SmarterEveryDay you both talked about how storms rotate based on their hemisphere. what would happen if this storm crossed over? or does this just not happen
Chris Bowe that's a good question and I'd actually like to know the answer, maybe one of these guys will make a video about it. It's so nice to see someone actually asking a question for the sake of curiosity in the UA-cam comments for once! Props!
The structure of these videos so they work best when played simultaneously is actually awesome! I never watched either of them but watching this is just so cool how you take turns speaking and the video is set up so that there's always something to be looking at- it's just so immersive I feel like I don't have even a second of idle thoughts before something else happens but it's also not like it's an overwhelming onslaught of information. It's just so we'll made to keep the attention of the viewer
+Black Fedora The two countries where the experiments were undertaken and therefore relevant to the experiment and Jimmy Greys comment - namely Australia and the U.S.A.
From what I've seen, the Anglophone countries tend to be somewhat mixed in their usage of imperial vs metric. In America, while using imperial mainly, most still know the metric system and it has some common occurrences, such as using liters often. People in the UK, while being mostly metric, have occasional thing that are referred in imperial.
The UK is a very mixed bag indeed. A person's height, weight, waist size, etc will always be quoted in feet, inches, stones or pounds (regarding weight, it is near universal to quote stones and pounds rather than just pounds) - conversely in medical practice all of these must be recorded metrically. Many people also know their weight in kilograms, but it's rare indeed for them to express it that way. Groceries and indeed most consumer products will be expressed metrically, with the exception of beer which are almost exclusively sold as pints or half pints, milk is labelled both metrically and imperially, British people will however always refer to it imperially. The situation is more complicated for motoring. Distances and speeds are still in miles and miles per hour respectively, most British people would also be able to refer to directional distance in yards or metres fairly accurately.Fuel is sold in litres, but fuel economy is miles per gallon. Engine size is in litres or cubic centimetres. In my experience I think it's fair to say most British people 'think' in imperial terms though are quite happy using metric measurements or expressing them if required to do so.
Yeah, it's hard to deny that if the British didn't hate the French that much, we'd be universally using the metric system today. The British came around eventually but not before leaving themselves and the rest of the colonies in a dismal state regarding units.
I served a mission for my church in Brazil. One of the first things I tried, was fill a sink with water, let it sit over night, then pulled the drain plug with a string, rather than reaching in. It indeed swirled clockwise. I tried it several times with a sink behind the house, that is normally used for washing cloths. It too drained clockwise. The toilets were no indicator, since the offset jets determined the direction of the vortex when flushed. I was in Minas Gerais, which is far enough south, to make it pretty reliable as long as the water had time to completely stagnate. I even placed a board over the outside sink, to make sure no wind could disturb the water. If you drained the sink immediately after use, any turbulence in the water would override the effect, and it would swirl in either direction, It didn't take much, to influence it.
It's interesting to note that at the level of a tornado, which is considerably bigger than a bathtub but still pretty small on the scale of the Earth, about 95-98% are said to rotate cyclonically (counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere), but there is that small fraction of anti-cyclonic tornadoes.
Yes, I've heard of these "reverse" storms, but I never saw a percentage given. At a hurricane level, there has never been a "backwards" example in all of human history.
@@kdwaynec Cyclones (hurricanes in the southern hemisphere) rotate clockwise. All the science websites say its due to Coriolis effect. This experiment wasn't needed. If all tropical cyclones/hurricanes rotate counterclockwise in northern hemisphere and all cyclones spin clockwise in southern hemisphere, i don't see why there'd be any doubt.
@@burtan2000 0) Because it is an incredibly small effect for a pool that is 6 feet across. The physicist who originally did the experiment was somewhat surprised that it worked. Why do it? 1) Because it is cool to do. 2) Because replicating results is what science is about.
Jack 64 I’m pretty sure they are both American. The way Veritasium said Australia sounds very similar to how I hear a lot of Americans say it and he also said near the beginning “in the other hemisphere” and “when I was in Sydney Australia” which would be the sort of thing someone from the northern hemisphere would say
@@mission101 veritasium is Canadian and he moved to Australia Edit:to clarify, he was born in Australia but lived here for a very short time before moving to Canada with his family until he was old enough to move out when he finally came back to Australia.
but the Simpsons was wrong, Lisa tells Bart the toilet and sink are due to the effect but like this video says the effect is overcome by the design of the toilet/sink
No it is based on how the basin, or in this case how his pool was setup. The shape will determine which direction the water flows. Nothing to do with where it was located. People are fooled so easily!
@@skyisthelimitreadyornotfor2 Sigh, repeat the experiment yourself. Do it a 100 times, re-building the setup equipment each time so that you eliminate that "how the pool was setup" effect. Take a look at the results. I bet 99% of the time you'll get the same result.
You might get more consistent results with a very long pendulum (Foucalt's pendulum), but that would be more expensive to constructs. There is one in my city and it is built into a tower so it is shielded from weather. The pendulum swing is steadily altered by the Coriolis force, which can be observed by a pattern drawn by a stream of sand coming from the pendulum weigh.
More important that is not the question. The question is about liquids. This remembers me when students do all the calculations properly on a math exam and then forget that the question was about the diameter and not the radius of the circle
@@crownnothin - "False. If you see a crane when it's not working the ball on the end of the line does not move and its way bigger than a display in your city." Cranes that aren't working don't leave an unburdened line all the way down, lol - they keep it hoisted to the top so it doesn't like, break things, or itself, when not in use. The other problem is as they mentioned above, if you hang a line outside it'll have things like wind pushing it around. An openly swinging crane line isn't going to show the Coriolis effect because it'll be swinging in the wind (hence, they don't leave them hanging when not in use), which is why the Focault's pendulums are built in towers so they can be shielded form the weather.
@@KingBobXVI > which is why the Focault's pendulums are built in towers so they can be shielded form the weather. Yah, my high school had one in the atrium of the "science silo" -- a round wing that contained most of the science lab classrooms. (There was a fad of building science classrooms like this in the 1950s and '60s.)
I once cut the base off a 5 gallon drum, wrapped copper wire around the neck and hooked it to a car battery. When I switched it to positive it increased the up the spin rotation and when I hooked it up to negative it just went straight down. I don’t remember how well I controlled the experiment to not have any motion in the water prior to pulling the plug. However, the effect that the positive and negative electric current had was repeatable.
I don't dispute the explanation of the coriolis effect, but I have to question whether the speed difference over a couple meters is significant. (Distance from pole to equator 10M km, speed at equator 460 m/s, therefore each meter represents an average change in speed of .00005 m/s per meter.) This experiment could easily just be a fluke. Before jumping with joy, I think multiple better controlled tests would be needed.
this is why they said that the effect is so minor that in general, it gets lost in other factors that influence the way the water drains. the moment you throw in any disturbance to the water before the water starts to drain will alter how it drains WAY more than the rotation of the earth.
+Ursinos I am aware of that. I have discussed this in another thread, and there I even stated : "The paradox of my criticism is that if everything were perfect I would expect the result that they got. I just don't believe that they proved it." And there's the rub. The effect is so small that I'm not convinced that this experiment can eliminate other factors that influence the way the water reacts. Even convection currents due to where the sun is shining could be a larger effect. But my position may be weakening. In that other thread someone posted this reddit thread : www.reddit.com/r/IAmA/comments/38gekk/iama_guy_who_makes_science_videos_on_youtube/cruudik
They repeated it 3 times time though, and still same results. So this happened: 1) the results line up with their location 2) same results 3 times. What's the chance to have it by accident? Should have tried with different pool setups/at different times (day/night) though to be 100% sure.
Yan G yeap, that would be the very minimum to ensure there are no other effects at play (or even slight variation of the pool shape). Even then I'd bet the results would be close to 50-50. After all it's a chaotic system and the scale is *far* too small for the Coriolis effect to actually matter (at larger scales we already know it does). Oh, and waiting for 24 hours for any initial rotation to settle is ridiculous. I have no problems with the video other than it implies this is proper methodology.
As a physicist, I'm still dubious about these results. Of course the Coriolis effect is real, but let's do a little math to quantify how much impact it should have in this experiment: Huntsville, AL is at a latitude of about 34.7°, so that means that an east-west circle around the globe at that latitude has a circumference of around 40075*cos(34.7) km, or around 32947km. If we assume that kiddie pool has a radius of about 1m, that means that the northernmost point in the pool is about a 40 millionth of the way around the globe from the center, or about 0.000009 degrees. We can calculate the difference in distance around the globe at that slightly different latitude: 2*pi*(6371*cos(34.7 deg)-6371*cos(34.7000009 deg)), which says that the water at the far north edge of the pool will travel about 350um less than the water in the center (and the water at the south end will travel that much further). So if it takes the pool, say, one hour to drain, that's a total difference of about 15um of travel between the water in the center of the pool and that at the outer edges. 15um! That's 1/5 the diameter of a human hair. And that's over the course of an hour. I really doubt that's enough of an effect to set the drainage direction in motion.
