will not be 'sucked/pushed' under the surface (much like you saw it under the high vacuum condition).
"spin the entire beaker... I predict the water will form a vortex in the middle" - it won't create a vortex funnel. It will form a concave parabolic surface. Like liquid mirror telescopes.
I trust u cuz have big words
@@col0342 would you care to elaborate that for me please?
I think your explanation with the centrifugal force makes more sense; isn't the pressure what causes the water flow not otherwise?
@@sangnguyentan1911 I believe he's referring to the shape the water surface would form if you spin the entire beaker as I suggested.
Near the very center, with centrifugal force very low and gravity, the shape of the surface would be nearly a flat plane. Only as the radius increases does the centrifugal force become significant and then the surface curves upward.
This is exactly how a mirror for a reflector telescope is started. The final shape has to be ground precisely, but the basic concave shape is formed by 'spinning' the glass while still molten.
ACTION LAB!!
ACTION LAB!!
ACTION LAB!!
Let the legend continue
Yo
@@TheActionLab how tall are you? 6Ft?
One of the first and hi
@@TheActionLab i think it was floating a bit because the air was getting pulled from the water so that force kept it up is what i think instead you should drop the Ball after a vacuum
very cool
Alternative explanation: the "air pocket" at bottom (under vac) is actually boiling water.
Yeah thats what i was thinking.
Also, im intuitively thinking it is the water flow that submerges the ball.
I think you're right. The water boils and dissolved gasses come out of solution where the pressure is lowest in the center of the vortex.
Consider repeating this with very cold water and see if the lower vapor pressure makes a difference. Or measure the temperature after doing this experiment with warm water. The evaporation/boiling may have already chilled the water by the end of the experiment.
Or repeat it with a fluid that won't boil. (Something with a very low vapor pressure.) That's all I have for now.
@@davidaustin3272 All good thoughts! Have I met a fellow chemist?
I swear one of those droplets of water hit my face when he was blowing the straw, so weird...
Quantum Entanglement with The Action Lab perhaps! ;D
Yeah its the iPhone x38
Drāno drain cleaner, lol
That is usually an effect people get
Parallell space hole?
You would need to also do the test with starting the whirlpool after the vacuum reaches least pressure for this to cover all the bases.
As has already been pointed out - Water boils under vacuum. The cooler the water is, the lower the atmospheric pressure needs to be to reach the boiling point. With a low enough pressure, tap water will boil at room temperature. Yes, that's a Fact!.
If you place the ball on still water and then pull a vacuum, the water will boil all around the ball like a pan of water on the stove, only the water will NOT be hot to the touch. As the air is evacuated from the chamber water will reach a point at which it boils. Right after this, the vacuum gauge will stabilize and stop dropping until all the water is gone, then it will drop to whatever level your pump is capable of pulling on your vacuum chamber.
In your experiment, the "air pocket" that formed under the ball while rotating the water is the water's gaseous state trying to reach the surface. This action creates a lifting force. The bubble formes in the middle of the vortex since this is the water's lowest pressure point.
Going a little off subject. Something else interesting about water is it has a "triple point". That is the temperature and pressure at which the three phases (gas, liquid, and solid) can coexist in thermodynamic equilibrium. Under the correct circumstances, water can turn directly from ice (a solid) to gas without first becoming a liquid.
Atmospheric pressure, Vortex, Effect of air movement
all covered in just 1 short video... Awesome!
Waauw Action Lab. You invented a simpel physics-setup that causes discussion among physicists! I envy you! I have my doubts about your explanation, but I cannot come up with a better one (yet).
2:00 I'm just gonna add that centrifugal force is pulling the water outward causing a toroidal shaped circulating system. A vertical cross-section thru the centerline would show the flow directions to be clockwise on the left and counter-clockwise on the right side. That is why the water level rises when the spin starts. Oh, a little addition here. Forget air pressure. Gravity is pulling the ball down. Air pressure is a function of gravity. Low vacuum causing vaporization of water beneath the ball with cavitation. Water vapor evaporated off the water at low pressure is accumulating under the ball and creating a small pressure to move the ball up. All great videos.
Each of these videos is worthy of a 10th grade science assignment. I sourced and got inspiration for one of my assignments in the action lab video about heating up water by blending/stirring it. I conducted my own experiments and ended up getting full marks. Thanks for the effort and information put into these videos.
not sure if you meant that as praise or as an insult.
Lmao, I really thought you were roasting him.
