What is Hydrostatic pressure: Definition and 100 Discussions

Fluid statics or hydrostatics is the branch of fluid mechanics that studies "fluids at hydrostatic equilibrium and the pressure in a fluid or exerted by a fluid on an immersed body".It encompasses the study of the conditions under which fluids are at rest in stable equilibrium as opposed to fluid dynamics, the study of fluids in motion. Hydrostatics is a subcategory of fluid statics, which is the study of all fluids, both compressible or incompressible, at rest.
Hydrostatics is fundamental to hydraulics, the engineering of equipment for storing, transporting and using fluids. It is also relevant to geophysics and astrophysics (for example, in understanding plate tectonics and the anomalies of the Earth's gravitational field), to meteorology, to medicine (in the context of blood pressure), and many other fields.
Hydrostatics offers physical explanations for many phenomena of everyday life, such as why atmospheric pressure changes with altitude, why wood and oil float on water, and why the surface of still water is always level.

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  1. L

    Fluid Dynamics - Hydrostatic Pressure

    Homework Statement A rectangular vertical plate is submerged in water. The top edge is horizontal and at a depth of 0.6m. The length of the vertical edge is 1.2m. determine at what dept under the water surface a horizontal line can be drawn on the plate such that the hydrostatic forces on...
  2. Rectifier

    Hydrostatic pressure - barrel vs. small cylinder of water

    This problem was translated from Swedish, sorry for any grammatical errors present. The problem The grey is liquid is water. The small container is a pipe made of glas and the big container is a barrel. Water is poured into the glas pipe. When water reaches 12m over the barrel top(lid) the...
  3. K

    Hydrostatic pressure and Gravitational Potential Energy

    So say I had a glass of water on a table ,with the glass filled to the top. The bottom of the glass, the water would have a higher pressure than the top of the glass. This is the concept of hydrostatic pressure etc. But how does GPE fit into all of this? Does the water at the top of the glass...
  4. Jason Onwenu

    Hydrostatic Pressure Question?

    Homework Statement During a test dive in 1939, prior to being accepted by the U.S. Navy, the submarine Squalus sank at a point where the depth of water was 73.0 m. The temperature at the surface was 27.0 ∘C and at the bottom it was 7.0 ∘C. The density of seawater is 1030 kg/m3. A diving bell...
  5. gracy

    Hydrostatic pressure of glomerular capsule

    Effective filtration pressure is produced by 1-blood pressure in blood capillaries which is about 55mmHg. 2-The osmotic pressure of blood which is 30 mm Hg 3-hydrostatic pressure of glomerular capsule which is 10 mm Hg blood pressure in blood capillaries and the osmotic pressure of blood I...
  6. Feodalherren

    Fluid Mechanics: Hydrostatic Pressure on a gate with hinges

    Homework Statement Homework Equations Fluid Mechanics The Attempt at a Solution Lets start with the easy part: The pressure of the air is constant so the pressure will act as if it's a concentrated force on the center of gravity of the gate. F = PA = (10,000Pa)(.3)(.6)=1800N The moment...
  7. Soumalya

    Hydrostatic pressure distribution for an ideal gas

    Considering a unit mass of an ideal gas in a cylindrical container of volume 'V' at temperature 'T' the pressure exerted by the gas at the walls of the container is given by the ideal gas equation as, pV=RT where 'R' is the characteristic gas constant for the particular gas. Under equilibrium...
  8. T

    Hydrostatic Pressure on Curved Circular Surface

    Homework Statement Picture:[/B] The Attempt at a Solution [/B] Can someone please help..There's no answers and I think my answer is very wrong, as you can see I have pretty much no idea what I'm doing. Thanks Edit: Where it says net force I meant to say net force per unit width. Edit2...
  9. B

    Hydrostatic pressure and consequences of pascal's law

    I've had a doubt about the following (somewhat contradictory) statements. 1) pressure applied to an incompressible fluid is equally transmitted at all points. 2) pressure at points at different heights in a fluid placed in a container in a gravitational field are different. Gravity applies a...
  10. J

    How Does Centroid Affect Hydrostatic Pressure Calculation?

    Homework Statement Can you please help me I think I have confused something.We did this in class. A triangular plate with base = 10 m and height 12 m is placed under water with the base at the top at a depth of 8 meters under water and the apex 20 meters under water. Find the hydrostatic...
  11. R

    Hydrostatic pressure and the reading on a scale

    http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/weighing-buoyancy/So I was wondering if both the scales would show the same weight value? (the scales are marked black in the picture) The object on the left is a pyramid and the object on the right is a cube. They are both...
  12. F

    Hydrostatic Pressure: Radial Inwards vs Outwards

    Hydrostatic pressure is exerted in all directions but what determines whether it acts radially inwards or radially outwards. For example, if you are a diver you feel pressure from the water acting inwards, giving you a crushing sensation. However, if you fill a balloon full of water and poke...
  13. H

    Hydrostatic Pressure: Height vs Volume

    Why in hydrostatic pressure we care about height and not about volume? For example if we have into a thin and a thick tube water in the same height,why both tube have the same pressure?? Is wrong to say that the more water makes the bigger pressure? If yes,why?
  14. H

    Law of Hydrostatic Pressure: What is the Significance of Height?

    Law of hydrostatic pressure is: Ph=p*h*g. That what I do not undestand is,why we care about the height? Thanks.
  15. W

    When should we use p = ρ.g.h and p = ρ.g.hcg for hydrostatic pressure?

