Well... The water being pushed back was interesting, although the real reason was not explained. The liquid compressed the air that was inside the hose. So far, so correct. But the the liquid starts to flow down the edge of the hose while the air moves up slowly. At some point the water above the hose was not enough to keep the compression on the air. Others were a little amateurish, too. Like a hose plopping off a barb in a demonstration of how strong pressure is... duh!
Another way to think about pressure depending on only the height of the water is to go to the edge of a lake, dig a small hole, make a channel connecting the two that's only a few centimeters deep, and then try damming that channel with your hand. The force of the water you're trying to hold back will feel negligible, even though there's a massive amount of water on the lake's side.
A really GOOD demonstration of a physical law/property. You can learn Pascal's law a hundred times, and even pass exams using it and its mathematical equations - but this short explanation followed by a pin-point "query to Mother Nature" with such a thin - even flexible tube, and so little extra water - will really do the job. People who watched this video will have the fact and physical law "nailed down" in their heads, part of their future intuition. I admit to have been surprised, despite my BSc. in physics (ok, from 40 years ago...) my Intuition had it that the AMOUNT of water (hence its weight) had to do with the hydrostatic pressure. I really needed that reminder of Pascal's law and its meaning. I learned something here. Thank you.
When you search the world for something that someone should have done long ago (and documented), but you find nothing... then you know you have got a gem. Cool video. I admire your perseverance.
Great demo! Honestly though, I think my favorite part was the bit about the technical challenges of this experiment - thank you so much for including that.
wait all the pressure on the dam wall comes from the height alone? a narrow strip of water has the same pressure ?? what about the weight of all the water behind it, what holds that back?
That is so cool... I knew the physics of it, and understood that it should work, but it is still REALLY fascinating to see that thin tube of water breaking that big glass, purely because of the height of the water "column".
I also understood that it should work but I wasn't sure how to actually do it. I wasn't sure there was plastic tubing that was strong enough (there is, I found some nylon tubing rated at 800 psi) or how to prevent bubbles from blocking the flow. I had various complicated ideas but adding soap wasn't one of them. Well done to whoever thought of that. One of my ideas was to suck the air out of the tube. Obviously more complicated than soap but I think that might have worked also.
@@davefoc Yeah, it seems like she did indeed end up at on of the simpler solutions for it. No matter which alternate solution I have thought of, they all end up being more complicated than the one she chose.
Nice demonstration of hydrostatic pressure. P= density x gravitational force x height I teach Physics to Anesthesiology students. That Hoover dam explanation was epic. I never realized that aspect. I learned something new today.
I'm really glad you had the foresight to dye the water in the tube. Notice that as soon as the vessel fails, it starts to fall, and the top of the vessel accelerates downwards at the expected 1 g. However, blue water immediately sprays in even faster than a simple 1 g acceleration from gravity could allow. This shows that the water has forces acting on it other than simple gravity- in particular, the spring-like elastic deformation of the tubing, and to some degree, the water itself (even though water is carelessly described as "incompressible", it does actually compress a very small amount). Without these forces, the top of the vessel and the blue water would have accelerated at the same rate and we would not have seen the blue puff.
They don't mention it, but it's clear the person at the top of the tower is providing a good amount of pressure from the top of the tube with the syringe. They are pushing quite hard. This is technically "cheating" as it adds to the force of gravity in the tube. To really prove that it's "just" the height, you'd need to have an open tube. Bleeding the air from the bottom as you fill the tube would be a good idea too. Just add a small bleeder valve.
I don't think you have to go to those effects to explain your observation. When the carboy bursts, the internal pressure drops to zero while the water in the tube is still at 43PSI so it squirts into the falling water just as it would into an open bucket.
I did a similar experiment the other direction. I dove into the deep end with the long pole we used to vacuum the pool. I put my hand over the tube so it wouldn't fill with water, then once at the bottom, I put my mouth on the end of the pole thinking it would work like a long snorkel. It almost sucked my lungs inside-out. Lol
Glad you're alright, you basically made a barometer with that set up. Lower pressure atmosphere compared to the pressure created by the depth of the water
Thanks for going to all of the trouble to make this demonstration! It's great to actually see a lesson, and not just learn it and accept it's probably true.
Gostaria de ver a experiência invertida para uma descompressão abissal pois um tubo chegando às Fossas Marianas por exemplo deveria fazer jorrar água na superfície porque com o tubo não há a compressão lateral; caso positivo podemos projetar para esse fluxo uma usina elétrica;
Wow! This is a great demo. I had known that only the hight is the determining parameter, but I had not viscerally internalized that fact. Never realized that the water pressure of a hose would suffice to generate the pressure to destroy a vessel. Welldone! Excellent visualization. Thank you!
Why didn't the hydrostatic pressure burst the tube near the bottom. If it was able to break the glass, shouldn't it have been able to burst the plastic tubing?
Great question! The tube is actually much stronger than the glass - it is made out of a flexible polymer which is manufactured for strength and durability. We chose this strong tubing specifically so it would have a much higher pressure threshold than the glass, all part of the preliminary testing stages.
1 - The pressure is at its highest at the bottom of the barrel. 2 - To break an object you need to apply a force that overcomes the forces that bound the atoms 😂 So p=F/A that means F=p*A😂 So if you have the same pressure on two containers the one that has bigger surfaces would be subjected to a higher force 😂😂😂 So, that makes a smaller container capable of handling higher pressures than a larger one even if they are built from the same material and have the same thickness of the walls 😂 3 - Increasing thickness of the walls makes a container capable of handling higher pressure 😂 that one with thinner walls even if they would have the same volume and are built from the same material 😂 4 - Most wrongly believe that the pressure is the same in all directions 😂 Completely false 😂 This is a little harder to grasp... Presure is caused by the atomic forces trying to reach a state of equilibrium... In short there is a specific distance that atoms like to keep from each other 😂 If you squeeze them they push back 😂 with the same force in any direction trying to get the space they like. 🤣🤣🤣 That means the presure is higher on the walls that have a smaller area even inside the same container... Now all this makes that a container that has a big length compared with its section area will actually have less pressure on the long walls than on the short ones... In other words in pipes with smaller diameter the pressure would be smaller on the transversal walls than on the walls on the ends of it. That means a tube that allows fluid to flow through it can handle a higher pressure if it has a smaller diameter. And that's why the barrel breaks but not the hose. I bet the barrel would break even if the barrel and the hose would be built from the same material. 😂😂😂 Sorry for you... It's good to make since teaching fun, but too much circus distracts the attention from reality... Sorry for you all, but physics can't be truly learned before learning enough math... This world is just a big freak show 😂😂😂😂 Ps Consider how much pressure can handle a small aluminum beer can that has transversal walls thinner than 1mm😂😂 and the bottom is curbed towards inside to increase its surface 😂😂😂😂 Worse than not knowing/understanding something is to be convinced you know/understand when you don't. Even worse is to teach others wrong. This world is a big mess... I wonder 🤔 why 😂😂😂😂
i am listening to a radio program about Pascal right now and i wondered if this experiment was here.. i can't believe it! ..fantastic, thankyou for doing this 🙂 x
This answered the question I asked when I was in grade school back in the 1950's. So cool to see this. Perhaps I should have done my homework in high school...