Note that a mag stir plate is a centrifugal pump. Drip in some plastic powder, or some dye! The flow is down the axis, radially across the bottom, then up the glass walls. (But, what if the water is boiling at room temperature? Instead try ice-cold, well-degassed water.)
Man you constantly come up with original and interesting experiments. Happy to say this is not some pop science channel. Your really teaching lots of people obscure and interesting science.
It would be so much fun to have this kind of dad. Never gets boring
In the normal pressure part, is it really the pressure from the air that sinks the ball, or the fact that the moving water is moving faster below the ball than above ? Perhaps the high-pressure experiment will tell. In the low pressure experiment, the air vortex below is likely to be vacuum, and the ball seems to be just floating on the walls of the vortex. These are my hypotheses.
Agree. The velocity of the water below is faster than that above the ball, producing a downward force due to the pressure difference(in addition to the original pressure difference).
The ball is floating on the walls of the vortex.
Great experiment! Overall air pressure has no direct effect on the ball - it pushes it down (via water) as much as it pushes it up. But the lower pressure allows building of steam- bubbles. They gather in the middle where the pressure is low and they build eventually a vapor column that wants to go up and pushes up the ball. It would be interesting to see the experiment with slightly warmer or colder water...
Better do it with some liquid with low vapor pressure, like mineral oil.
Experiment starts at 4:15
ty
Thanks mvp!
That little experiment that you did with the straws also illustrates how carburetors work. As intake air flows at extremely high velocities into the barrel and through the venturi, it has extremely low pressure that sucks fuel out of the float bowl and into the intake to join the air rushing into the engine.
Carburetors aren't used on cars anymore; they're exclusively fuel-injected now. But carburetors are still extremely common on GA aircraft, particularly those powered by Continental or Lycoming motors.
Got my subscription box yesterday !! Bit late but hey, I am sure there were good reasons. It had more than I thought it would. Quality hoses, brass fittings, thread tape for fittings, 2 wrenches, a vac gauge, patch,sticker, pin, instruction book and experiment book ,box with marshmallows -balloons - shaving cream. I like it all. Hope the next one is a bit more timely but I am sure you all were making a great effort. Maybe you got more orders than expected or ?? Thanks..
Yes this one had some hold ups. They should be timely from here every three months...glad you liked it!
I like your videos to study English. But I like the physical concepts too.
Drink everytime he says: "lower pressure."
I’d die from alcohol poisoning.
He really thinks low of his viewers with 100 rehashes in a video. “Lower pressure, ok guys you get it now? Lower pressurezzzz”
@@ParaSheld Who said that you have to drink alcohol?
And also what amount?
@@lukmly013 I think he thought drink drink
🍺
I drinked evrytim he said those words n im not drink yet bud this is terrible grinking dame.
Hey I have to commend you on your awesome videos, I've learned a lot!
One thing I must offer up in this one is, in the first case, it actually sinks for two reasons. First, centrifugal force and buoyancy act outward instead of downward as with gravity only. Second, the mixer is a turbine. It's pumping, sucking the water down from the centre (where the ping-pong ball is) and throwing it outward and up the beaker walls.
A common statement of Bernoulli's principle, the well established concept that a fast moving fluid is simply at lower pressure than anywhere downstream, is false. The common diagram of two large pipes connected by a smaller straight section of pipe, with a manometer connected midway in each section, showing reduced pressure at different points, may indeed work as depicted, but it is an incorrect way to measure pressure in a moving stream.
The reason for the above is because of the effect of the boundary created by the measuring tube. The same effect is created by the trailing edge of a venturi, tending toward the suction which causes gas or droplet entrainment.
The correct way to measure pressure would be to have a pressure transducer surface flush and nearly indistinguishable from the interior surface of the passage it is measuring. This way there is no disturbance to the flow, and so the pressure measurement would prove independent of flow.
The diagram depicted above, applied to a venturi, with or without the correction last stated, would work as depicted because the measuring location is at a *_change_* of flow shape/velocity.
i disagree with you conclusion: the ball goes down because of the water flow.
when you reduce the pressure you boil the water and the tendency is the densest fluid go outward. this, then, creates a zone with water vapour instead of water, having less thrust downward.
think of the stirrer as a pump that sends water from the bottom back to the top and you will understand.
when the water vaporizes the pump starts to 'cavitate' and the total flow is reduced.
this only happened because the vortex widened at the bottom. with a taller vessel or wider ball or a fluid that wouldnt evaporate at this low pressure (some polimer maybe?) you wouldnt see this effect.
a test you can make to prove this is to fill the vessel to the brim with water and seal it. there is no air pressure and the ball will go down because of the 'convectional' water flow.
you could even make a hole in the top of the lid and vacuum it and as far as there is no significant amount of water evaporated to start forming a cone the ball will stay down.