This was an interesting experiment, but I'd really like to see it repeated 50 or 100 times, perhaps with even longer times between fill and drain. I'd guess the 'success' rate would be in the 80-90% range, perhaps more.
I think the geometry of the drain can also create vorticity, as in case of the wings of an airplane, the no-slip boundary condition on the surface of the wings is a source of vorticity even in previously irrotational velocity fields (see for example the Kutta condition). What I mean is if you have a drain formed as a Kaplan turbine for instance, even if the turbine is standing, the flow will begin to rotate automatically and that is not becouse of the Coriolis force.
I just watched this and the first thing that popped into my head was any irregularities in the drain, the bottom of the pool that water is flowing over, or even the direction the ball valve opens could start the motion in one direction.
Further exemplified that the rotation happens at the drain itself. Simple scale analysis shows that Coriolis would not be affecting the water at this distance.
@@grillmaster95 You would only see the Coriolis effect at/near the drain as the reduction in radius is needed to markedly increase the otherwise very small difference in angular velocity of the water going around the outer edge. Coriolis effect on this scale is tiny, but when you have a radius reduction on the order of 50:1, the magnifying effect it can have on angular velocity is rather extreme.
Actually making this happen would be a problem as the larger scale rotation of the wind would be pushing the tornado away from the equator. But lets just assume for a moment you could then no the tornado still wont collapse it's not the vortex rotation that's driving it it's the atmospheric inversion (The fact that warm air high pressure air is trapped bellow cold low pressure air). So long as the inversion remains the tornado would keep going though it's vortex should begin to slow and even eventually stop and start going the other direction if it lasts long enough which is pretty unlikely it has some pretty significant momentum and they just don't last that long.
Brian actually, tornados are too small to predict their rotational direction. On this small a scale you need really calm initial conditions to see an effect of coriolis (like they are in this video - they let it sit for quite some time and then don't even dare to simply pull the plug) you don't have such conditions in the free atmosphere. It's different with the much bigger hurricanes. They rotate ALWAYS in the direction dictated by coriolis and can't exist near the equator (between ~5 degrees north and south) due to the lack of coriolis force. So yes, a hurricane would break down but no, a tornado wouldn't.
I agree with Eleanor. I think Veritasium headlined toilets mainly cos it's kinda smutty, even though the vid itself is excellent in my opinion. I agree with Filip that size is important. Not just the size of the body of water but also that of the drain hole, take a look at Google images of reservoir drain holes, where the surrounding water doesn't appear to swirl as it goes straight down the sides. I suggest elsewhere it's the interference caused by a narrow hole that results in swirl in one direction or another.
I have physically experimented with it. A pool a few meters across could be made to swirl in different direction by manipulating it a bit. But if in sizes of several kilometers across, the earths rotation would most surely be the dominant factor.
The experimenters in the vid took a lot of trouble not to manipulate the water themselves, by leaving it to settle overnight, and draining it with valves located outside the pools. But I guess you're saying the pools themselves are still far too small to convincingly show up the earth's rotation effect. What do you think of my point about drain hole size as a factor in swirl, leaving aside the question of direction for the moment?
I don't know but I believe the drain hole is an important key to the rotation in small pools. But someone should run the numbers on this, cause I really wanna know.
Coriolis effect does exist but only noticeable in larger scales such as wind patterns. In the case of this experiment, there were still many factors such as the sizes of the drain, valve direction, small creases on the bottom of the kiddy pool that may diver the water heading towards the drain in one direction in a molecular level. Furthermore, a proper experiment would've included multiple attempts in similar conditions. One guy did it outdoors, the other did it indoors, and each person used only 1 pool and only did it once.
It is about size. The bigger the pool, the bigger the Corriolis effect. If the pool gets to slow, other factors like micro currents, friction, air draft, the shape of the container etc will determine the rotational direction.
I literally posted both of the old videos yesterday, when someone posted to fb a video where people walked across the equator and supposedly proved the coriolis effect, but they were pouring the water in the complementing directions. People were saying, "Mind Blown!" and other ridiculous exclamations, and I just sat there wondering how I could tactfully tell them it was a trick. Thank you for combining the videos!
Viola James good :) Yes, so often people miss the key factors. Could include myself as well, in some topics I don't understand so well. I'm also happy this video was released. I had been wondering if it is true or not. This confirms it pretty well. I mean, to me it looks valid. It may not be scientific as a test (two) arrangement, but it is at least a good effort and well explained.
LiacosEM demonstrated this can work with just a cylindrical container with a hole in the center provided you let the water settle first and remove the drain plug from below. The cylinder was only about 10 cm diameter.
This video and experiment are great! But, as with most scientifically focused videos, too many of the comments leave me questioning the future of humanity.
You guys have the BEST video on this question. I "seemed" to observe that the water drains from my Canadian tub in one direction one day and another another day, so I needed the science.
Great, and thank you! Every physicist knows this, but there are so many counter experiments with additional forces involved. It's the Coriolis effect, or Fouceaults pendulum if you like. Wonderful video, and clear victory for physics. Added it to my favorites and physics lists.
If you go back to their example with the pool at the poles, you should be able to figure out what would happen if the pool was moved further and further from the equator. When the pool is at the equator, the water on either side of the drain would be moving at exactly the same speed as the drain, so as the water moves closer to the drain it wouldn't go ahead or behind, thus no rotation. The pool would just drain straight.
My thoughts ! in science a proof is something reproductible, so ... That would be a bit of a waste of water, but I expected it to be done at least twice
With Coriolis is not a matter of length alone. Velocity is inportant too. I was surprised as well by the small dimensions of the pool but the water is flowing very slowly. I'd like to know the Rossby number which will give you the importance of Coriolis forces over inertial ones...
Very good video, well done guys! I’m just wondering why you didn’t add the dye before opening the drain, maybe wait the same time you deemed the water had no spin then add the dye, wait a few hours to ensure no motion and then open the drain? But the video is great! I really enjoyed watching and I feel richer now 😊👍
If you add the dye before opening the drain, it dissipates and you can't see it, and/or you introduce motion to the water before the effect can start. Adding it after it starts, allows the water to build its own momentum first. A few drops of dye isn't going to change the direction of kilograms of water that's already moving.
I’ve actually seen this effect demonstrated by the equator in Ecuador. Same basin on legs with drain into a bucket underneath. They added flower pedals to see the motion. They did it about 20ft north of the equator and then picked up the basin and repeated the same experiment 20ft south of the equator. They effect is still apparent even that close to the equator.
Are you sure they weren't cheating somehow? I think the effect is effectively zero near the equator, as all parts of the pool are at very nearly the same distance from the earth's axis.
@@andersmusikka one might think. I know I would. I saw it with my own eyes. They used the same basin so the same constants on both sides. It was more of an educational demo as opposed to a magic trick.
nah, make sense on a flat model as well. The rotaition could be the Sun, travelling over the equator. Everything on the left would gain a small pull on their right side. Just like a passing ship, causing turbulence on each side, with opposite water-spin-direction. The effect might be proven, but is the spin too? Maybe we can try it with technology of our century... just wondering.
Sortaray flat Earthers surely can't believe in the mass to gravity correlation, right? Because what the hell is under the flat earth? Infinite mass?? 😂
Too cool! Coririolis rock! The Earth rocks! You guys rock! Well done. I FINALLY got hub to understand this principle (I’m a MSc in applied mechanics/combustion engine engineer/ and he is an archeologist). A million THANKS 🙏 to both of! This version (showing both besides each other) was very pedagogical.
That's a very interesting video and one that has left a few questions in my mind. If the water were to emerge INTO the pool from the hole in the bottom, do you think it would begin to turn counterclockwise in one hemisphere and clockwise in the other? I'm asking because weather events are made up of either an ascending air mass or subsiding air mass. When the air mass is subsiding it moves along the surface towards the lower pressure area away from the center. When the air mass is ascending it moves along the surface towards the low pressure in the center. Therefore I'm wondering if the water were to move away from the center of the pool would it rotate the other way?