It was demonstrated in my class and my student took it as well as a science experiment and fun. This is the great demonstration I have ever seen! Thanks to the authorities especially to the science teacher.
I don't know why this made me cry but thank you for this video. I couldn't find any other video about this specific experiment that Pascal did. Also, I am inspired that you are a woman in STEM.
Thanks for an excellent demonstration (and the follow-up explanation video) but equally for making into reality what was by all accounts just a thought-experiment before. Absolutely pioneering stuff and think this should be called the Visnjic barrel experiment, not the Pascal barrel, since all he did was sit in his dusty lab drawing it out instead of getting up there and inspiring people. I remember hearing about this when I took fluid mechanics as a course at uni decades ago, and I just couldn't accept what I was being told because it sounded so ridiclous....in the end I failed the class mainly because I hadn't developed the intuitive stuff that your experiment provides. The setup and execution of this was very impressive and while I did have the same confusion as a few others in that it appeared there might have been an air-tight seal between the syringe and the pipe, which had me scratching my head a bit, and this was partly obscured by the pressure gauge in the corner, I read a couple of other things about the experiment to understand what you were doing. This could of course be quickly clarified in the audio track although I imagine you are very busy. It is always fashionable for people to get excited about the latest technologies and developments but without a grasp of these basic physical things, no one can hope to understand them. By doing these clear and spectacular demonstrations you are helping to stem the tide of terrible pseudoscience and conspiracy that can only thrive when the basics are skipped and scientific terms are thrown around without knowledge of what they mean. It's absolutely vital work that you are doing and your enthusiasm is contagious. I also would like to add that I am disgusted at some of the dreadful sexist comments people have made on this video and it is truly shameful that you should have to put up with this, as you no doubt do throughout your career. Anyway, congratulations on this and no doubt many other future successes!
What about a slight alteration to the demonstration? Pre-fill the tube (above the mouth of the jar) and just raise it up to show how it's only the height that matters.
PyroChemist you are right why she did this.i dont believe that it works if we fill water before.because she is producing more pressure by pressing water there for the container broke
@@Physics4Life are you able to give electricity by using the atmospheric pressure changing by using the hydraulic pressure setup we use a long inverted test tube made of magnet and mercury and glass and copper wire coiled around the glass test tube filled with mercury and magnet neodymium magnet floating inside the tube we put all this setup inside the vacuum chamber and use hydrologic hydraulic pressure setup so we slightly changing pressure and it will provide momentum to many thousand magnet floating inside the vacuum chamber and give electricity so we got a simple electricity production units
so it implies we are not in high school delivery a laboratory demonstration it is much higher level to do this kinda of experiment ...which none of our polytechnics permit the physics lab or civil engineering laboratory to demonstrate that height matters . As we take a deep dive in the water pressure builds in all directions ...and oxygen depletes and similarly if you go to hill stations the atmospheric pressure decreases with height depleting oxygen. oxygen is so crucial for deep diving or sky divers jumping from a height . limiting oxygen supply at high altitude can cause exhaustion and breathing problems. There has been shortage of air supply at greater heights. I am neither manufacturer of oxygen or supplying oxygen and paying bills as high as these can be intercepted by higher authorities as I have no authorization whatsoever for conducting ....fluid mechanics or physics of UTM ..... How am I answerable when I am not authorized on such issues besides the rubber stamps with seal and signature with the physics /chemistry/civil HOD English Dept ? only God knows ? Vice president academics ? admission academics ? whosoever concerned for admission ?
I don't know who your high school physics teacher was, but as a public school teacher myself I can tell you it's not that teacher don't want to do a demonstration like this, it's we often don't have the resources -- that why this was done at a university -- deeper pockets.
I love it.. Pls explain other scientific laws in the same manner, as they were discovered first.. With less of modern tools and clutter, when you put it just as they were discovered, it becomes so intuitive and easy to understand... Thanks
It is interesting to consider that the pressure in the tube at the bottom is the same (approx) as the pressure that bursts the barrel, but the thin plastic tube can withstand it.
@@johnthehillboy7369 Glad to be of service! The pressure at the bottom of the tube is right at 1/2 psi per foot of column height. A pump at the top of a well can only draw the water up about 32 feet, because the 14.7 psi air pressure only pushes it up that far: call it 2 feet per psi or 1/2 psi per foot. The 150 foot column of water produces about 75 psi pressure at the bottom. If the tube is, say 1/2 inch in diameter, the surface area is about 1.5 (that is, pi/2) inches times the height we are worried about. That means every inch of the tube is feeling about 1.5 x 75 or about 110 lbs of pressure. The barrel at the bottom is not so lucky. It looks like it was about 2 feet (25 inches to make the numbers easy) across at the middle. Each inch of height is subjected to 25x75 psi...a bit under 2000 lbs of force per inch of height trying to tear the barrel apart. If the middle of the barrel is even 4 inches tall, that is about 8,000 lbs - *4 tons!* - of force. Glass has excellent tensile strength, but that is just too much.
Best demonstration I have seen of this counterintuitive result. Clearly reality is more complex and stuff like a earthquakes will move the water in the lake. and will generate forces that are related to the mass of water..