I totally agree with what you are saying his whole experiment just doesn't completely make sense to my
Even I completely agree with you. For some reason I couldn't agree with the explanation even after showing a practical. I too think it's just the water flow and not the air pressure causing the ball raise
Agreed. Maybe he could try it without the ball? The shape of the dip did absolutely nothing until the water started to boil. Doesn't that need an explanation?
Or try it with a piece of polystyrene with plenty of holes drilled through, to let the steam escape.
and, watching again i noticed another point: the 'air' beneath the ball is not air but water vapour that accumulated down there because the ball diverts the downward water flow from getting in the center of the spinner. bellow and above the ball where are gases (the 'inner cone') the pressure will be the same (a pressure low enough to evaporate water) . in the wet part of the ball are where the forces happens: buoyance and drag find equilibrium with that 'amount' of ball.
the cone does not form by air pressure. it forms by inertia of the fluid climbing up the walls by the "velocity/energy" imparted unto it by the impeller, centrifuge forces and all that.
by making the vessel closed at the top and filled to the brim you prove that: the water returns to the top and fills back the conical cavity without having the chance to climb.
to see the flow you could add some purpurin or other solid particles.
Rafael Ramos da Costa boiling is not an other process, The ball is locked. Maybe there is something more than pressure going on, but simply boiling will not do from my perspective.
Stupendous visual at low pressures! Did you see that? the level of control of the ball height with pressure? Amazing
You're always able to explain what you're doing really easily and the subjects are fascinating. Thanks
"When water moves it creates a low pressure. This is because when water moves it creates a low pressure. We know this because when water moves it creates a low pressure. The pressure is low because the water is moving. When the water is not moving the pressure is not low. Blowing on this straw double proves everything i just said. Blowing on this clear straw triple proves it."
question officially begged!
[ note to many: "begging the question" doesn't mean what you think it means ]
Perhaps the easiest to grasp explanation of what forces are actually at work there.
@@andriyshapovalov8886 -- Sounds more like calling out the circular argument.
@@willi-fg2dh wow. no one else is supposed to know begging the question is misused by almost everyone.
@@willi-fg2dh you are drunk 😵
I’m so glad this channel exists ♥️
Yayyyyy I got a heart from Action Lab 😄
That was completely unexpected. Great episode!
And thanks for not being run-of-the-mill. You come across like a kid playing with his toys rather than a science teacher with a curriculum to fill. It's a good example to set.
The outcome of the experiment was unexpected, not that it was unexpected that it was a great episode.
Just being clear.
Right idea for the wrong reason: at lower pressure , the gas/water vapor bubbling out of the water will tend to collect under the ball. If that didn't happen, buoyancy would keep the ball where it was.
Hmmm...I don’t think you can attribute all of the air under the ball to dissolved air. It is not trapped under there like a plug. But I agree that this could be part of the mechanism. There is a lot going on here, there is water dragging the ball down due to no-slip condition at the surface of the ball. There is air/water vapor below the ball as you said probably pushing it up. There is air pressure above pushing the ball down that mostly goes away under vacuum. This is definitely interesting though
This is my idea too. I thought he will start the spinner under vacuum.
I have a hard time believing the air pressure could fully submerge the ball. The water would have to be less dense than the air in the ball.
I think it's the water flow. The vacuum allows the water to rise higher on the outside. With more water on the outside and no water in the center, the toroidal flow forcing the ball down is greatly reduced. Not only is the flow reduced, the surface are of the water contact is greatly reduced.
@Henrik Wallin But why is the water going down in the middle?
@@TheActionLab what temperature was the water and what pressure did the vortex under the ball start forming?
I am really into space stuff and I really like this video because it shows things we already know about gravity but on an extremely small scale that I never would have guessed to be shown on such a small scale. Tyvm for the upload.
Great experiment! I think the explanation needs some work, though.
If it's just the air pressure pushing the ball down, then how does the ball "know" about the air pressure when it is already underwater? The only way the air pressure should be able to "communicate" downward through the water is by changing the pressure at the surface, which would only increase the total pressure at every point below globally. For the ball to be pushed downward all the way, there would have to be a gradient in pressure decreasing from top to bottom, a reverse of the gradient that would be there from gravity alone (when there's no vortex).