Probably not. Two problems. First, Your in-flowing water would start out so turbulent that it would completely overwhelm any Coriolis effect - it obviously hasn't been sitting still for any time at all. Second, pumping water in from the center you'd get an angular momentum DAMPING effect as the radius of the pool increased, as opposed to the angular momentum exaggerating effect that you get when you reduce a radius. The Coriolis effect is already incredibly minute at these scales, so you need the reduction in radius in your experiment to make it visible at all - going the other way would make it impossible to detect.
seasong There would be 100% speed difference as it would be going the same speed in the opposite direction Edit: angular velocity or whatever, not technically speed
This effect is caused by the difference in linear velocity around the axis between two positions with the same angular velocity. That difference is caused by them being at different radii from the axis. Distance from axis on the surface of a rotating sphere is proportional to the sine of the angle from the pole. The greatest difference in linear velocity will occur where the greatest difference in the sine of the angle is. The angular size of the pool being constant, this will be where the gradient of the sine graph, dsin(x)/dx, is at its greatest. dsin(x)/dx = cos(x). cos(x) is at a maximum where x = 0. This effect will be strongest at the poles. Further, cos(90°) = 0, so at the equator there'll be no effect at all.
I appreciate the effort you have gone to to undertake this experiment, however, for this to be scientific, it must be repeatable. One single result doesn't prove the existence of the Coriolis effect on this scale. It could have simply been a coincidence. There are factors which could affect the direction of drain rotation more than the Coriolis effect in day-to-day life. It's like the butterfly effect, tiny influences in the initial conditions can change the results dramatically. The wind direction, convection caused by sunlight etc. Possible improvements: Covering the pools with perspex and a cut a hole in the top to let the air in. Put the pool under a gazebo to shade from all sources of light. I would be interested to see a follow-up video of the experiment repeated several times.
It would be interesting to include a discussion of the great air masses (and some currents) flow in the North Atlantic (clockwise) and South Atlantic (counterclockwise), the opposite of what is shown here.
A long time agi I worked in a laboratory that studied airflow in buildings. We had a symmetrical air room there where we could measure air speed through the entire room which was blown evenly from one side in that room. We noticed this effect as well. We had not enough data to prove anything, but interesting it was.
@@candyneige6609 in the USA and some parts of the northern hemisphere the storm is called Hurricane and in the middle which is the Equator its called a Typhoon in the southern hemisphere however its called cyclone like in Australia
Fun fact : Due to the coriolis effect, the hair on men's is swirled in different direction. You can look at their occiput and see the direction will vary depending on which hemisfere you are or on which hemisphere they've been living
Wondering if, when you repeated this experiment, you completely rebuilt and re-leveled the base of your pools or even used completely different ones each time. As from what I understand of the coriolis effect, your pools are far too small and would drain far too quickly to be significantly affected by it. I think what you got was fairly lucky and not a repeatable result. Would love to see someone actually do the math on it.
It depends on how the water begins circulating into the plug when you pull it. You can make the swirl go the other way. Some outlets are not so symmetrical. This will cause the water to drain in one direction most, if not all the time. When drains are manufactured, they may all drain the same way.
veritasium, I have a question that none of my teachers have been able to answer. We know that photons are the particles responsible for the electromagnetic interactions and that they have no mass. So what is it exactly that we feel when we hold two magnets with the same pole near to each other? What's exactly happening between these magnets? I would love it if you made a video about it! -thank you
I believe the answer lies in exchange in momentum due to exchange in virtual particles, try to find out more about virtual particles, I don't remember much myself so I can't give you a detailed information.
You learned a more valuable lesson than why the magnets feel force. You learned that teachers don't know much, which is why they became teachers, and not something better.
This is a really tricky concept that takes a lot of knowledge of advanced physics to understand. As a college sophomore I know just enough to see how complicated it is. A gross oversimplification is that it is due to relativity and quantum mechanics.
The rotation, in which the galaxy (if it's a spiral galaxy) swirls is completely random, or it can be influenced from the existence of dark matter, which is confirmed to surround every galaxy, including our own Milky way, or the rotation, in which the central supermassive black hole spins. Rotating galaxies take shape of a spiral, because the closer are the objects (stars, nebulae) to the galactic center, the faster their rotation is around it. So the whole body of the galaxy starts to bend into a spiral. However, then it gets weird here. The dark matter, which is surrounding our galaxy - it firmly holds it all together. The stars which are orbiting the galaxy center further than others are orbiting it faster. The rotation curve, which should be decreasing with the distance from the galactiv center actually stays constant throughout the entire radius of our galaxy. Dark Matter, whatever it is, is weird.
They forgot to mention that there is a pocket of air that forms underneath the drain hole, on the inside, where it cannot be easily seen, that pocket of air causes the water to have to push past it because the water cannot push the pocket of air down, it can only flow around it. The pocket of air is what causes the water to drain out so slowly. If you take a simple drinking straw and push it down towards that pocket of air, all of the water will, at some point, rush out of the sink very very fast! The reason is simple: because that pocket of air can suddenly pull air from outside of the water swirling down into the drain! It makes an enormous and very loud sucking noise, that pocket of air is why fluids drain so slowly through even a large sink or basin. The water can rush out of a steel sink fast enough to cause a slight contraction in the bottom of a steel sink, which can be heard as it rushes out. I've done this myself, that's how I know it works! :D
Wouldn't the Coriolis effect be negligible on such a tiny body of water? I'm no math wiz, but I imagine the differences in velocity between the sides of the pools nearest to/furthest from the poles would be so tiny as to be nigh incalculable. Seems like a factor as small as the pools' designs and how level they're sitting would do a lot more to influence the outcome than the Coriolis effect. We'd need to see this experiment done numerous more times with less imperfect conditions in order to confirm this definitively.
Dye is not a variable in rotation. Wind, possibly. Depends on if it was windy. But these are pretty smart guys. I'm sure they took wind speed into consideration
Water always flows towards less pressure. If the hole in a sink or a bathtub is just a little off center, or the tub is tilted just a tiny bit, or many other factors in production and installation, then the water will change direction. This is easy to prove in the shower or the bathtub. Just put a foot besides the drain, then the water goes one way. Then move the foot to the other side, and the water change direction. This experiment is ok because it is a large surface, and the water is very calm, but in a toilet you can not decide this because the water is turbulent and coming from above with gravitational force, and the design of the toilet is random.
Hey, let's be somewhat sceptical about this, you have done this only once on each hemisphere, so there's still 25% chance that the effect is completely random xD
Yep. It should be done at least 5 times each. Not that I'm doubting the result, it does make sense, but any scientific experiment should be repeated to ensure that the result is not just random.
The effect is real and is called the "Coriolis Effect" after Gaspard-Gustave de Coriolis (1792 - 1843). The magnitude of the effect increases the further north or south of the equator one goes.
A scientist, and an engineer, both describing the same thing differently with different words. It is a beautiful thing. Education is what lets you get that. Learn the words people, so you don't become internet stupid.
Do you sit on the toilet or do you stand? In developed countries the toilet is mostly the cleanest place in the house due to constant desinf. And the water is dringing water mostly.
Little known fact: If you drain a tub EXACTLY on the equator, down to the millimeter, the water won't swirl as it exits the receptacle. It will rush-out like a circular waterfall. Though, in this case, when I say fact, I mean totally lying.
JGirDesu he had 2 sinks on each side, each one went a different way, yet the drain went down the middle then in between them, connecting them. | | ----- | |
I think both sides of this dispute are null. The first hypothesis is that the direction in which the water swirls is either clockwise or counterclockwise, depending on which hemisphere, due to the angular momentum of the earth and the Coriolis Effect when no outside variables are present. The second hypothesis is that the effect does not affect the system enough over such a short period to overcome outside variables and thus does not reverse the clockwise or counterclockwise flow of the water. The argument is "If I eliminate the variables that cause the effect to be false, it is then true."
That's great, BUT ...at my place in Australia, I can literally force the water to drain anti-clockwise, but it always, *always*, slows, stops and reverses direction to its natural clockwise direction.
What's your latitude? Are you sure there is no asymmetry in your sink? It's my experience, that with a symmetrical basin, with no influence, it will do what you said. I've never seen a case, where once a direction is established, it doesn't continue to swirl in the same direction.
I get the logic, I'm not five. It's just that they already have the science behind it proven, their experiment supported it and although it was only one, more ( while statistically better ) are also unnecessary. They already proved their point. I'm just saying they don't need to waste more of their time to prove something online to a single guy in a comment section.
@@mrcookedbacon324 Good science shows results through repetitive experiment. One instance only demonstrates it works one time. Demonstrable repetition is not a waste of time.