If you do this experiment again, use a double tube system. The first tube is the water vessel. The second tube is simply the vent. This principle is used in every structure in the world that possesses water drains. It will make the filling of the water tube a ton easier! Hope this helps! Edit: It occurred to me that even then you will not have an airless tube. You would have flow, but not necessarily enough to force all air downward. An easier method may be to install a bleeder valve at the bottom of the tube. Bleed the tube as if you would bleed the brakes on a car. You may lose a bit of water, but all air bubbles would be evacuated from the system. An additional method would be to prefill the vessel then fill the hose from the bottom through a valve via a pump. Pumps with output pressures in excess of 65 psi are widely available. Once the tube is filled, the valve can be closed. A second valve in the system can then be opened. And pressure would be diverted to the vessel.
1:54 For now I am calling bullschit on that. You would not feel the same pressure if there was only a thinner film of water. Without the rest of all that water of Lake Mead, which is also pressing vertically against it, then there would only be the smaller vertical pressure acting a force on it
You are my hero! I've always wanted a video of this experiment but no matter how hard I've tried I could never find one. It is also interesting to hear that perhaps Blaise didn't actually perform the experiment. I prefer to think of that as sour grapes from people like me who couldn't do it themselves because of all the obstacles that would have to be overcome.
Can you please explain why the pressure applied in fluids is transmitted to every other parts of fluid and in all directions....? It's an law but what happens microscopically and any intuition behind this law? And Why this property not seen in solids...
Cool demo, and I hope some materials students were included. Probably something to be learned about the properties of the glass, and design of the bottle, as well as pressure.
I really did think that hydrostatic pressure was a result of a combination of the width and depth of a volume of water. Amazing to be introduced to the idea that it isn't. as well as be offered proof.
The force (the weight) depends on the volume of water (F = rho*g*h*A if the tube cross-sectional area is A), but the pressure is force/area: P = F/A = rho*g*h.
A most excellent demonstration. I was personally curious as to how you got the water to go down the tube, where I learned that soap was the solution, but I also observed a lack of safety gear on the individual in the video, where they should be wearing some kind of retention mechanism to catch them in the event of a fall.
In order to make this demonstration easier to perform, add the following apparatus. Just above the safety enclosure, on the thin tube, install a Tee fitting so that the tail of the T is horizontal to the ground. The other two connections to the fitting remain attached to the bottle hose and the tall building hose in the vertical orientation. This third horizontal connection would now be open to the atmosphere. Make sure the bottle and hose are filled with fluid up to the Tee Fitting. Attach a Valve to open part of the Tee Fitting. The opening of this valve can be incredibly small, even a pin hole sized opening. You will no longer need soap or glycerin in the fluid. With the Valve open, pour the fluid from the tower into the long vertical hose from the top floor. All the air in the vertical column will be expelled via the T fitting and the valve opening. Once fluid reaches the T fitting and the valve, fluid will begin to escape through the small opening in the valve. Now close the valve. Please note: for safety reasons, the valve should either be closed with a stick from a short distance or electrically via a solenoid valve.
We considered this option, but did not want people to think that the barrel broke because of the impact of the downward falling water. It is purely a static (i.e. not moving) effect.
I love all the mess. Reminds me of school when you are trying to do in front of everyone something that worked just fine at home. Syringe falling apart was where I would scream and start cussing.
Wow, as scientist and diver love this experiment. Would have a bit of air on the top of the bottle and a second tube with an hydrophobic filter solved the bubble formation issue along the hose? The soap / syringe thing looks significant work and explanation to do. BTW, no idea that such a thick bottle could only handle 40 PSI, I guess is too big? I do experiments with soda bottles that can go over twice that.
That’s because it’s a misnomer and a very bad example. Volume absolutely matters in hydraulics, things like total dynamic head, flow rate, Venturi effect ect…this example she’s using is a terrible over simplistic comparison…here’s the simplest CORRECT explanation….the higher you go the more volume is between the start and end point which holds more fluid which weighs more which increases pressure…fluid density also plays a factor but that’s a whole other thing 😂
Also the way the experiment was demonstrated was also poorly thought out…simple math would have prevented the ejection of fluids simply by filling a reservoir with the required volume to fill the tube (this is math part) make the reservoir size x2 for expansion and fill it up all at once…I know this works because every liquid filled heat exchanger on the planet uses this to bleed air from the system
In order to prevent the soap water from regurgitating back to the opening, you feed in the water slowly instead of forcing it in with the syringe. The idea is to allow the water to flow in along the side of the tube keeping its center empty so that the air can escape out as water flows down to fill in the space.
3:44 The soap is what prevents the dyed water from coming back up by breaking the surface tension of the water. It's a 150 foot narrow tube. No matter how slowly you pour the water to travel down the inside of the tube, the surface tension from the hydrogen bonds will cause it to attract to itself and create the vapor lock. Besides, what method of filling the tube slowly along the side walls do you suggest that wouldn't take all day? Notice how the crowd dwindled waiting on the experiment in the first place. 4:48 Now imagine your drop by drop slow pour technique (that by the way is unnecessary with the addition of soap). How many people do you think would stand around for that?
@@mattmarzula when I was starting my house closed water system with well up on the hill.I brought some water down to my house and pump water from down up the pipe with valve near well allowing air to go out.After pumping,I closed down valve ,went up ,filled few scoops of water and closed air valve on the top.Voila, system works without any pump.Thats how fountains in Peterhof's park (Russia) work without pumps since 1703.Also without much soap drama could just fill pipe on the ground and pull one end up.
Demijons (the vessel destructed) are impressively thick at the neck and the bottom. They are however eggshell thin at the bottom quarter. Very nice demo.
The same principle - Pascal's Law - is the basis for how hydraulic devices work: 1) the hydraulic jack in an auto repair shop that only requires a small amount of hydraulic fluid to lift the car 2) hydraulic brakes in a vehicle, where only a tiny amount of hydraulic fluid can bring a 2 ton car to a stop from 60mph A physical analogy: you're cleaning the yard and ran out of large black plastic bags. You keep stuffing leaves into the bag. The incompressibility of the leaves is reach and the next handful of leaves you stuff in the plastic bag breaks it. While leaves are not an incompressible fluid, like a fluid, they can reach a point of 'no further compression is possible' just like a fluid has a limit .