So I think Joël Séguin's hypothesis is more likely - that air resistance friction slows down the vortex at the top, and those layers of slowed-down spinning water slow down the lower layers a bit less, creating a gradient in speed from top to bottom enough to allow Bernoulli's principle to reverse the gradient in pressure that the water would have from gravity alone. The air pressure would then only provide the initial push down, with the friction-slowdown gradient pushing the rest of the way.
Well I showed in a previous video that the pressure propagated through the water so it doesn’t matter whether something is underwater or not it still feels the lower vacuum. For example if I had a balloon underwater in the vacuum chamber And I lowered the pressure of the balloon with still expand in fact that’s what I did in previous video. There is probably an affect due to the dissolved air or water vapor under the ball also
Yes, lowering the air pressure on top of the water should lower the pressure of the water below, but it should do so globally. Thus, a change in air pressure alone should not be enough to make the net force on the ball in this vortex experiment, when it is already underwater, change from upward to downward or vice-versa (i.e. the direction of the pressure gradient should stay the same). Pressure-wise, having air on top should only increase the pressure everywhere below just like having some extra water on top (with vacuum above).
And my guess would be that dissolved air should have a negligible effect in this vortex experiment (i.e. not qualitatively change the experiment's result).
@@davidellsworth4203 I agree with you. It's not the air pressure that is pushing the ball downwards underwater. It's the pressure gradient. The same kind of pressure gradient that keeps the ball in the centre.
Velocity of water will be higher near the bottom(as the strirer is at the bottom) than at the top surface of water. So pressure will be lower at the bottom. Same way velocity of water is high at the centre(so less pressure) and the ball tries to remain in the center.
I'm sorry but there is no way I'm going to read all the comments above mine right now.
The 2 straws example is a great representation of how a carburetor works!
5:23 Correction, that is probably not air, it's probably vaccum or possibly "steam" from the dissolved air in the water.
Rarified air/water vapor
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@@appmicro Ok? :D
@@TheActionLab It appeared right after you see bubbles of dissolved air into the water. These bubbles got trapped into the vortex motion under the ball, and caused the ball to raise up. I believe if this air or vapor has some way to escape from under the ball, the ball would sink again.
It would be interesting if you find a way to remote control the stirring motor, and start the vortex after all air removed - including that dissolved in the water, or just stop and re-start it under vacuum to check my interpretation.
+ The Action Lab - I don't know if this is what causes the effect, but I spent a LOT of time boiling up multiple litres of agar in large conical flasks on heated magnetic stirrers. Thing is, you see the vortex at the top, BUT as it starts to come closer to the boil, bubbles start to appear. This actually helps us visualise what the liquid is doing.
The liquid is thrown out from the centre of the flask, and hits the walls, and is deflected UP the outside of the flask. Once it reaches the top, it spills over into the middle, still spinning. Once it is here, it starts to sink, replacing the liquid thrown up from the bottom, so that we have a notable downward flow. Could it be THIS that causes the "suction" effect, when it is in fact the liquid flowing from top to bottom down the inside of the vortex that forces objects down?
You're the closest thing we have to a 2000's version of the late Professor Julius Sumner Miller.
2 questions, 1- what about the air exists in the ball 2- what about the gravity
By the way that was cool to see desolved air is not boiling much in movement
Who loves The Action Lab even tho he clickbaited us a few times?
In which vedio did he clickbated ?????
@@peacefulexaulter2160 The video which he talks about Vanta black
Even his clickbaits are scientifically interesting.
@@Milkycookiez34 that is a few times for you?? a few?
What he never does is bait and switch.
It would seem to me, having observed your video as the pocket of air began to form under the ball (Thanks to the water essentially boiling thanks to your lowering the pressure -- and thusly the boiling temp-- ) that in practicality what was happening was you made a sort of pocket atmosphere, thanks to the flow of the water which actually prevented the air from simply rising out of the water like it would as if you just let it boil, which was actually exerting pressure that was fighting gravity as it built up under the ball. So it seems to me that the ball didn't rise because there was no air pressure to push it down, but instead the dissolved air from the water simply began to push it the opposite way towards the lower pressure of the vacuum! Nonetheless that is quite a fascinating phenomena you made!
_No swimming in the chamber orchestra_
(Does that even make sense?)
No lul
Yes. Do not swim in the chamber orchestra room because it requires the room to be filled with water and water is bad for wooden instruments.
Very interesting experiment!
But as you point out in your comment there is definitely more going on.
One place to start untangling it would be when performed under normal atmospheric pressure why the ball sinks completely below the surface?
When you demonstrated the same thing w/o the ball the air column reached the very bottom, but with the ball, the air-column only reaches about half-way, while the ball reaches the bottom.
