Hydrostatic Pressure (Fluid Mechanics - Lesson 3)

A description of hydrostatic pressure, along with the equation to calculate it, and an example.

[@kingsleyukaulor3704]

This is very clever. Absolutely brilliant. Thanks for your help.

[@lh776]

Very helpful, thank you for doing this video.

[@StrongMed]

In most communities, the local water company has placed a large water tank either in a high tower or on top of a hill, and gravity provides the pressure to the individual homes (much like the example in the video). To change your home's water pressure, my first recommendation is to consult a professional plumber. If you're a do-it-yourself kind of person, then check out the KZbin video "Test and Adjust Your Home's Water Pressure" or search for "increase water pressure" on Wikihow.

[@irdeena918]

oh yes . i remember i learnt this last year . ugh . too bad i didnt pay any attention to my physic teacher when he explained it . btw , great video !!

[@TheBobby416]

I did. And just forgot. 8 grade. I like fish tanks. And fish tanks need pumps. Nice to see I am not the only one. Little smile

[@osteogenesiscongenita7600]

I've seen some of your videos and you have really good taste in music.

[@StrongMed]

...The question as to whether one could power a home using just water pressure through your water main is an interesting one that I've never considered before. If you ran every faucet in your home 24/7, and using turbines, had the water continuously charge high capacity batteries that could provide transient increases in power when using something like a computer or TV, I suspect it's possible. But the water waste would be enormous, and it would not be remotely cost effective.

[@StrongMed]

It probably uses gravity only - sort of. The water company may still require other means to get the water up into the high tank to begin with, unless the community's water source happens to naturally be at a high elevation (like you might see in the foothills of the Sierra Nevada. Every local water company is a little different based on geography, water source, number of customers, types of residences, etc...

[@1105comfortablynumb]

Very concise. Thanks

[@StrongMed]

...also, to increase the water pressure in your home, if other steps don't solve the problem, you can install something called a "pressure booster". However, these are expensive, should only be installed by someone experienced with them, and local laws may require it to be inspected after instillation. Good luck!

[@elrojoJazz]

Great lesson! Question on water pressure. Where does the water pressure come from in a common house or neighborhood. And is there a way to make my house have more or less water pressure? Does the water company supply the pressure?

[@minrvahiedra]

So concise 👌👌👌

[@safaesafae6041]

Very helpful Thanks

[@vijay85321]

So good

[@anxhelo8649]

thank you!

[@nataliamatos4503]

I don't understand though, why is only the height relevant, when P=F/A??

[@m0anyx]

height determines gravitational force, changing F

[@elrojoJazz]

Actually I was thinking more on the lines of mini tesla turbines hooked right to your home water pipes, both hot and cold. Every time you take a shower. run the dishwasher, laundry or toilets. the mini turbines would generate power back to the electric grid. So no extra water would be wasted. How ever..you probably could not generate enough power to run your house on it. But still you would get paid to shower,clean laundry and go to the bathroom. haha :)

[@shilimkarnv1]

Very nice explanation

[@haryakumuda6798]

Is the buoyancy force the reaction of hydrostatic pressure?

[@shaddadkarimmanea1065]

great

[@tahahassanmohammedelshikh9354]

Thank you

[@andrewty6339]

final answer for the question is 628,937 Pa if anyone was wondering. ( 1 atm = 101,325 Pa)

[@SuperKuku24]

Great video but I have a question wouldnt the change in height be 54 - 50 =4 .....Explain please

[@StrongMed]

The change in height (i.e. delta h) is the difference between the column of fluid's maximum height, and the height at which it's pressure is being measured. The question implies that the house's water pressure is being measured at a height equal to where the pipe enters the wall. If the pressure was being measured coming out of a shower on the second floor, and the shower faucet was 5 meters above where the pipe entered the house, the delta h would be 50 + 4 - 5 = 49. This is why the water pressure in a building is always higher on the lower floors than the upper, though it is usually only noticeable when the water pressure throughout is very low to begin with.