Expecting something to happen and "believing" that it will happen are different. Expecting comes with learning and belief should be hard to come by in true science. History has shown this.
In your second attempt, place a fine feed inner tube within the main tube with a gap of at least a meter (the assumed volume of the inner tube translated to the diameters of the outer tube) and the top of the water . Pulls a weak vacuum on the outer tube. The vacuum will force any air pockets to move down and fill the mini hidden reservoir that it the gap between the end of the outer tube that fixed to the vassal and the end of the inner tube.
A three way valve just above the barrel enclosure to seal the 'straw' from the glass barrel while allowing water to bleed out of the straw to purge air bubbles. When the straw is full of just water turn the valve to allow the water to enter the glass barrel.
Greetings from India !! Excellent demonstration like never seen before !!! 😃 Really looking forward to view the upcoming videos. Dear madam, it would be really exciting to watch more such experiments on various concepts like surface tension, capillary rise, hydrostatic forces on bodies under water, buoyancy & what not !!! Regards ! 🙂
As you dive underwater (scuba) you do not feel the pressure because you are equalizing to ambient pressure. If you cannot clear (equalize) your oral/nasal passages to ambient, then yes you will feel the pressure. The same goes for lung volume using scuba, your lung volume will remain at the same volume at ambient pressure (the pressure of air you are breathing through your regulator/surrounding pressure) even if the water pressure is greater. It’s only when you breath-hold that your lungs will expand or contract. In any event, excellent presentation to demonstrate pascal’s law! I sure do miss physics class. Also, for preventing the tubing from blowing off the gauge, use a swage-lock fitting. They work well for high pressure applications.
This is a demonstration of Laplace's law that states that the wall tension of a hollow sphere or cylinder is proportional to both the pressure of its contents and its radius. Wall stress is the wall tension divided by 2 times the wall thickness. So if the tubing had been attached to glass tubing of the same size it would have survived.
The 17th century was the age of enlightenment, the birth of the scientific method. I'm pretty sure that Pascal did not need to do the experiment, he just did some deep thinking.
In the US we have a new way of teaching called NGSS in which the students are meant to be much more hands-on while learning. Nation-wide standards. Unfortunately, the entire topic of gas laws, including Boyles Law, was removed from the high school curriculum despite it's being the best suited to student experimentation. Proponents state that they're not mandated and that gas laws may be included, but that's just BS. People that know the beauty of the experiments retire and newbie teachers will stick to the approved list. They had to make room for Geology because the standards require 4 science classes while actual schools only schedule 3. Geniuses in charge.
There is a horizontal component to that force from the water against Hoover Dam since the water is stacked up down a hill ie the water at the back of the reservoir is shallower than at the front so the thin film is not equivalent.
I only just saw this. Great, but I have an idea for an improvement. have the pressurizing canister and long hose at ground level. Actually have canister level with top of flask. This will allow you to purge air from tube and make canister smaller. (Adds to dramatic effect)! Then slowly raise canister. BOOM! Same result, easier set up. This is not a criticism, it's what I initially thought you were going to do. Great video all the same, liked. belatedly.
Nice experiment. I told about Pascal experiment the last lesson and my students should tell me, if it is possible. I was thinking about that, how I could do the explose in my class, but I will prefer to show them your excellent video. :-)
The best part of this video was keeping in the mistakes, and showing that science isn't always perfect before it goes into the textbooks.
ur right, how many discoveries were/ are made through mistakes accidents etc.. it is very good and unusual of them to show this isn it..
Well... The water being pushed back was interesting, although the real reason was not explained. The liquid compressed the air that was inside the hose. So far, so correct. But the the liquid starts to flow down the edge of the hose while the air moves up slowly. At some point the water above the hose was not enough to keep the compression on the air.
Others were a little amateurish, too. Like a hose plopping off a barb in a demonstration of how strong pressure is... duh!
The best part was the clapping toddler at 6:02
Science is perfect, execution of theory is usually faulted
I found another aspect of this video to be the best part.
Another way to think about pressure depending on only the height of the water is to go to the edge of a lake, dig a small hole, make a channel connecting the two that's only a few centimeters deep, and then try damming that channel with your hand. The force of the water you're trying to hold back will feel negligible, even though there's a massive amount of water on the lake's side.
holy this is a GREAT analogy for dams. Thanks for sharing!
A really GOOD demonstration of a physical law/property. You can learn Pascal's law a hundred times, and even pass exams using it and its mathematical equations - but this short explanation followed by a pin-point "query to Mother Nature" with such a thin - even flexible tube, and so little extra water - will really do the job. People who watched this video will have the fact and physical law "nailed down" in their heads, part of their future intuition.
I admit to have been surprised, despite my BSc. in physics (ok, from 40 years ago...) my Intuition had it that the AMOUNT of water (hence its weight) had to do with the hydrostatic pressure. I really needed that reminder of Pascal's law and its meaning. I learned something here.
Thank you.
I love this professor. She's great and I can see how much fun it would be to learn in her class.
This was the only video I found about the topic. Thanks!
When you search the world for something that someone should have done long ago (and documented), but you find nothing... then you know you have got a gem. Cool video. I admire your perseverance.
Great demo! Honestly though, I think my favorite part was the bit about the technical challenges of this experiment - thank you so much for including that.
wait all the pressure on the dam wall comes from the height alone?
a narrow strip of water has the same pressure ??
what about the weight of all the water behind it, what holds that back?
@@hindugoat2302 think of your body. Your weight is felt on the bottom of your feet, not the sides of your legs, back, chest etc.
but a body is solid not fluid.
@@savage22bolt32
Fantastic experiment. That’s a real teacher right there.
And it does no harm that she's a dish!
I enjoy hearing her lectures and experiments, her voice is very pleasing to the ear.
That is so cool... I knew the physics of it, and understood that it should work, but it is still REALLY fascinating to see that thin tube of water breaking that big glass, purely because of the height of the water "column".
Shame that titan sub guy didn't watch this
I also understood that it should work but I wasn't sure how to actually do it. I wasn't sure there was plastic tubing that was strong enough (there is, I found some nylon tubing rated at 800 psi) or how to prevent bubbles from blocking the flow. I had various complicated ideas but adding soap wasn't one of them. Well done to whoever thought of that. One of my ideas was to suck the air out of the tube. Obviously more complicated than soap but I think that might have worked also.