I really doubt that the water above the ball is lighter, and also I'm sure they're both spinning with similar speeds (not sure which friction is higher water-water or water-plastic).
Another question - when performed under vacuum, and the ball is half-way between the bottom and the top, there are empty-columns both below and above it.
Are both these columns same level of vacuum (I mean there isn't some weird way small amount of air is trapped underneath the ball)?
Does the water in the straw rises up because blowing air above creates a low pressure, so the air in the straw goes out and rises the water up ? If yes, then why doesn't the air surrounding the straw replaces the blown air instead of the air inside the straw, just like the effect in the video of the table fan's back. I'd be glad if you'd answer. Not an entire video but just a reply would be more than enough.
PS. I still praise the day when I'd found 5his channel 😍. Just a few days to go to finish binge-watching all the videos of AL
uc_human If the idea is true, I think that they both do since there has to be some sort of equilibrium.
Instead of thinking about it like the air in the straw is leaving so it “sucks up” or pulls the water up, its more like the atmospheric pressure on top of the water in the beaker is pushing water down, causing water to go up the straw, like a mercury barometer. Normally pressure above the straw and above the beaker are the same, but when blowing air, the pressure above the straw is lower due to fluid air moving quickly (Bernoulli effect I think) so water is pushed up by the normal pressure air above the beaker
@@x4002 this sounds satisfactory. Thanks
You're blowing the air above the straw away, so it creates a low pressure zone. And water rises to fill it up. Like a burning candle in a jar placed in a bowl of water
I thought that it was osmosis and diffusion
This is the best video!!! I didn't expect that at all!!!! It made a full vortex even though there was an object there....
I always thought it was because of the centrifugal force of the water spinning it wants to move outwards and in doing so creates a hole in the middle
I think this is true as well.
I'm too
The ball is sealed. It's clearly a lot bigger when it starts to float but the density of the entire ball must be higher than than the "free" stuff around it. So it should sink even harder than it did before.
Nice experiment!
Would you try to use a colored gas (should it not harm the mechanism of course) with the vacuum chamber so we can see the air leaving and entering the system? This particular experiment would be much better in my opinion
Something just hit me: you are Mr. Wizard 2.0 without the kid cohosts. I'm guessing you're too young to know who Mr. Wizard is, but after watching you for a long while, now, this has dawned on me. Trust me, as a late eighties/early nineties kid, this is a compliment.
1:46 This sounds like dentist's tools. I hare this sound
You misspelled hate
h a r e h a t e
Very cool. I learned a lot. Never occurred to me low pressure is what causing the funnel
“Im gonna suck water by blowing air”
Starts spiting saliva
TH-cam decided to recommend that video today, 2 years after publishing.
The youtube (ro)bot finally understood that i am interested in such great discovery in fundamental physics.
1:22 I thought it was his saliva
Hahaha..
Haha
I could’ve, but that’s why he showed the clear one
Every answer raises a new question! Was that an air bubble you created under the ball, or did you inadvertently create a vacuum within a vacuum using the surface tension of the water combined with the force of the rotation to form a "chamber", with the ball acting as a draw? Would be interesting to see if the same thing happens with differently shaped objects like a disc, cube, or a cork; as well as without anything floating in the water.
Is it possible it was the water boiling that was raising the ball? The vortex would funnel the bubbles to the center.
interesting point of view there
zokyn well, he pulled a vacuum and I didn’t see it’s typical boiling effect so who knows.
This was the first thought that I had too.
It would be interesting to see this experiment done with a glass or clear plastic sphere done in a low to zero G environment. The ball should actually want to move to the middle center of the sphere. There should be a layer of gas bubbles that form around the outside of the ball.
that's also what I think
I imagine this situation involves gravity, centripetal force, surface tension, and maybe viscosity. Plus vapor pressure when the vacuum gets high. (Those alone are enough to make it hard to figure out, too!) Atmospheric pressure only matters in that it pushes closed the vapor bubble at the bottom. I don't think higher pressure will change anything relative to atmospheric. But congrats on finding some unexpected behavior!
15 views 27 likes 0 dislikes 17 comments
TH-cam is dizzy from the whirlpool
DinPlayz RBLX what 15 views 17 comments
How come a video have 15 views and 2 likes? HOW? and 17 comments even tho its still 15 views!
Tom Scott explains it very well in "Why Computers Can't Count Sometimes". th-cam.com/video/RY_2gElt3SA/w-d-xo.html
The Action Lab
The Action Lab
The Action Lab
Is the best channel on TH-cam.