I did this experiment myself as i travelled from the northern hemisphere to the southern, in Kenya. I used a buck, a tooth pick, a funnel and a bottle of water. It did exactly as your experiment did. We also did it on the equator and there was no movement from the toothpick. The water didn't swirl in either direction.
If the water swirls at all, it will be random. It will almost always still swirl, from some other influence. It doesn't take much at all, to start a vortex.
Flat Earthers right now ... What if it's a stationary Earth with local sun and it's the path of the local sun and moon influencing the water swirl? 🫢🤔 Your experiment started with an earth rotation assumption. Just saying. 🤷♂️
@Morthos “how bout you repeat the test hmm.” Really? Are you in grade school? First of all, you do not know for sure that they did it multiple times. Where are those facts? If they did, why didn’t they show the multiple results for confirmation? 🧐
Further to my previous comment, I need to advise the planet pole illustrations are not clear or satisfactory to convey actual "mechanism"... ask other engineers next time. (?)
Water swirls A/ in the northern hemisphere : Clockwise B/ in the southern hemisphere : Anticlockwise C/ at the equator it is static This rotation effect is due to the Earth's rotation towards East and the pull towards the Northern & Southern poles attraction. I may have not explained properly... but the secret behind is this principle.
So maybe we are misled by the obvious. The water is swirling the exact same direction in both hemispheres. Think of the swirling water relative to the solar system instead of where you are standing. If Jill is at the north pole looking straight down on the water, she is looking south. If Jack is doing the same at the south pole he is looking north. They are both seeing the water swirl the same way but they are looking at it from opposite ends of the planet.
Just to clear, hurricane that affects the northern hemisphere are form in the south. Satellite images show CCW swirl because the movement of hot air is from bottom to top. Therefore the images shows the other end. It is like placing the camera at the bottom of the pool instead of placing it on top.
This deserves a follow up video in which you position the pool so that the drain is either perfectly at the equator or at either pole so that the outer side of the pool is as close to either/the other pole as possible to see if the angular momentum cancels out or not.
Hmmm. Is the coriolis effect actually great enough to influence that size body of water? And is one experiment sufficient for that conclusion? Just the one? One with flexible-sided vessels which could conceivably result in water flowing down inclined-planes to create some sort of vorticity? On a substrate of...what gradient? With a drainage system whose bends and twists may or may not be capable of exerting a rotational influence? I think this needs to be rather more rigorous before it gets to make any claims.
It is the grooves and shape of the container that guide the direction of the water flow. It's why you can drain your duel kitchen sink and watch as both sides swirl in different directions. If you look at the pool in the video you can see it is not balanced in shape and that it has grooves at the bottom.
To be fair, if we hypothesize these rotation occur randomly, meaning no difference between water rotation between northern and southern hemisphere, the probability of having this result is 1/4. So to reject null hypothesis, we need to repeat the experiment to see if it demonstrate different result and statistical analyze data to see if it significantly differs. Anyway, I agree with the principle and how they eliminated confounding factors but this experiment has not just completed yet.
One of the most awesome projects I've ever had the opportunity to be a part of. Derek made it happen!
hi Destin, i'm indonesian. i tested right at equator, it just doesn't swirl at all, has no direction. why ;(
Gnouveli Post a video of it
SmarterEveryDay you both talked about how storms rotate based on their hemisphere. what would happen if this storm crossed over? or does this just not happen
Chris Bowe that's a good question and I'd actually like to know the answer, maybe one of these guys will make a video about it. It's so nice to see someone actually asking a question for the sake of curiosity in the UA-cam comments for once! Props!
SmarterEveryDay how will the water swirl on equator?
How does water swirl at the equator?
thats a really good question.
One way or the other based on even finer differences in water temperature, container geometry and initial conditions.
ArchaicMuse so in a perfect world is it possible for water to not swirl?
ahmad al khateeb in a perfect world the water would go down the drain and it would look like a cone of water. This is what I think would happen.
in perfect world,water would have laminar flow,no swirls at all.
still one of my all time favorite colabs!
Why is this comment three years old and only got four likes? Lol
Now, it's 184
Now 258
The structure of these videos so they work best when played simultaneously is actually awesome! I never watched either of them but watching this is just so cool how you take turns speaking and the video is set up so that there's always something to be looking at- it's just so immersive I feel like I don't have even a second of idle thoughts before something else happens but it's also not like it's an overwhelming onslaught of information. It's just so we'll made to keep the attention of the viewer
these two guys are really good for stage play script writers...
Agreed
At the time I hadn't noticed that Destin, living in an imperial country, used metric units and Derek, living in a metric country, used imperial units.
It's worth noting that both systems are commonly used in either countries. especially within the science and engineering fields.
+Black Fedora The two countries where the experiments were undertaken and therefore relevant to the experiment and Jimmy Greys comment - namely Australia and the U.S.A.
From what I've seen, the Anglophone countries tend to be somewhat mixed in their usage of imperial vs metric. In America, while using imperial mainly, most still know the metric system and it has some common occurrences, such as using liters often. People in the UK, while being mostly metric, have occasional thing that are referred in imperial.
The UK is a very mixed bag indeed. A person's height, weight, waist size, etc will always be quoted in feet, inches, stones or pounds (regarding weight, it is near universal to quote stones and pounds rather than just pounds) - conversely in medical practice all of these must be recorded metrically. Many people also know their weight in kilograms, but it's rare indeed for them to express it that way.
Groceries and indeed most consumer products will be expressed metrically, with the exception of beer which are almost exclusively sold as pints or half pints, milk is labelled both metrically and imperially, British people will however always refer to it imperially.
The situation is more complicated for motoring. Distances and speeds are still in miles and miles per hour respectively, most British people would also be able to refer to directional distance in yards or metres fairly accurately.Fuel is sold in litres, but fuel economy is miles per gallon. Engine size is in litres or cubic centimetres.
In my experience I think it's fair to say most British people 'think' in imperial terms though are quite happy using metric measurements or expressing them if required to do so.
Yeah, it's hard to deny that if the British didn't hate the French that much, we'd be universally using the metric system today. The British came around eventually but not before leaving themselves and the rest of the colonies in a dismal state regarding units.
Birds fly upside down in the southern hemisphere.
ua-cam.com/video/Xc4xYacTu-E/v-deo.html
That's right. And the crows fly backwards to keep the dust out of their eyes! I've seen them myself
Been there, done that :)
Don't be stupid. In the southern hemisphere, we don't have birds because they fall into space.
Pfft, you believe in birds?
the way how the guy on the left is so close to the toilet when it flushes makes me extremely uncomfortable
And then he wipes his lip
steph k the way you haven't noticed that I exist makes me extremely uncomfortable 😍😘
This needs to be top comment.
Love clean toilets
technically speaking, there is no such thing as clean toilets.
I served a mission for my church in Brazil. One of the first things I tried, was fill a sink with water, let it sit over night, then pulled the drain plug with a string, rather than reaching in. It indeed swirled clockwise. I tried it several times with a sink behind the house, that is normally used for washing cloths. It too drained clockwise. The toilets were no indicator, since the offset jets determined the direction of the vortex when flushed. I was in Minas Gerais, which is far enough south, to make it pretty reliable as long as the water had time to completely stagnate. I even placed a board over the outside sink, to make sure no wind could disturb the water. If you drained the sink immediately after use, any turbulence in the water would override the effect, and it would swirl in either direction, It didn't take much, to influence it.
It’s just not true.
@@0Logan05Did you try it for yourself?
It's interesting to note that at the level of a tornado, which is considerably bigger than a bathtub but still pretty small on the scale of the Earth, about 95-98% are said to rotate cyclonically (counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere), but there is that small fraction of anti-cyclonic tornadoes.
Yes, I've heard of these "reverse" storms, but I never saw a percentage given. At a hurricane level, there has never been a "backwards" example in all of human history.
@@kdwaynec Cyclones (hurricanes in the southern hemisphere) rotate clockwise. All the science websites say its due to Coriolis effect. This experiment wasn't needed.
If all tropical cyclones/hurricanes rotate counterclockwise in northern hemisphere and all cyclones spin clockwise in southern hemisphere, i don't see why there'd be any doubt.
@@burtan2000 0) Because it is an incredibly small effect for a pool that is 6 feet across.
The physicist who originally did the experiment was somewhat surprised that it worked.
Why do it?
1) Because it is cool to do.
2) Because replicating results is what science is about.
Hey can I copy your homework?
Sure, just change it a little so no one notices.
Just go to the other hemisphere and there, you have original results.