@@davefoc Yeah, it seems like she did indeed end up at on of the simpler solutions for it. No matter which alternate solution I have thought of, they all end up being more complicated than the one she chose.
@@DanildFlamme It's normally easier to design a complex solution. Elegant solutions take more thought.
@@inyobill That's true... I guess that also says something about the politicians who makes a mess with super-complex laws 😆.
Nice demonstration of hydrostatic pressure.
P= density x gravitational force x height
I teach Physics to Anesthesiology students. That Hoover dam explanation was epic. I never realized that aspect. I learned something new today.
I'm really glad you had the foresight to dye the water in the tube. Notice that as soon as the vessel fails, it starts to fall, and the top of the vessel accelerates downwards at the expected 1 g. However, blue water immediately sprays in even faster than a simple 1 g acceleration from gravity could allow. This shows that the water has forces acting on it other than simple gravity- in particular, the spring-like elastic deformation of the tubing, and to some degree, the water itself (even though water is carelessly described as "incompressible", it does actually compress a very small amount). Without these forces, the top of the vessel and the blue water would have accelerated at the same rate and we would not have seen the blue puff.
There is no 1 g acceleration. The barrel expands slightly before it bursts, admitting some blue water.
@@gibbogleTry watching it at 0.25 speed from about 5:10. The glass breaks before any of the blue water injects in.
They don't mention it, but it's clear the person at the top of the tower is providing a good amount of pressure from the top of the tube with the syringe. They are pushing quite hard. This is technically "cheating" as it adds to the force of gravity in the tube. To really prove that it's "just" the height, you'd need to have an open tube. Bleeding the air from the bottom as you fill the tube would be a good idea too. Just add a small bleeder valve.
@@poleguy The syringe isn't sealed to the tube, so she isn't adding pressure directly.
I don't think you have to go to those effects to explain your observation. When the carboy bursts, the internal pressure drops to zero while the water in the tube is still at 43PSI so it squirts into the falling water just as it would into an open bucket.
Super very nicely explained and demonstrated. This type of videos should be shown in schools.
Amazing, thanks so much for doing this and then sharing it with the world.
I’ve never been so enthralled by an educational demonstration in my life
My thumb up is for this teacher. Because she is awesome!
I did a similar experiment the other direction. I dove into the deep end with the long pole we used to vacuum the pool. I put my hand over the tube so it wouldn't fill with water, then once at the bottom, I put my mouth on the end of the pole thinking it would work like a long snorkel. It almost sucked my lungs inside-out. Lol
Glad you're alright, you basically made a barometer with that set up. Lower pressure atmosphere compared to the pressure created by the depth of the water
Thanks for going to all of the trouble to make this demonstration! It's great to actually see a lesson, and not just learn it and accept it's probably true.
Wait till you find out that gravity doesn't exist and the reason stuff falls and rises is because of the medium. #MindBlown
I think the tube can also only be so long as the water at the top can boil due to pressure.. let me know if I’m missing anything
@@cryptokids3760 I know what you're talking about, but that also requires a vacuum to be present at the top of the tube.
Gostaria de ver a experiência invertida para uma descompressão abissal pois um tubo chegando às Fossas Marianas por exemplo deveria fazer jorrar água na superfície porque com o tubo não há a compressão lateral; caso positivo podemos projetar para esse fluxo uma usina elétrica;
Great experiment and very well executed! You did a good job dealing with all the challenges.
The only demonstration i could find online... Thank you!
Now I know excitement is another word for science. Thank you doctor.
Wow! This is a great demo. I had known that only the hight is the determining parameter, but I had not viscerally internalized that fact.
Never realized that the water pressure of a hose would suffice to generate the pressure to destroy a vessel.
Welldone! Excellent visualization. Thank you!
Why didn't the hydrostatic pressure burst the tube near the bottom. If it was able to break the glass, shouldn't it have been able to burst the plastic tubing?
Great question! The tube is actually much stronger than the glass - it is made out of a flexible polymer which is manufactured for strength and durability. We chose this strong tubing specifically so it would have a much higher pressure threshold than the glass, all part of the preliminary testing stages.
Volcanoes erupt where the earth is weaker
Because the large container wasn't super strong. The additional pressure was the straw that broke the camel's back.
1 - The pressure is at its highest at the bottom of the barrel.
2 - To break an object you need to apply a force that overcomes the forces that bound the atoms 😂
So p=F/A that means F=p*A😂
So if you have the same pressure on two containers the one that has bigger surfaces would be subjected to a higher force 😂😂😂
So, that makes a smaller container capable of handling higher pressures than a larger one even if they are built from the same material and have the same thickness of the walls 😂
3 - Increasing thickness of the walls makes a container capable of handling higher pressure 😂 that one with thinner walls even if they would have the same volume and are built from the same material 😂
4 - Most wrongly believe that the pressure is the same in all directions 😂 Completely false 😂 This is a little harder to grasp... Presure is caused by the atomic forces trying to reach a state of equilibrium... In short there is a specific distance that atoms like to keep from each other 😂 If you squeeze them they push back 😂 with the same force in any direction trying to get the space they like. 🤣🤣🤣 That means the presure is higher on the walls that have a smaller area even inside the same container... Now all this makes that a container that has a big length compared with its section area will actually have less pressure on the long walls than on the short ones... In other words in pipes with smaller diameter the pressure would be smaller on the transversal walls than on the walls on the ends of it. That means a tube that allows fluid to flow through it can handle a higher pressure if it has a smaller diameter.
And that's why the barrel breaks but not the hose. I bet the barrel would break even if the barrel and the hose would be built from the same material. 😂😂😂
Sorry for you... It's good to make since teaching fun, but too much circus distracts the attention from reality... Sorry for you all, but physics can't be truly learned before learning enough math...
This world is just a big freak show 😂😂😂😂
Ps
Consider how much pressure can handle a small aluminum beer can that has transversal walls thinner than 1mm😂😂 and the bottom is curbed towards inside to increase its surface 😂😂😂😂
Worse than not knowing/understanding something is to be convinced you know/understand when you don't.