Can you start saying "Okay, this is epic"?
Quan Fifa yes
Please yesss
Libtards REKT with FACTS and SCIENCE!
You can see clearer when it's clear! Love it! Also I thought that was an egg until he said "ball"
action lab: your explanation isn't accurate. it's more to do with liquid flow than atmospheric pressure. also you are conveniently skipping the fact that at very low pressure the water is actually boiling at room temperature
“Now you can see it clearer with a clear straw”
10/10 explanation
I think these conclusions are all mostly wrong and a little right. I think you will understand more if you dump a little glitter in the water.
I'm sure that someone probably mentioned this in the comments that I was too lazy to read. Water in a vacuum boils below room temperature.
Anyway, there are my two cents... I should probably check the upload date aswell but I couldn't be bothered with that.
Keep up the good work and have fun.
Great video. Just a reminder, all these are described by Venturi, bernoulli, coriolis....
I think would be a good idea to leave some references for people who want to go deeper. Again, great video, thanks for sharing
Very good experiment but you should find a way to start the stirer after all the air is vacumed, because I think ball rises due to the dissolved gases under it can't escape and creates a pressure upwards.
(This part of comment prior to vacuum chamber experiment) The downward suction can't be the result of the atmospheric pressure above the ball. If that were the case, the ball would sink some, but could go no deeper than just below the surface where the air is still touching it, but just barely. However, we know that is not the case because once the vortex starts, the ball goes well below the surface and sinks all the way to the bottom. My guess at this point is that the atmospheric pressure might help START pushing it down, but there will be a point where enough of the ball is submerged (call it critical mass, or an event horizon, or a point of no return) where enough of the ball is submerged that the water alone can act on it, and at that point the pressure of the moving water is lowered enough that the buoyancy of the ball is canceled out causing it to sink. The one part I'm not really sure of is whether there truly is an event horizon that must be reached before the ball will start to sink; it is entirely possible that the ball may start to sink immediately once the vortex is turned on. Of course, even if there IS a point of no return, where there is too much of the ball under water for it to remain on the surface within the vortex, I believe that point will ultimately be reached even in full vacuum. This is because of the funnel shape of the vortex. As long as the vortex still appears as a funnel-shaped whirlpool, gravity will ultimately pull the ball downward until it reaches the lowest center part of the vortex, and because the the conical funnel shape, once the bottom is reached all sides of the vortex will have contact with the ball, giving it enough contact to reach that point if no return causing the ball to sink. Even if the vortex does not take on the conical whirlpool shape in vacuum, the decreased pressure of the moving water may still be enough that the water pressure is below the threshold of the ball's buoyancy, which would still let it sink. The only way it DOESN'T sink is if the whirlpool doesn't form and there is indeed a certain amount of the ball that must be submerged before it will start to sink. Considering that the ball; sinks in three out of the four circumstances I've described, my prediction is a 3/4 chance that the ball sinks. Not to continue the video and see how accurate my hypothesis is.
(Interjection with video paused as you seal the vacuum chamber) Okay, you activated the vortex and the ball sank all the way to the bottom before you even sealed the chamber, let alone before the vacuum was reached. All of my previous predictions are now worthless as they were contingent upon the vortex not being activated until the container was in full vacuum. Since the ball is no longer in contact with the air at this point, the removal of air from the vacuum chamber should not affect the ball in any way. Because the stirring mechanism at the bottom of the container will maintain a constant speed even when the chamber achieves full vacuum, that means the water will continue to circulate at the same speed as well, so the water pressure will still be decreased by that movement. Since the ball starting from the surface in vacuum (and the question of whether it would be able to submerge in vacuum in the first place) is no longer an issue, that really only leaves two possible results. Either the vortex retains its whirlpool shape because the water is still circulating in the same way and the ball stays at the bottom, or the whirlpool shape disappears in spite of the water's continued motion due to the lack of atmospheric pressure but the ball still stays at the bottom because the movement is still decreasing the water pressure. At this point I am FULLY confident in predicting the ball will remain at the bottom. Now back to the video.