1:50 why did the American say meter and the Australian say feet 😂😂😂
Jack 64 I’m pretty sure they are both American. The way Veritasium said Australia sounds very similar to how I hear a lot of Americans say it and he also said near the beginning “in the other hemisphere” and “when I was in Sydney Australia” which would be the sort of thing someone from the northern hemisphere would say
@@mission101 veritasium is Canadian and he moved to Australia
Edit:to clarify, he was born in Australia but lived here for a very short time before moving to Canada with his family until he was old enough to move out when he finally came back to Australia.
@@kierstanfaulks then why does he say australia wrong like every other non australian says it
@@elladay7913 What is the right way to say it?
@@KristinNirvana youre meant to say- oh-stray-lia people from the US say oooh-straai-lia
Once again, we've learned something, thanks to the Simpsons.
but the Simpsons was wrong, Lisa tells Bart the toilet and sink are due to the effect but like this video says the effect is overcome by the design of the toilet/sink
Physics class. Remember?
@@V_2077 but later on they show that it's because of the design
Southern hemisphere : we do clockwise motion
Northern hemisphere : we do anti-clockwise motion
Equator : I miss the part where that's my problem
On the equator you don't get water. Except for all of the oceans, lakes and really everything.
@@cones914 Underrated comment xD
*Sad Equator Noise*
In other videos, result is opposite
😂😂😂
legend has it flat earthers can make up a reason for this
There is a screen inside your phone that manipulates and shows you fake stuff.
they are paid actors, and they have installed pipes to pump water in to make it spin
No it is based on how the basin, or in this case how his pool was setup. The shape will determine which direction the water flows. Nothing to do with where it was located. People are fooled so easily!
@@skyisthelimitreadyornotfor2 Sigh, repeat the experiment yourself. Do it a 100 times, re-building the setup equipment each time so that you eliminate that "how the pool was setup" effect. Take a look at the results. I bet 99% of the time you'll get the same result.
@@zirkoni42 r/wooosh
And with that, the flat earth 'theory' goes down the drain :) .
Nuh uh, just because the earth is flat doesn't mean it doesn't spin! :P
Nah, it's banana shaped, and dipped in herbs and spices for best taste ;) .
Let's wash our hands of these puns
We wouldn't want this thread to spin out of control
devzer0 i think its pretty washed up now
You might get more consistent results with a very long pendulum (Foucalt's pendulum), but that would be more expensive to constructs. There is one in my city and it is built into a tower so it is shielded from weather. The pendulum swing is steadily altered by the Coriolis force, which can be observed by a pattern drawn by a stream of sand coming from the pendulum weigh.
More important that is not the question. The question is about liquids. This remembers me when students do all the calculations properly on a math exam and then forget that the question was about the diameter and not the radius of the circle
False. If you see a crane when it's not working the ball on the end of the line does not move and its way bigger than a display in your city.
@@crownnothin, wrong case. Pendulum swing precession applies to those already swinging. Coriolis effect won't affect still object.
@@crownnothin - "False. If you see a crane when it's not working the ball on the end of the line does not move and its way bigger than a display in your city."
Cranes that aren't working don't leave an unburdened line all the way down, lol - they keep it hoisted to the top so it doesn't like, break things, or itself, when not in use.
The other problem is as they mentioned above, if you hang a line outside it'll have things like wind pushing it around. An openly swinging crane line isn't going to show the Coriolis effect because it'll be swinging in the wind (hence, they don't leave them hanging when not in use), which is why the Focault's pendulums are built in towers so they can be shielded form the weather.
@@KingBobXVI > which is why the Focault's pendulums are built in towers so they can be shielded form the weather.
Yah, my high school had one in the atrium of the "science silo" -- a round wing that contained most of the science lab classrooms. (There was a fad of building science classrooms like this in the 1950s and '60s.)
the world need more videos like this...scientists in the bath and on the toilet.
Lives in us: 1.5 M
Lives in Austalia: 5 foot
lul
You do know that "lul" means "dick" in dutch? ;)
Lul lul lul lul lul lul
LUL
Werewolf's Channel so I should never, ever, under any circumstance, write 'lulling my ass off'??? ...good to know. I'll never be *that* stupid!
Werewolf's Channel lul
Don't know how I didn't see this 4 years ago, but thanks UA-cam recommend, you were actually helpful for once
I once cut the base off a 5 gallon drum, wrapped copper wire around the neck and hooked it to a car battery. When I switched it to positive it increased the up the spin rotation and when I hooked it up to negative it just went straight down. I don’t remember how well I controlled the experiment to not have any motion in the water prior to pulling the plug. However, the effect that the positive and negative electric current had was repeatable.
I don't dispute the explanation of the coriolis effect, but I have to question whether the speed difference over a couple meters is significant. (Distance from pole to equator 10M km, speed at equator 460 m/s, therefore each meter represents an average change in speed of .00005 m/s per meter.) This experiment could easily just be a fluke. Before jumping with joy, I think multiple better controlled tests would be needed.
this is why they said that the effect is so minor that in general, it gets lost in other factors that influence the way the water drains. the moment you throw in any disturbance to the water before the water starts to drain will alter how it drains WAY more than the rotation of the earth.
+Ursinos I am aware of that. I have discussed this in another thread, and there I even stated : "The paradox of my criticism is that if everything were perfect I would expect the result that they got. I just don't believe that they proved it." And there's the rub. The effect is so small that I'm not convinced that this experiment can eliminate other factors that influence the way the water reacts. Even convection currents due to where the sun is shining could be a larger effect.
But my position may be weakening. In that other thread someone posted this reddit thread : www.reddit.com/r/IAmA/comments/38gekk/iama_guy_who_makes_science_videos_on_youtube/cruudik
They repeated it 3 times time though, and still same results. So this happened: 1) the results line up with their location 2) same results 3 times. What's the chance to have it by accident? Should have tried with different pool setups/at different times (day/night) though to be 100% sure.
KonstantinGeist Need more data!
CONSTRUCT ADDITION PYLONS
Have your done the experiment a hundred times, and then swap pools, and then a hundred times again?
Yan G yeap, that would be the very minimum to ensure there are no other effects at play (or even slight variation of the pool shape). Even then I'd bet the results would be close to 50-50. After all it's a chaotic system and the scale is *far* too small for the Coriolis effect to actually matter (at larger scales we already know it does).
Oh, and waiting for 24 hours for any initial rotation to settle is ridiculous. I have no problems with the video other than it implies this is proper methodology.
clear science right before your eyes and still arguing a moot point...read the description please!
phil tripe, I have higher standards for what constitutes "science".
@@jasondoe2596 no one needs your science.earth is spinning for a fact.so if you do this perfectly you will get the same result for 1000 times
Yan G
They did do the experiment multiple times 😀
This is fake. The water would of flown onto the sky in australia.
Electrified Heart lol
Nathan Weatherly that’s not a woosh.........
@@nw3473 he just don't know the reference
Words fail me on this.
He had us in the first half
As a physicist, I'm still dubious about these results. Of course the Coriolis effect is real, but let's do a little math to quantify how much impact it should have in this experiment: Huntsville, AL is at a latitude of about 34.7°, so that means that an east-west circle around the globe at that latitude has a circumference of around 40075*cos(34.7) km, or around 32947km. If we assume that kiddie pool has a radius of about 1m, that means that the northernmost point in the pool is about a 40 millionth of the way around the globe from the center, or about 0.000009 degrees. We can calculate the difference in distance around the globe at that slightly different latitude: 2*pi*(6371*cos(34.7 deg)-6371*cos(34.7000009 deg)), which says that the water at the far north edge of the pool will travel about 350um less than the water in the center (and the water at the south end will travel that much further). So if it takes the pool, say, one hour to drain, that's a total difference of about 15um of travel between the water in the center of the pool and that at the outer edges. 15um! That's 1/5 the diameter of a human hair. And that's over the course of an hour. I really doubt that's enough of an effect to set the drainage direction in motion.
This was an interesting experiment, but I'd really like to see it repeated 50 or 100 times, perhaps with even longer times between fill and drain. I'd guess the 'success' rate would be in the 80-90% range, perhaps more.
I think the geometry of the drain can also create vorticity, as in case of the wings of an airplane, the no-slip boundary condition on the surface of the wings is a source of vorticity even in previously irrotational velocity fields (see for example the Kutta condition). What I mean is if you have a drain formed as a Kaplan turbine for instance, even if the turbine is standing, the flow will begin to rotate automatically and that is not becouse of the Coriolis force.
This seems too small of a distance do you have any Coriolis effect visible
Ding ding ding!!!! We have the winner!
I just watched this and the first thing that popped into my head was any irregularities in the drain, the bottom of the pool that water is flowing over, or even the direction the ball valve opens could start the motion in one direction.