Even worse is to teach others wrong.
This world is a big mess... I wonder 🤔 why 😂😂😂😂
@@wardeggerrobertmarius144 you need help
i am listening to a radio program about Pascal right now and i wondered if this experiment was here.. i can't believe it! ..fantastic, thankyou for doing this 🙂 x
This answered the question I asked when I was in grade school back in the 1950's. So cool to see this. Perhaps I should have done my homework in high school...
One of the best Physics videos in you tube
Incredible demo. Thank you for resurrecting that experiment.
It was demonstrated in my class and my student took it as well as a science experiment and fun. This is the great demonstration I have ever seen! Thanks to the authorities especially to the science teacher.
I don't know why this made me cry but thank you for this video. I couldn't find any other video about this specific experiment that Pascal did. Also, I am inspired that you are a woman in STEM.
Thanks for an excellent demonstration (and the follow-up explanation video) but equally for making into reality what was by all accounts just a thought-experiment before. Absolutely pioneering stuff and think this should be called the Visnjic barrel experiment, not the Pascal barrel, since all he did was sit in his dusty lab drawing it out instead of getting up there and inspiring people. I remember hearing about this when I took fluid mechanics as a course at uni decades ago, and I just couldn't accept what I was being told because it sounded so ridiclous....in the end I failed the class mainly because I hadn't developed the intuitive stuff that your experiment provides. The setup and execution of this was very impressive and while I did have the same confusion as a few others in that it appeared there might have been an air-tight seal between the syringe and the pipe, which had me scratching my head a bit, and this was partly obscured by the pressure gauge in the corner, I read a couple of other things about the experiment to understand what you were doing. This could of course be quickly clarified in the audio track although I imagine you are very busy.
It is always fashionable for people to get excited about the latest technologies and developments but without a grasp of these basic physical things, no one can hope to understand them. By doing these clear and spectacular demonstrations you are helping to stem the tide of terrible pseudoscience and conspiracy that can only thrive when the basics are skipped and scientific terms are thrown around without knowledge of what they mean. It's absolutely vital work that you are doing and your enthusiasm is contagious.
I also would like to add that I am disgusted at some of the dreadful sexist comments people have made on this video and it is truly shameful that you should have to put up with this, as you no doubt do throughout your career. Anyway, congratulations on this and no doubt many other future successes!
Imagine saying that Pascal didn't inspire people. Just read what Nietzsche had to say about him.
What about a slight alteration to the demonstration? Pre-fill the tube (above the mouth of the jar) and just raise it up to show how it's only the height that matters.
Yes, that would work as well!
PyroChemist you are right why she did this.i dont believe that it works if we fill water before.because she is producing more pressure by pressing water there for the container broke
thats brilliant. that way u dont need to worry about all the surface tension.
@@Physics4Life are you able to give electricity by using the atmospheric pressure changing by using the hydraulic pressure setup
we use a long inverted test tube made of magnet and mercury and glass and copper wire coiled around the glass test tube filled with mercury and magnet neodymium magnet floating inside the tube
we put all this setup inside the vacuum chamber and use hydrologic hydraulic pressure setup so we slightly changing pressure and it will provide momentum to many thousand magnet floating inside the vacuum chamber and give electricity so we got a simple electricity production units
@@derek8541 It's not air pressure from the tiny syringe, it's additional hydraulic pressure being exherted on the glass container.
I wish we'd had experiments like this when I was in high school (a long time ago). Seeing physics and mathematics in action really helps.
so it implies we are not in high school delivery a laboratory demonstration it is much higher level to do this kinda of experiment ...which none of our polytechnics permit the physics lab or civil engineering laboratory to demonstrate that height matters . As we take a deep dive in the water pressure builds in all directions ...and oxygen depletes and similarly if you go to hill stations the atmospheric pressure decreases with height depleting oxygen. oxygen is so crucial for deep diving or sky divers jumping from a height . limiting oxygen supply at high altitude can cause exhaustion and breathing problems. There has been shortage of air supply at greater heights. I am neither manufacturer of oxygen or supplying oxygen and paying bills as high as these can be intercepted by higher authorities as I have no authorization whatsoever for conducting ....fluid mechanics or physics of UTM ..... How am I answerable when I am not authorized on such issues besides the rubber stamps with seal and signature with the physics /chemistry/civil HOD
English Dept ? only God knows ?
Vice president academics ? admission academics ?
whosoever concerned for admission ?
I don't know who your high school physics teacher was, but as a public school teacher myself I can tell you it's not that teacher don't want to do a demonstration like this, it's we often don't have the resources -- that why this was done at a university -- deeper pockets.
I've been using this video in my Physics with Calc college class for a few years. Now I'm going further and using it as a Canvas video quiz.
I love it..
Pls explain other scientific laws in the same manner, as they were discovered first..
With less of modern tools and clutter, when you put it just as they were discovered, it becomes so intuitive and easy to understand...
Thanks
Awesome idea for a channel. Hands-on showing students how science really works. Thanks for sharing!!!
Every STEM teacher should start every lecture with this quote from Adam Savage of Mythbusters. "Failure is always an option"
Wish I had had teachers like that who could Teach a lesson and keep ALL interested ...
Congratulations. Very nice experiment. Specially because of what was not hidden under the rug. I will use it with my students here in Brazil. Thanks!
It is interesting to consider that the pressure in the tube at the bottom is the same (approx) as the pressure that bursts the barrel, but the thin plastic tube can withstand it.
Yes, I would like to understand that better. Someone please explain 🙏
@@johnthehillboy7369 Glad to be of service! The pressure at the bottom of the tube is right at 1/2 psi per foot of column height. A pump at the top of a well can only draw the water up about 32 feet, because the 14.7 psi air pressure only pushes it up that far: call it 2 feet per psi or 1/2 psi per foot.
The 150 foot column of water produces about 75 psi pressure at the bottom. If the tube is, say 1/2 inch in diameter, the surface area is about 1.5 (that is, pi/2) inches times the height we are worried about. That means every inch of the tube is feeling about 1.5 x 75 or about 110 lbs of pressure.