(This part of comment after the entire video) Okay, I can admit when I am wrong. Since this comment isn't actually posted yet, I could easily edit my predictions so it looks like I was right all along and nobody would be the wiser, but I'm not that kind of guy. I'm honest. And I'm curious. can you explain to me how the loss of atmospheric pressure affected the ball even when it was fully submerged, having no contact whatsoever with the air above the water's surface? I'm also curious why the whirlpool reaches the bottom when the ball is not within the container but fails to reach the bottom with the ball submerged while in atmosphere, but when it's in vacuum the vortex is suddenly able to reach the bottom again in spite of the balls presence. I am quite curious about these things, so I hope you can provide some answers. Oh, and I no longer need to ask you to find a way to repeat the experiment while finding a way to leave the vortex off until it's in vacuum; if the ball rose to the surface even when the air wasn't touching it, then it wouldn't be able to dip below the surface in the first place if the vortex didn't start until after it was in a full vacuum. I would be interested in seeing if the results remain consistent if the experiment were conducted on a larger scale (like a vacuum chamber the size of a room and a water container like a deep pool). Would the ping pong ball still stay on the surface at the center of the vortex? Would it float closer to the edge of a larger vortex? Would the larger vortex manage to pull it down where this small one couldn't? And what about different kinds of balls? With the larger vortex you could test several. Would a basketball float? How about an irregular shaped ball like a football? How about items even lighter than the ping pong ball? Would they stay low in the vortex or float higher up the side? How much mass would a ball have to have before its weight overcame its buoyancy within the vortex in vacuum? Would it require the same weight as it would take for a ball to sink in calm water? Less weight? More weight? So many questions! Of course I'm sure you'll never have access to a room-sized vacuum chamber, nor will you have access to a pool that would be the equivalent of that stirring container scaled up to be like ten feet across, so we'll likely never get to see those experiments. And I am also curious about the experiments you mentioned with increased air pressure, but that would pretty much necessitate a hyperbaric chamber. Although . . . The box of you vacuum chamber seals air tight. If you switched the hose around on your vacuum pump so t sucked air from the room and forced it through the hose into the chamber, then it would just be a matte of rigging clamps or belts on the outside of the box to keep it from bursting open (after all, it IS designed to withstand inequivalent air pressure, it's just that its current configuration is focused on the lesser pressure being INSIDE. Hmm . . . my creative building mind is percolating!).
Anyways, awesome video! I love these experiments!
The ball is still being pushed down. The reason it goes up is becasue of that bubble beneath it trying to escape.
The bubble is water vapour produced by the low pressure at the bottom (the reason the ball goes down) being less constrained by the pressure of the air. This is causing the water to vapourise in the centre.
You can see this happening above the ball as well, the difference is that below the ball the vapour can not escape. As the bubble gets larger it actually does escape several times in the video by getting large enough to 'bubble' around the ball, when it does this the ball does drop slightly each time. This indicates that the ball is kept up by the bubble.
If the ball had a small passage through its centre then the air would escape and the ball would stay at the bottom.
The ball moving down is not because of air pressure, it’s because the spinner acts as a pump. A pump has a low pressure side and a high pressure side. The low pressure side is the center and the high pressure side is the outermost part of the container. Water is being drawn into the center and pumped up along the outsides. The spinner makes a vacuum at the center of the container that is stronger than the buoyancy of the ball. When you place a vacuum on the entire enclosure, the relative vacuum of the spinner becomes weaker than the buoyancy of the ping pong ball.
And no, the water isn’t boiling.
It turns out that I am not good with science but I kinda like watching these kinda videos. Thank you for informing us.
1:00 Yes, the Venturi effect is a thing, but the reason the pressure is low there is because the flow is diverging at that location. Venturi may be present, but it’s hard to be sure without actually knowing flow speed there, which you don’t.
Woah man this is it, what I was trying for a month, Now I understood the behavior of Blackholes, Your video gimme direction for my next experiment...........Now I'm gonna try it in my Next Javascript program with pure visualization..........
I can see you being the coolest most interesting science teacher!
This is one of your better experiments, I thought it was good.
Many black hole applications with this experiment aswell! great vid.
It doesn't look like a game of pressure. From what I see with this experiment is that the volume of water level remained same whether the ball was inside or outside. It seems that extra empty volume created below the ball kept the ball up. Since the volume below the ball may not be air due to vacuum chamber, it means there is simply not enough space for ball to sink in the water. Also because the air is sucked out, the density of water should increase which should also contribute for ball to remain up in the water. Can we do this experiment with just the water(without air)? This is definitely centrifugal force which created low density area in the center of water but when we removed the air from water, the density was increased again and ball moved up.
6:55 One unit of atmospheric pressure is completely arbitrary, so if lower pressure causes it not be pushed down as much, then yes higher pressure means it's pushed down more. Pretend we consider 0.5 atmospheres to be "normal", so you did your experiment on the range of 0.1 - 1 atmospheres, up to twice "normal". In the range of 0.5-1, you noticed "higher" pressure pushing it down more.