[@scarr2731]

Great 'splaining

[@dianaivanova5294]

Hi, could you explain to me why we took 54 meters into consideration and not only 4 meters? Because you're counting in your formula the hydrostatic pressure at the house to be the same as if the container with water was 54 meters high and directly vertically connected to the house. I'm not sure if I'm clear enough but imagine this - you have 54 meters high container full of water, and then for sure the hydrostatic pressure at the bottom would be the whole distance from bottom to the top (atmosphere). In this case we could put 54 meters in the formula and it would be correct. If the house was connected by direct horizontal pipe to the bottom of the container, it's hydrostatic water pressure would equal the '54 meter high' weight of water. But in this case where the house is connected by a thin pipe (let's ignore it's inside volume of water since pipe would be very thin for better imagination, so also the weight of water solely in the pipe would be so small it can be ignored in the calculation of hydrostatic pressure) to the bottom of a 4 meter high container of water, why the hydrostatic pressure in the pipe is not equal to the weight of the 4 meters of water? Why do you count also the distance of air (not density of water) between the container and the house, the 50 meters? Because then the 54 meter high container full of water would cause exact same pressure on the house pipe than the 4 meter container which surely is not correct since there are many many more molecules and the mass of water and weight is much higher. And second reason also is that if you count air distance from the bottom of container to the house just because this tiny tube connects them, it would mean that 4 meter high container of water would create 100x bigger difference in pressure on the house pipe when being on the house level versus when being on level 100 meters above the house. Which is non sense to my understanding. But I may be wrong so please explain. I cant get my brain through this.

[@StrongMed]

In other words, using water to power your home would be like setting up a personal hydroelectric plant. However, the huge difference in scale, and use of clean potable water (which costs money), would make this not economical. (Although it would be an awesome science project...)

[@hotdog6758]

How does a hydrostatic pressure in giraffe's body looks like ?

[@elrojoJazz]

Hmm... So you are saying that every home in my area code.uses water pressure that is powered by gravity only? Thats amazing! I thought the water company would need a pressure booster? or power waterturbine? If the pressure is all gravity. Thats free energy right?... could you power are home on water pressure?

[@twominuteanaesthesia]

Good stuff

[@michaelkingssa]

Hi what's the song in the intro??

[@stxnw]

Why did you minus the water pressure of the house with the atmospheric pressure.

[@nyx211]

Because in this case, we only care about the gauge pressure (Δp), not the absolute pressure.

[@hamedhosseini4938]

is distinction enough mark to get into medicine in uni? :(

[@rolandjosephdraper3884]

thanks

[@shashanksingh6601]

Nice lcr

[@sofiannothere]

i’m 11 i just try getting ahead in every subject tho so here we go🏃‍♀️🏃‍♀️🏃‍♀️

[@PHOENIXTURF]

Am 13 am doing the same thing

[@gaminggods8235]

what are the pressures you i have had pain its not that easy to focus on something when you have pain you don't know how its like to have pain and focus on something this is first time for me to learn something like this ,it may get delay

[@r.k.mandal25]

o! I remember......

[@homershomie01]

relatively low and relatively high are not a measurement at all. you should just say greater than or less than if that's your analogy is true. or it's just an non arbitrary admittedly relative observationly opinion. but I love the video . thank you for making the video

[@TheSquidly1]

0:55 this surely proves how force can bend something. imagine time-space being bent! :D

[@deathmetalcoffee]

+ann nonomous Especially with black holes, I bet they have enough mass to do so.

[@TheBobby416]

Is the matter, or the lack of matter.? As a pump. Mass and gravity. Both increase with one another. Correct.

[@Bel...QWERTY1]

why hydrostatic pressure is perpendicular to surfaces???

[@yashwanthsrk]

can you please explain ,why you took 1000kg^3*9.8 at the house's pressure problem?