The barrel at the bottom is not so lucky. It looks like it was about 2 feet (25 inches to make the numbers easy) across at the middle. Each inch of height is subjected to 25x75 psi...a bit under 2000 lbs of force per inch of height trying to tear the barrel apart. If the middle of the barrel is even 4 inches tall, that is about 8,000 lbs - *4 tons!* - of force. Glass has excellent tensile strength, but that is just too much.
A great teacher with intelligent ideas! Well done.
Thank you so much for doing this experiment!
Best demonstration I have seen of this counterintuitive result. Clearly reality is more complex and stuff like a earthquakes will move the water in the lake. and will generate forces that are related to the mass of water..
Wow, this is amazing. I'm looking forward to the next videos!
I feel like I won just watching this beautiful woman's demonstration
wow,looking forward for other videos as well
What a great teacher!
An excellent demonstration!
I am so proud of the team work
If you do this experiment again, use a double tube system. The first tube is the water vessel. The second tube is simply the vent. This principle is used in every structure in the world that possesses water drains. It will make the filling of the water tube a ton easier! Hope this helps!
Edit:
It occurred to me that even then you will not have an airless tube. You would have flow, but not necessarily enough to force all air downward. An easier method may be to install a bleeder valve at the bottom of the tube. Bleed the tube as if you would bleed the brakes on a car. You may lose a bit of water, but all air bubbles would be evacuated from the system.
An additional method would be to prefill the vessel then fill the hose from the bottom through a valve via a pump. Pumps with output pressures in excess of 65 psi are widely available. Once the tube is filled, the valve can be closed. A second valve in the system can then be opened. And pressure would be diverted to the vessel.
love that you can see the soapy water flowing into the bottle while the bottle is collapsing
You are a great teacher and it would be so awesome if had more such amazing content of your channel.
Love this video. All good data is important. Especially observable surprises such as in take one. Fun fun.
Thanks for this video, I show this in my class.
Very Cool!! My physics teacher showed us this and it blew my socks off!!
You are such a great presenter of science!
This is the most interested I've ever been in a physics professor ... I mean in physics before.
Her optimism, perkiness and cuteness reminds me of Pam from “The Office”
u did a lot of hard work, i didn't think this would be this hard
1:54 For now I am calling bullschit on that. You would not feel the same pressure if there was only a thinner film of water. Without the rest of all that water of Lake Mead, which is also pressing vertically against it, then there would only be the smaller vertical pressure acting a force on it
Brilliant video and demo.
You are my hero! I've always wanted a video of this experiment but no matter how hard I've tried I could never find one. It is also interesting to hear that perhaps Blaise didn't actually perform the experiment. I prefer to think of that as sour grapes from people like me who couldn't do it themselves because of all the obstacles that would have to be overcome.
Ma'am you are amazing!!!! I wish I could have teacher like you.
I wish I'd had teachers like her when I was in school; I might not have turned out to be such a failure 😅
Don’t say failure. You are not. But I say the same thing except that I might not have turned into such a bone head.
A great experiment, showing us the magic that physics brings
Reminds me of watching Professor Julius Sumner Miller on TV, when I was a child. Good memories.
Can you please explain why the pressure applied in fluids is transmitted to every other parts of fluid and in all directions....? It's an law but what happens microscopically and any intuition behind this law? And Why this property not seen in solids...
Yes! This is explained in the part II: ruclips.net/video/6zeHWVUiXoc/видео.html
Cool demo, and I hope some materials students were included. Probably something to be learned about the properties of the glass, and design of the bottle, as well as pressure.
I really did think that hydrostatic pressure was a result of a combination of the width and depth of a volume of water. Amazing to be introduced to the idea that it isn't. as well as be offered proof.
The force (the weight) depends on the volume of water (F = rho*g*h*A if the tube cross-sectional area is A), but the pressure is force/area: P = F/A = rho*g*h.
fun and explanatory, good job...
A most excellent demonstration. I was personally curious as to how you got the water to go down the tube, where I learned that soap was the solution, but I also observed a lack of safety gear on the individual in the video, where they should be wearing some kind of retention mechanism to catch them in the event of a fall.
In order to make this demonstration easier to perform, add the following apparatus. Just above the safety enclosure, on the thin tube, install a Tee fitting so that the tail of the T is horizontal to the ground. The other two connections to the fitting remain attached to the bottle hose and the tall building hose in the vertical orientation. This third horizontal connection would now be open to the atmosphere. Make sure the bottle and hose are filled with fluid up to the Tee Fitting. Attach a Valve to open part of the Tee Fitting. The opening of this valve can be incredibly small, even a pin hole sized opening. You will no longer need soap or glycerin in the fluid. With the Valve open, pour the fluid from the tower into the long vertical hose from the top floor. All the air in the vertical column will be expelled via the T fitting and the valve opening. Once fluid reaches the T fitting and the valve, fluid will begin to escape through the small opening in the valve. Now close the valve. Please note: for safety reasons, the valve should either be closed with a stick from a short distance or electrically via a solenoid valve.
We considered this option, but did not want people to think that the barrel broke because of the impact of the downward falling water. It is purely a static (i.e. not moving) effect.
I love all the mess. Reminds me of school when you are trying to do in front of everyone something that worked just fine at home. Syringe falling apart was where I would scream and start cussing.
Wow, as scientist and diver love this experiment. Would have a bit of air on the top of the bottle and a second tube with an hydrophobic filter solved the bubble formation issue along the hose? The soap / syringe thing looks significant work and explanation to do. BTW, no idea that such a thick bottle could only handle 40 PSI, I guess is too big? I do experiments with soda bottles that can go over twice that.
Excellent demonstration very well explained! Thank you very much for the effort! really appreciated!
i didn't understand the hoover dam example
That’s because it’s a misnomer and a very bad example. Volume absolutely matters in hydraulics, things like total dynamic head, flow rate, Venturi effect ect…this example she’s using is a terrible over simplistic comparison…here’s the simplest CORRECT explanation….the higher you go the more volume is between the start and end point which holds more fluid which weighs more which increases pressure…fluid density also plays a factor but that’s a whole other thing 😂
Also the way the experiment was demonstrated was also poorly thought out…simple math would have prevented the ejection of fluids simply by filling a reservoir with the required volume to fill the tube (this is math part) make the reservoir size x2 for expansion and fill it up all at once…I know this works because every liquid filled heat exchanger on the planet uses this to bleed air from the system
This demo is amazing
You're a very very good teacher
Physics works! More people should see this video.