Assuming you can create a vortex in a vacuum the ball should sink down slightly at the very least by way of being at the center of a funnel whose walls are higher than its center. That might be worded a bit awkwardly, but put it this way: it’s going to be on top of the water, but the water level needs the center will be lower than the water level on the sides.
you deserve two thumps up for your effort to make this video.. nice job sir..
Good job, dude! You're on your way to understand how gravity really works. This is "centrifugal gravity" =) The water doesn't "suck the ball down". The ball actually falls into low pressure zone. Now think the same thing but to centripetal process... Then you'll understand how planets "attract" each other. And how parallel conductors "attract" each other. When actually they are just being pushed towards one another. All this is just an Energy conservation law explained with Bernouli's equasion.
Any weight difference between air atmosphere and vacuum chamber ?
I like to see whirlpools and you just rediscovered it for me!!
The impeller at the bottom eventually creates cavitation and a little bit of boiling occurs as well. Even though inside the box is almost complete vacuum, the water still creates pressure as you go deeper, but the pressure is lower now and cavitation occurs easily. However, this phenomenon makes the ball sink not rise. But the water around the ball still creates pressure and pushes it up.
When the pressure inside chamber is high I also think it causes the ball to go down to the low pressure created by swirl. Also the explanation using molecule motion and forces is equivalent to an explanation using fluid dynamics and pressure but the first one is at a more fundamental level. For example the flow of a liquid creates low pressure around it because the molecules near the edge are hit by the moving ones and the volume around is depleted of molecules so new molecules come to occupy the place and so on.
Water boils in a vacuum so it wouldn’t work, and whirlpools generally have a down current, air doesn’t have that much pressure on the ball compared to the water.
*This is like learning science!*
The rotation movement make an incredible absorbtion force.
When you remove the atmosphere above the vortex the vortex would have to strengthen because of the pressure gradient force, therefore the ball gets pulled upwards. That’s the reason why tornadoes are so intense, because the internal pressure falls within the mesocyclone (above) are so intense that it pulls upward and stretches the vortex vertically and strengthens it.
Hydro dynamics with a hollow ping pong ball.
The stirer is pushing the water to the sides and goes up the cylinder, and what goes up must come down, the waters surface tension is grabbing the weightlessness of the hollow ping pong ball, is pulled down by the water returning to the bottom of the cylinder which make it act the way it did
I almost watch your all vids! I also want to be a scientist, u inspired me a lot!
I wish i have a dad like you🥺
Water is essentially incompressible at these pressures, little if any volume change. There is a pressure gradient in the air above the rotating water column.
Very nice. Thanks for the lesson. Now I know how my airbrush works.
The straw experiment ( like a draft in chimney) is like there is a static rest connection with a vertical column of air and a continuing column of water directly beneath the column of air .So that when a section of that column of air moves away from its rest position the connected column of water wishes to stay with that moving air it was associated with .The whirlpool experiment water is pretty much incompressable The ball then is being aided by a force that is pushing the water back so it can descend As in the vacuum this force stops it must be air There must be a very thin layer of air between the ball and the inside wall of the whirlpool holding back the resistance of the water pressure to let the Atmosphere push the ball down
There are so many scientific research going on on so many channels.
It's amazing. When will it be so much that people can't think of new stuff.
The Action Lab is the Knoff Hoff Show for generation TH-cam
I love your channel but this is by far my favourite and unexpected visual sensation
wow how awesome is that, yes, l want to get the subscription boxes
You aptly demonstrated the Venturi effect which makes a carburetor work.
I don’t know how I keep ending up on these vacuum videos. I’ll have to subscribe one of these days
Partly true, the starting point of everything is when a positive charged spinner is in a negative charged jar of water, the water is chasing the spinner around which is creating a vacuum for the air to full into.
Again, I always learn something watching your videos, even though I'm 50. Please keep it up!
Initially my thought was same. Water drag. Really informative videi
This is the kind of video you have to watch multiple times just to meditate on how basic everyday physics works. I didn't quite understand a lot of things until now.
It's interesting, the different interactions between liquid (water) and air/vacuum, with gravity being a key ingredient. When you lowered the pressure in the chamber, you sucked out all the air, but not the water. Gravity was too strong to do that quickly anyway. However, you induced evaporation/boiling in the water due to the low chamber pressure AND the even lower pressure from the spinning in the center of the beaker. That's really interesting and it seems like some kind of mechanical computer could utilize these facts to make a sort of water-transistor or something.