[@minaswetmir7091]

They are two constants , Density of fluids is 1000kg/m^3 And 9.8 is the constant of gravity

[@yashwanthsrk]

Thank you, I got confused because it is not given as a constant in the problem.@@minaswetmir7091

[@mr_sher1749]

at 7mins in your video when you have your equation to calculate Phouse. I think you are wrong there, you have your minuses wrong...if you are saying Phouse - Patm (P2-P1) = pgdh...(dh = -54m ; Z2-Z1) so you either do it as Phouse = Patm - pg(54m) OR Phouse = Patm + pg(-54m).

[@anilsharma-ev2my]

So we found time for any event in the universe so it's show how longer something exist and we are just the function of time🕉🕉🕉🕉

[@heavencat6674]

7:15 why isn't Patm -- Phouse

[@rajaryangupta9756]

Give a like if you are a vnit student from chemical engineering and watching this video and comment your batch year if you are aslo suggest by sachin sir 😂

[@balashowreddy4529]

E

[@brianmckerrow817]

10m = 1 bar 5.4 would be 5.4 bar

[@jake9674]

This is wrong. A person sitting in a barrel of water would not be crushed by hydrostatic pressure by the mere adding of a long thin straw of water connecting to the top of the barrel. You are ignoring the area of water above when calculating Hydrostatic pressure and only considering height.

[@StrongMed]

I'm not exactly sure I totally understand your disagreement here since there are no barrels discussed in the video. However, imagine a hypothetical situation in which there is a barrel on the ground of near infinite strength (because otherwise it would burst) and a mile long sealed straw extending upwards from the barrel and the entire system is sealed and filled with water. And it's sitting next to a barrel of same diameter but the barrel itself is a mile tall - the pressure at the very bottom of the both systems will be the same. A good explanation with diagrams and derivations of this concept (as well as an interesting thought experiment about perpetual motion machines that would be possible if the shape of the container mattered): www.tec-science.com/mechanics/gases-and-liquids/pressure-in-liquids-hydrostatic-pressure/ This counterintuitive principle is known as the Hydrostatic Paradox. It's been described as early as the 1860s (though not very clearly IMHO: www.scientificamerican.com/article/the-hydrostatic-paradox/

[@jake9674]

@@StrongMed Your example is exactly what I am referring to, and demonstrates precisely how you are incorrect. In the Ocean where pressure is equalized you can use the short-hand calculation which only relies on height. But this is not correct in all scenarios. In the example with the barrel, imagine we continue to make the straw thinner and thinner. At a certain point, you are arguing that a person could be crushed by Hydrostatic pressure due to less than a pound of water. This is a widespread inaccuracy, even found in many textbooks. I became so curious on the question I actually contacted a friend-of-a-friend who has PhD in physics who explained it to me. I'm not going to try to explain all the Math in the space of a youtube comment (I would probably get it wrong anyways), but I would ask you to reply to my above example. Could a person in a barrel be crushed by a extremely small amount of water, were the water to be placed in a thin straw above the barrel? If so, where is this pressure coming from? How could you be crushed by an amount of water so small you would be able to easily lift it? Conduct a real experiment, I guarantee you will find out your formula is wrong.

[@StrongMed]

The reason it's called a paradox is because it contradicts what "common sense" tells us should happen. You refer to my explanation as a "widespread inaccuracy" - yes, widespread enough to be found in every physics textbook ever written. If your friend's friend with the physics PhD said you were correct, either they didn't understand your question, or you didn't understand their answer. Here's a great video that explains the paradox, and includes a "real experiment" at the end which demonstrates the exact point I made above: kzbin.info/www/bejne/bKvIeYqMis6LpcU (In short, yes, a person could be crushed to death by an extremely small volume of water, if it was in the form of an extremely tall tube.)

[@jake9674]

​@@StrongMed Edit - deleted my comment. You are right.

[@PenandPaperScience]

@@StrongMed It is indeed a very hard concept to grasp, and explain! I like your explanation! :)

[@tGoldenPhoenix]

Thank you