In order to prevent the soap water from regurgitating back to the opening, you feed in the water slowly instead of forcing it in with the syringe. The idea is to allow the water to flow in along the side of the tube keeping its center empty so that the air can escape out as water flows down to fill in the space.
3:44 The soap is what prevents the dyed water from coming back up by breaking the surface tension of the water. It's a 150 foot narrow tube. No matter how slowly you pour the water to travel down the inside of the tube, the surface tension from the hydrogen bonds will cause it to attract to itself and create the vapor lock. Besides, what method of filling the tube slowly along the side walls do you suggest that wouldn't take all day? Notice how the crowd dwindled waiting on the experiment in the first place. 4:48 Now imagine your drop by drop slow pour technique (that by the way is unnecessary with the addition of soap). How many people do you think would stand around for that?
@@mattmarzula when I was starting my house closed water system with well up on the hill.I brought some water down to my house and pump water from down up the pipe with valve near well allowing air to go out.After pumping,I closed down valve ,went up ,filled few scoops of water and closed air valve on the top.Voila, system works without any pump.Thats how fountains in Peterhof's park (Russia) work without pumps since 1703.Also without much soap drama could just fill pipe on the ground and pull one end up.
Demijons (the vessel destructed) are impressively thick at the neck and the bottom. They are however eggshell thin at the bottom quarter. Very nice demo.
The same principle - Pascal's Law - is the basis for how hydraulic devices work:
1) the hydraulic jack in an auto repair shop that only requires a small amount of hydraulic fluid to lift the car
2) hydraulic brakes in a vehicle, where only a tiny amount of hydraulic fluid can bring a 2 ton car to a stop from 60mph
A physical analogy: you're cleaning the yard and ran out of large black plastic bags. You keep stuffing leaves into the bag. The incompressibility of the leaves is reach and the next handful of leaves you stuff in the plastic bag breaks it.
While leaves are not an incompressible fluid, like a fluid, they can reach a point of 'no further compression is possible' just like a fluid has a limit
.
Expecting something to happen and "believing" that it will happen are different.
Expecting comes with learning and belief should be hard to come by in true science.
History has shown this.
I didn't grok the height/pressure thing until I was reminded that pressure is _force per unit area_ . That's what finally clicked for me.
surprisingly that plastic water tube is so resistant to pressure -)
In your second attempt, place a fine feed inner tube within the main tube with a gap of at least a meter (the assumed volume of the inner tube translated to the diameters of the outer tube) and the top of the water . Pulls a weak vacuum on the outer tube. The vacuum will force any air pockets to move down and fill the mini hidden reservoir that it the gap between the end of the outer tube that fixed to the vassal and the end of the inner tube.
A three way valve just above the barrel enclosure to seal the 'straw' from the glass barrel while allowing water to bleed out of the straw to purge air bubbles. When the straw is full of just water turn the valve to allow the water to enter the glass barrel.
Greetings from India !!
Excellent demonstration like never seen before !!! 😃
Really looking forward to view the upcoming videos.
Dear madam, it would be really exciting to watch more such experiments on various concepts like surface tension, capillary rise, hydrostatic forces on bodies under water, buoyancy & what not !!!
Regards ! 🙂
As you dive underwater (scuba) you do not feel the pressure because you are equalizing to ambient pressure. If you cannot clear (equalize) your oral/nasal passages to ambient, then yes you will feel the pressure. The same goes for lung volume using scuba, your lung volume will remain at the same volume at ambient pressure (the pressure of air you are breathing through your regulator/surrounding pressure) even if the water pressure is greater. It’s only when you breath-hold that your lungs will expand or contract. In any event, excellent presentation to demonstrate pascal’s law! I sure do miss physics class. Also, for preventing the tubing from blowing off the gauge, use a swage-lock fitting. They work well for high pressure applications.
This is a demonstration of Laplace's law that states that the wall tension of a hollow sphere or cylinder is proportional to both the pressure of its contents and its radius. Wall stress is the wall tension divided by 2 times the wall thickness. So if the tubing had been attached to glass tubing of the same size it would have survived.
Great job guys am glad I stayed in school 🎒 love science class
The 17th century was the age of enlightenment, the birth of the scientific method. I'm pretty sure that Pascal did not need to do the experiment, he just did some deep thinking.
Excellent demonstration!! That's how physics is to be taught👍
In the US we have a new way of teaching called NGSS in which the students are meant to be much more hands-on while learning. Nation-wide standards. Unfortunately, the entire topic of gas laws, including Boyles Law, was removed from the high school curriculum despite it's being the best suited to student experimentation. Proponents state that they're not mandated and that gas laws may be included, but that's just BS. People that know the beauty of the experiments retire and newbie teachers will stick to the approved list.
They had to make room for Geology because the standards require 4 science classes while actual schools only schedule 3. Geniuses in charge.
There is a horizontal component to that force from the water against Hoover Dam since the water is stacked up down a hill ie the water at the back of the reservoir is shallower than at the front so the thin film is not equivalent.
I might have liked physics more if she were my teacher...
i like how she tops the jug off super precisely and then just stuffs a tapered plug in and gushes the excess out lol
I only just saw this. Great, but I have an idea for an improvement.
have the pressurizing canister and long hose at ground level. Actually have canister level with top of flask. This will allow you to purge air from tube and make canister smaller. (Adds to dramatic effect)!
Then slowly raise canister. BOOM! Same result, easier set up.
This is not a criticism, it's what I initially thought you were going to do.
Great video all the same, liked. belatedly.
Interesting about the thin layer of water against the Hoover dam exerting the same pressure against it as the whole lake.
Obviously how thin is important - just wetting the surface wouldn't exert the same pressure.
00:35 "We have faith in physics", *this* should be printed on dollar bills if anything.
Difficulties must be public. For the very reason you state! Bravo you be thinkin right. Sheesh!
Nice experiment. I told about Pascal experiment the last lesson and my students should tell me, if it is possible. I was thinking about that, how I could do the explose in my class, but I will prefer to show them your excellent video. :-)