Further exemplified that the rotation happens at the drain itself. Simple scale analysis shows that Coriolis would not be affecting the water at this distance.
@@grillmaster95 You would only see the Coriolis effect at/near the drain as the reduction in radius is needed to markedly increase the otherwise very small difference in angular velocity of the water going around the outer edge. Coriolis effect on this scale is tiny, but when you have a radius reduction on the order of 50:1, the magnifying effect it can have on angular velocity is rather extreme.
What if a tornado travels from the northern hemisphere to the southern hemisphere? Does it collapse?
It's impossible as the coriolis force dictates that the path of hurricane would move towards the poles away from the equator
Interesting...
I don't think that happens, we always see tornadoes or hurricanes making landfall in coastal areas away from the equator.
Actually making this happen would be a problem as the larger scale rotation of the wind would be pushing the tornado away from the equator. But lets just assume for a moment you could then no the tornado still wont collapse it's not the vortex rotation that's driving it it's the atmospheric inversion (The fact that warm air high pressure air is trapped bellow cold low pressure air). So long as the inversion remains the tornado would keep going though it's vortex should begin to slow and even eventually stop and start going the other direction if it lasts long enough which is pretty unlikely it has some pretty significant momentum and they just don't last that long.
Brian actually, tornados are too small to predict their rotational direction. On this small a scale you need really calm initial conditions to see an effect of coriolis (like they are in this video - they let it sit for quite some time and then don't even dare to simply pull the plug) you don't have such conditions in the free atmosphere.
It's different with the much bigger hurricanes. They rotate ALWAYS in the direction dictated by coriolis and can't exist near the equator (between ~5 degrees north and south) due to the lack of coriolis force. So yes, a hurricane would break down but no, a tornado wouldn't.
This idea is so weird to me, because every toilet I've used doesn't swirl in any particular reason. The water just kinda goes everywhere.
It is because it is the size of the pool that makes it. A toilet is simply to small. You need at least large lakes to get it big enough.
I agree with Eleanor. I think Veritasium headlined toilets mainly cos it's kinda smutty, even though the vid itself is excellent in my opinion. I agree with Filip that size is important. Not just the size of the body of water but also that of the drain hole, take a look at Google images of reservoir drain holes, where the surrounding water doesn't appear to swirl as it goes straight down the sides. I suggest elsewhere it's the interference caused by a narrow hole that results in swirl in one direction or another.
I have physically experimented with it. A pool a few meters across could be made to swirl in different direction by manipulating it a bit. But if in sizes of several kilometers across, the earths rotation would most surely be the dominant factor.
The experimenters in the vid took a lot of trouble not to manipulate the water themselves, by leaving it to settle overnight, and draining it with valves located outside the pools. But I guess you're saying the pools themselves are still far too small to convincingly show up the earth's rotation effect. What do you think of my point about drain hole size as a factor in swirl, leaving aside the question of direction for the moment?
I don't know but I believe the drain hole is an important key to the rotation in small pools. But someone should run the numbers on this, cause I really wanna know.
Coriolis effect does exist but only noticeable in larger scales such as wind patterns. In the case of this experiment, there were still many factors such as the sizes of the drain, valve direction, small creases on the bottom of the kiddy pool that may diver the water heading towards the drain in one direction in a molecular level. Furthermore, a proper experiment would've included multiple attempts in similar conditions. One guy did it outdoors, the other did it indoors, and each person used only 1 pool and only did it once.
True, an experiment is an experiment if it is repeatable and the answer is decided based on data that is consistent throughout the runs
It is about size. The bigger the pool, the bigger the Corriolis effect. If the pool gets to slow, other factors like micro currents, friction, air draft, the shape of the container etc will determine the rotational direction.
I literally posted both of the old videos yesterday, when someone posted to fb a video where people walked across the equator and supposedly proved the coriolis effect, but they were pouring the water in the complementing directions. People were saying, "Mind Blown!" and other ridiculous exclamations, and I just sat there wondering how I could tactfully tell them it was a trick. Thank you for combining the videos!
Viola James good :) Yes, so often people miss the key factors. Could include myself as well, in some topics I don't understand so well. I'm also happy this video was released. I had been wondering if it is true or not. This confirms it pretty well. I mean, to me it looks valid. It may not be scientific as a test (two) arrangement, but it is at least a good effort and well explained.
The effect would be even less near the equator because the ratio of distances to the axis is closer to one.
Still awesome!
Hello!
Wow hi
😍😍
The King of Random Sharap
Wow I didn't know you watched these videos
LiacosEM demonstrated this can work with just a cylindrical container with a hole in the center provided you let the water settle first and remove the drain plug from below. The cylinder was only about 10 cm diameter.
Fantastic demonstration. Thank you for the effort you both put in to make this video available.
“Wish me luck Destin”
“Good luck Derek”
That was so perfectly done lol
This video and experiment are great! But, as with most scientifically focused videos, too many of the comments leave me questioning the future of humanity.
You guys have the BEST video on this question. I "seemed" to observe that the water drains from my Canadian tub in one direction one day and another another day, so I needed the science.
Great, and thank you! Every physicist knows this, but there are so many counter experiments with additional forces involved. It's the Coriolis effect, or Fouceaults pendulum if you like.
Wonderful video, and clear victory for physics. Added it to my favorites and physics lists.
What Direction does water drain from the equator?
Down.
dayshiryu it depends how many milimeters you are more un nort or the south
Hm, ideally it wouldn't turn at all. Just moving straight from the outside to the inside.
i think there would be no swirl at all based on what he said, and the water just flow directly into the hole
If you go back to their example with the pool at the poles, you should be able to figure out what would happen if the pool was moved further and further from the equator. When the pool is at the equator, the water on either side of the drain would be moving at exactly the same speed as the drain, so as the water moves closer to the drain it wouldn't go ahead or behind, thus no rotation. The pool would just drain straight.
You guys are better advertisers/marketers than anything else.
cool, but I hope they ran the test at least 5 times to make sure it wasn't just coincidence. (I'm not totally sure the pool was big enough)
My thoughts ! in science a proof is something reproductible, so ...
That would be a bit of a waste of water, but I expected it to be done at least twice
@@fruz1378 Read the description. They did repeat 3 to 4 times.
@@omarahmad3878 good catch, it does not show up until one clocks on th "show more" button.
With Coriolis is not a matter of length alone. Velocity is inportant too. I was surprised as well by the small dimensions of the pool but the water is flowing very slowly. I'd like to know the Rossby number which will give you the importance of Coriolis forces over inertial ones...
I can imagine the neighbours looking out their windows to find a grown man screaming out science stuff beside a colourful kiddie pool.
Very good video, well done guys! I’m just wondering why you didn’t add the dye before opening the drain, maybe wait the same time you deemed the water had no spin then add the dye, wait a few hours to ensure no motion and then open the drain?
But the video is great! I really enjoyed watching and I feel richer now 😊👍
If you add the dye before opening the drain, it dissipates and you can't see it, and/or you introduce motion to the water before the effect can start.
Adding it after it starts, allows the water to build its own momentum first. A few drops of dye isn't going to change the direction of kilograms of water that's already moving.
I’ve actually seen this effect demonstrated by the equator in Ecuador. Same basin on legs with drain into a bucket underneath. They added flower pedals to see the motion. They did it about 20ft north of the equator and then picked up the basin and repeated the same experiment 20ft south of the equator. They effect is still apparent even that close to the equator.
Are you sure they weren't cheating somehow? I think the effect is effectively zero near the equator, as all parts of the pool are at very nearly the same distance from the earth's axis.
@@andersmusikka one might think. I know I would. I saw it with my own eyes. They used the same basin so the same constants on both sides. It was more of an educational demo as opposed to a magic trick.
Cue the flat earthers!
nah, make sense on a flat model as well. The rotaition could be the Sun, travelling over the equator. Everything on the left would gain a small pull on their right side. Just like a passing ship, causing turbulence on each side, with opposite water-spin-direction. The effect might be proven, but is the spin too? Maybe we can try it with technology of our century... just wondering.
Sortaray flat Earthers surely can't believe in the mass to gravity correlation, right? Because what the hell is under the flat earth? Infinite mass?? 😂
how could i forget the anwser to this question... and why do you want to know in the first place?! Im not a believe-expert like u, i guess.
Sortaray are you talking to me? I want to know because my brain functions on logic.
we tried doing things with modern technology. but flat earthers are convinced those are conspiracies or everything we get from them is fake
This level of commitment is the definition of loving science
Too cool! Coririolis rock! The Earth rocks! You guys rock! Well done. I FINALLY got hub to understand this principle (I’m a MSc in applied mechanics/combustion engine engineer/ and he is an archeologist). A million THANKS 🙏 to both of! This version (showing both besides each other) was very pedagogical.
I do remember as a kid deliberately reversing the direction in the tub drain, and it would always reset itself
If you try to flush water inbetween the hemispheres it starts floating and attacking people
That's a very interesting video and one that has left a few questions in my mind. If the water were to emerge INTO the pool from the hole in the bottom, do you think it would begin to turn counterclockwise in one hemisphere and clockwise in the other? I'm asking because weather events are made up of either an ascending air mass or subsiding air mass. When the air mass is subsiding it moves along the surface towards the lower pressure area away from the center. When the air mass is ascending it moves along the surface towards the low pressure in the center. Therefore I'm wondering if the water were to move away from the center of the pool would it rotate the other way?
Probably not. Two problems. First, Your in-flowing water would start out so turbulent that it would completely overwhelm any Coriolis effect - it obviously hasn't been sitting still for any time at all.
Second, pumping water in from the center you'd get an angular momentum DAMPING effect as the radius of the pool increased, as opposed to the angular momentum exaggerating effect that you get when you reduce a radius.
The Coriolis effect is already incredibly minute at these scales, so you need the reduction in radius in your experiment to make it visible at all - going the other way would make it impossible to detect.
@@Jesse_359 Hi Jesse. Thanks for your reply.
So the swirl of water would be the most intense at the poles/rotational axis of the earth?
Yes, that is right. It's why a Foucault pendulum rotates the most at the poles, and not at all at the equator.
seasong There would be 100% speed difference as it would be going the same speed in the opposite direction
Edit: angular velocity or whatever, not technically speed
it seems that, we're asking the same question yet conclude a different hypothesis
This effect is caused by the difference in linear velocity around the axis between two positions with the same angular velocity.
That difference is caused by them being at different radii from the axis.
Distance from axis on the surface of a rotating sphere is proportional to the sine of the angle from the pole.
The greatest difference in linear velocity will occur where the greatest difference in the sine of the angle is.
The angular size of the pool being constant, this will be where the gradient of the sine graph, dsin(x)/dx, is at its greatest.
dsin(x)/dx = cos(x).
cos(x) is at a maximum where x = 0.
This effect will be strongest at the poles.
Further, cos(90°) = 0, so at the equator there'll be no effect at all.
I can't name a better duo for science videos. Also, 5 minute video = good. Just need something over lunch and the length here is perfect.
It's more fun to find Coriolis effect in long range precision shooting
I appreciate the effort you have gone to to undertake this experiment, however, for this to be scientific, it must be repeatable. One single result doesn't prove the existence of the Coriolis effect on this scale. It could have simply been a coincidence. There are factors which could affect the direction of drain rotation more than the Coriolis effect in day-to-day life. It's like the butterfly effect, tiny influences in the initial conditions can change the results dramatically. The wind direction, convection caused by sunlight etc. Possible improvements: Covering the pools with perspex and a cut a hole in the top to let the air in. Put the pool under a gazebo to shade from all sources of light. I would be interested to see a follow-up video of the experiment repeated several times.
read the description "For the record Destin and I repeated the experiment 3-4 times each in each hemisphere and got the same results every time."
It would be interesting to include a discussion of the great air masses (and some currents) flow in the North Atlantic (clockwise) and South Atlantic (counterclockwise), the opposite of what is shown here.
A long time agi I worked in a laboratory that studied airflow in buildings. We had a symmetrical air room there where we could measure air speed through the entire room which was blown evenly from one side in that room. We noticed this effect as well. We had not enough data to prove anything, but interesting it was.
Hurricane - north
Cyclone - south
Typhoon - equator
No, it's this :
Hurricane - atlantic ocean
Cyclone - indian and south pacific oceans
Typhoon - north pacific ocean
@@candyneige6609 in the USA and some parts of the northern hemisphere the storm is called Hurricane and in the middle which is the Equator its called a Typhoon in the southern hemisphere however its called cyclone like in Australia
@@candyneige6609
Hurricane - Atlantic and northeast Pacific ocean
Typhoon - northwest Pacific ocean
Cyclone - Indian and south pacific ocean
Hotel - Trivago
@@gissanchi7020 You won this comment section
Fun fact : Due to the coriolis effect, the hair on men's is swirled in different direction. You can look at their occiput and see the direction will vary depending on which hemisfere you are or on which hemisphere they've been living
Wondering if, when you repeated this experiment, you completely rebuilt and re-leveled the base of your pools or even used completely different ones each time. As from what I understand of the coriolis effect, your pools are far too small and would drain far too quickly to be significantly affected by it. I think what you got was fairly lucky and not a repeatable result. Would love to see someone actually do the math on it.
It depends on how the water begins circulating into the plug when you pull it. You can make the swirl go the other way. Some outlets are not so symmetrical. This will cause the water to drain in one direction most, if not all the time. When drains are manufactured, they may all drain the same way.
veritasium, I have a question that none of my teachers have been able to answer.
We know that photons are the particles responsible for the electromagnetic interactions and that they have no mass.
So what is it exactly that we feel when we hold two magnets with the same pole near to each other? What's exactly happening between these magnets?
I would love it if you made a video about it!
-thank you
I believe the answer lies in exchange in momentum due to exchange in virtual particles, try to find out more about virtual particles, I don't remember much myself so I can't give you a detailed information.
You learned a more valuable lesson than why the magnets feel force. You learned that teachers don't know much, which is why they became teachers, and not something better.
I suggest that you watch this video:
ua-cam.com/video/jq8WOUFeCcg/v-deo.html
This is a really tricky concept that takes a lot of knowledge of advanced physics to understand. As a college sophomore I know just enough to see how complicated it is. A gross oversimplification is that it is due to relativity and quantum mechanics.
The Coriolis effect is in my top 20 favorite effects.
What are the other 19?
(I would like to read about them)
@@anujgupta6347 same
what about our spiral galaxy
The rotation, in which the galaxy (if it's a spiral galaxy) swirls is completely random, or it can be influenced from the existence of dark matter, which is confirmed to surround every galaxy, including our own Milky way, or the rotation, in which the central supermassive black hole spins.
Rotating galaxies take shape of a spiral, because the closer are the objects (stars, nebulae) to the galactic center, the faster their rotation is around it. So the whole body of the galaxy starts to bend into a spiral.
However, then it gets weird here. The dark matter, which is surrounding our galaxy - it firmly holds it all together. The stars which are orbiting the galaxy center further than others are orbiting it faster. The rotation curve, which should be decreasing with the distance from the galactiv center actually stays constant throughout the entire radius of our galaxy. Dark Matter, whatever it is, is weird.
Pretty sure it has to do with the rotation of the central Supermassive Blackhole. If I'm remembering right.
Ferarn McÆternitum oh ya
I gave it a blow during the beginning of its formation, randomly. So it is how it is today. you're welcome.
Fact check yourself on the bending in to a spiral. The winding problem says you are wrong.
They forgot to mention that there is a pocket of air that forms underneath the drain hole, on the inside, where it cannot be easily seen, that pocket of air causes the water to have to push past it because the water cannot push the pocket of air down, it can only flow around it. The pocket of air is what causes the water to drain out so slowly. If you take a simple drinking straw and push it down towards that pocket of air, all of the water will, at some point, rush out of the sink very very fast! The reason is simple: because that pocket of air can suddenly pull air from outside of the water swirling down into the drain! It makes an enormous and very loud sucking noise, that pocket of air is why fluids drain so slowly through even a large sink or basin. The water can rush out of a steel sink fast enough to cause a slight contraction in the bottom of a steel sink, which can be heard as it rushes out. I've done this myself, that's how I know it works! :D
Wouldn't the Coriolis effect be negligible on such a tiny body of water? I'm no math wiz, but I imagine the differences in velocity between the sides of the pools nearest to/furthest from the poles would be so tiny as to be nigh incalculable. Seems like a factor as small as the pools' designs and how level they're sitting would do a lot more to influence the outcome than the Coriolis effect. We'd need to see this experiment done numerous more times with less imperfect conditions in order to confirm this definitively.
TheThrashyOne but you can see how slow the water moves initially. It only gains momentum as it drains.
Just worked out above: linear velocity differences of 0.1219 mm/s and 0.1246 mm/s.
"The Coriolis Effect is real." Yes, we already knew it was real. Cannon-balls and all.
u clearly havent met r'tarded flat earthers they believe nothing
them : we did it, we've eliminated all variable.
Dye and Wind : cough cough, am i a joke to you ?
Dye is not a variable in rotation. Wind, possibly. Depends on if it was windy. But these are pretty smart guys. I'm sure they took wind speed into consideration
Water always flows towards less pressure.
If the hole in a sink or a bathtub is just a little off center, or the tub is tilted just a tiny bit, or many other factors in production and installation, then the water will change direction.
This is easy to prove in the shower or the bathtub.
Just put a foot besides the drain, then the water goes one way. Then move the foot to the other side, and the water change direction.
This experiment is ok because it is a large surface, and the water is very calm, but in a toilet you can not decide this because the water is turbulent and coming from above with gravitational force, and the design of the toilet is random.
Hey, let's be somewhat sceptical about this, you have done this only once on each hemisphere, so there's still 25% chance that the effect is completely random xD
Yep. It should be done at least 5 times each. Not that I'm doubting the result, it does make sense, but any scientific experiment should be repeated to ensure that the result is not just random.
It should be done hundreds of times. On the 67th attempt the water swirls the opposite direction then it is falsified. This video proves nothing.
The effect is real and is called the "Coriolis Effect" after Gaspard-Gustave de Coriolis (1792 - 1843). The magnitude of the effect increases the further north or south of the equator one goes.
wouldn't putting the dye in, have affected the experiment though?
狂猫
U mad cat
A scientist, and an engineer, both describing the same thing differently with different words. It is a beautiful thing.
Education is what lets you get that. Learn the words people, so you don't become internet stupid.
1:04 I'm freaking out about how casual he is being so close to a toilet and touching it.
Do you sit on the toilet or do you stand? In developed countries the toilet is mostly the cleanest place in the house due to constant desinf. And the water is dringing water mostly.
@@Ras548 "dringing" water? eeewwww
Little known fact: If you drain a tub EXACTLY on the equator, down to the millimeter, the water won't swirl as it exits the receptacle.
It will rush-out like a circular waterfall.
Though, in this case, when I say fact, I mean totally lying.
The drain is what matters, if you have 2 drains connected, which ever way the drain goes (to the right, it will swirl clockwise) and vise versa.
umm... what?... that doesn't make sense... the direction of the drain is relative to which side of it you are on... so this is a joke?
JGirDesu he had 2 sinks on each side, each one went a different way, yet the drain went down the middle then in between them, connecting them.
| |
-----
|
|
I think both sides of this dispute are null. The first hypothesis is that the direction in which the water swirls is either clockwise or counterclockwise, depending on which hemisphere, due to the angular momentum of the earth and the Coriolis Effect when no outside variables are present. The second hypothesis is that the effect does not affect the system enough over such a short period to overcome outside variables and thus does not reverse the clockwise or counterclockwise flow of the water. The argument is "If I eliminate the variables that cause the effect to be false, it is then true."
That's great, BUT
...at my place in Australia, I can literally force the water to drain anti-clockwise, but it always, *always*, slows, stops and reverses direction to its natural clockwise direction.
What's your latitude? Are you sure there is no asymmetry in your sink? It's my experience, that with a symmetrical basin, with no influence, it will do what you said. I've never seen a case, where once a direction is established, it doesn't continue to swirl in the same direction.
Do it a thousand times, not just once.
Pretty basic demonstration. Not much need to go to those lengths.
@@mrcookedbacon324 I flip a coin. It comes up heads. Therefore, it always comes up heads.
I get the logic, I'm not five. It's just that they already have the science behind it proven, their experiment supported it and although it was only one, more ( while statistically better ) are also unnecessary. They already proved their point. I'm just saying they don't need to waste more of their time to prove something online to a single guy in a comment section.
@@mrcookedbacon324 Good science shows results through repetitive experiment. One instance only demonstrates it works one time. Demonstrable repetition is not a waste of time.
@@raedwulf61 go try this exact experiment yourself dummy. i better afer the 10th time you will give up and realise just how stupid you really are
Long story short, you could've just looked at hurricanes from both hemispheres to see the if there was a difference👍👍
Uhm no, because atmosphere is an incredibly complex and chaotic system with a million variables. You can’t make such generalizations from that.
I did this experiment myself as i travelled from the northern hemisphere to the southern, in Kenya. I used a buck, a tooth pick, a funnel and a bottle of water. It did exactly as your experiment did. We also did it on the equator and there was no movement from the toothpick. The water didn't swirl in either direction.
I would expect that being so close to the equator.
What if you're exactly on the equator
The water will go straight down the plughole from all sides.
The water hovers in the air and then explodes
If the water swirls at all, it will be random. It will almost always still swirl, from some other influence. It doesn't take much at all, to start a vortex.
LIked the way they have presented it without unecessary B.S.
But did you consider angle of attack, perspective, and relative density disequilibrium?
Didn't think so.
Finally!!! I understood why hurricanes/ciclons spin the way they do. Thanks!!
Flat earthers right now: 🤯
Flat Earthers right now ... What if it's a stationary Earth with local sun and it's the path of the local sun and moon influencing the water swirl? 🫢🤔 Your experiment started with an earth rotation assumption. Just saying. 🤷♂️
Are the videos of the pools your only attempts? I would not state that a myth is confirmed with only one attempt on each emysphere
Mr Burton read the description :)
Oh I missed it. They should state it in the video XD
1 time test and it’s “Confirmed” 🤔 Edit: At least setup 3-4 pools and pull the valve on all pools at once.
they did this more than one time buddy
how bout you repeat the test hmm.
@Morthos “how bout you repeat the test hmm.” Really? Are you in grade school? First of all, you do not know for sure that they did it multiple times. Where are those facts? If they did, why didn’t they show the multiple results for confirmation? 🧐
Interesting that Destin, the American, said “1.5 meter pool”
and Derek, the Canadian/Australian/American said “5 foot pool”
Further to my previous comment, I need to advise the planet pole illustrations are not clear or satisfactory to convey actual "mechanism"... ask other engineers next time. (?)
My dairy queen ice creem swirled the same way in US and australia though.
www.popularmechanics.com/science/a15852/does-water-drain-backwards-southern-hemisphere/
Water swirls
A/ in the northern hemisphere : Clockwise
B/ in the southern hemisphere : Anticlockwise
C/ at the equator it is static
This rotation effect is due to the Earth's rotation towards East and the pull towards the Northern & Southern poles attraction.
I may have not explained properly... but the secret behind is this principle.
At the equator, all entering paths would slightly curve west, with a greater turn the farther north or south the start of the curve is.
Australian says 5ft, American says 1.5 m
ummm
So maybe we are misled by the obvious. The water is swirling the exact same direction in both hemispheres. Think of the swirling water relative to the solar system instead of where you are standing. If Jill is at the north pole looking straight down on the water, she is looking south. If Jack is doing the same at the south pole he is looking north. They are both seeing the water swirl the same way but they are looking at it from opposite ends of the planet.
Just to clear, hurricane that affects the northern hemisphere are form in the south. Satellite images show CCW swirl because the movement of hot air is from bottom to top. Therefore the images shows the other end. It is like placing the camera at the bottom of the pool instead of placing it on top.
One of the best videos of this channel.
Both these channels are true assets of the internet! Keep going brothers!
This deserves a follow up video in which you position the pool so that the drain is either perfectly at the equator or at either pole so that the outer side of the pool is as close to either/the other pole as possible to see if the angular momentum cancels out or not.
Hmmm. Is the coriolis effect actually great enough to influence that size body of water? And is one experiment sufficient for that conclusion? Just the one? One with flexible-sided vessels which could conceivably result in water flowing down inclined-planes to create some sort of vorticity? On a substrate of...what gradient? With a drainage system whose bends and twists may or may not be capable of exerting a rotational influence?
I think this needs to be rather more rigorous before it gets to make any claims.
I mean, they did mention they ran it multiple times in the description......
It is the grooves and shape of the container that guide the direction of the water flow. It's why you can drain your duel kitchen sink and watch as both sides swirl in different directions. If you look at the pool in the video you can see it is not balanced in shape and that it has grooves at the bottom.
Great , was searching for the other video to show to a friend. This is even better to kickstart the conversation
To be fair, if we hypothesize these rotation occur randomly, meaning no difference between water rotation between northern and southern hemisphere, the probability of having this result is 1/4. So to reject null hypothesis, we need to repeat the experiment to see if it demonstrate different result and statistical analyze data to see if it significantly differs.
Anyway, I agree with the principle and how they eliminated confounding factors but this experiment has not just completed yet.
To be fair, he claims they did the experiment 3 or 4 times in the description.