    For the hydrostatic pressure, when do we use [ p = ρ.g.h ] and [ p = ρ.g.hcg ] where: ρ = density g = acc of gravity h = height of water column hcg = the distance to the center of gravity from the surface of water downward
  16. S

    Hydrostatic pressure on a teapot spout

    Homework Statement First of all I apologize, the question is originally in my mother language, so I will do my best to translate it. I apologize if I commit any mistakes, and feel free to tell me if something is unclear. The phenomenom where water flows on the outside side of a teapot...
  17. A

    Building a hydrostatic pressure chamber

    Hello! I am currently looking into building a small hydrostatic pressure chamber to test the behaviour of a piece of tissue (cartilage) under physiological pressures. The pressure range should be between 5-15 MPa. I need to measure the volume change/deformation of the tissue, so the...
  18. J

    Find the hydrostatic pressure on the bottom of the aquarium in lb/ft^2

    Homework Statement An aquarium 5 ft long, 1 ft wide, and 5 ft deep is full of water. (Recall that the weight density of water is 62.5 lb/ft3.) (a)Find the hydrostatic pressure on the bottom of the aquarium in lb/ft^2 Homework Equations hydrostatic pressure = ρgd = δd ρ = 62.5...
  19. A

    Hydrostatic Pressure Force must be perpendicular

    Hydrostatic Pressure Force "must" be perpendicular Hi, I'm taking AP Physics B and we started learning about fluids and pressure. My teacher told me that the pressure of a fluid acting in a a container only applies a perpendicular force to the sides, which doesn't make sense. If you 'zoomed...
  20. M

    How can hydrostatic pressure be zero?

    I was reading a paper and I saw a statement that says zero hydrostatic pressure. I was wondering what it means..
  21. B

    Abaqus: Fluid Cavity - Moving cavity under uniform hydrostatic pressure

    Hi Dear All, Hope I can have some suggestions to tackle this weird problem. I have an axisymmetric ball, with CAX8R elements being inflated with hydrostatic fluid elements. Fluid elements surface is put on the internal surface of the ball (defined by picking the surface of the CAX8R...
  22. S

    Is Standard Glass Strong Enough to Hold Back Water in a Bubble Panel?

    hi, i know hydrostatic pressure has been discussed on this forum but I'm still not convinced (i know, crazy me) i have a practical application actually. i'm planning to build a bubble panel (a.k.a bubble wall). its like a tall, wide but very narrow fish tank but no fish, just bubbles. i'd...
  23. JJBladester

    Hydrostatic pressure in the Bernoulli Equation

    Homework Statement The hydrostatic pressure term in the Bernoulli equation (ρgz) decreases with fluid depth. Why? Homework Equations Bernoulli Equation (multiplied by density ρ to give us pressure units): P+\rho\frac{V^2}{2}+\rho gz=constant The Attempt at a Solution In the hydrostatics...
  24. J

    Hydrostatic Pressure on Sponge

    Hi there, I was wondering if the hydrostatic force applied on the surface of a sponge is the same of the same force applied on a different material with the same surface area. Let's say I have 1m^3 of water soaked sponge and 1m^3 of rubber. The forces applied on the surface of those...
  25. E

    Hydrostatic Pressure - Theoretical Scenario

    I have come to understand the basics of Pascal's Principle/Hydrostatic pressure, but there is one scenario I am looking for help with. If I have a piston at the bottom of a chamber of water, and I want to push the piston up to lift the water, I understand that I need to exert a greater PSI on...
  26. A

    Understanding Hydrostatic Pressure: Comparing Green and Orange Axis

    We are interested in pressure along green axis in the first picture and along orange axis in the second picture. Air pressure is constant everywhere. For the first case: under water surface: p = patm + ro.g.h patm = 105 Pa = 105 kg.m-1.s-2 ro = 103 kg.m-3 g = 10 m.s-2 h =...
  27. M

    Resultant Force Due to Hydrostatic Pressure

    I've got a question concerning the resultant force due to hydrostatic pressure. I understand how to calculate an object with uniform dimensions as depth (and pressure) increase. But I got thrown a serious curve ball on a Statics test. The situation was such: A downward facing isosceles...
  28. B

    Hydrostatic Pressure: Submarine Crew Escape Force Needed

    Homework Statement In a submarine, at a specific time, her bottom part is at 30m below surface. Submarine gets a part fail. If the crew would like to get out, they would have to push the door of area 0,75 m^2. Door is at the bottom of the submarine and has weight of 300 N. If you have a...
  29. F

    Thermodynamics Hydrostatic Pressure as Function of Height Question

    How is hydrostatic pressure not a function of the shape of the container? My professor says that the pressure P2 is the same for the figures on the right and left. How does the area of the two sections not matter at all? Clearly, if a plate is inserted of negligible mass, thickness, and...
  30. C

    Deriving Pressure on a Fluid Surface at Rest with Constant Density

    Homework Statement Consider a stationary fluid (u=0) with constant density and take F= (0,0,-g). Find P(z) which satisfies P=P_a on z=h_0 , where z is measured positive upwards. What is the pressure on z=0? Homework Equations Euler's equation: \frac{Du}{Dt}=-\frac{1}{\rho}\nabla P...
  31. C

    Why Does Volume Not Affect Hydrostatic Pressure? | Dave

    One of the six conditions of hydrostatic pressure is said to be that the volume of the liquid does not affect the hydrostatic pressure. Can anyone explain why? Thanks Dave
  32. S

    How can hydrostatic pressure drop to zero?

    Hello everyone, If this is a vessel the hydrostatic pressure would drop along the vessel due to resistance. My question is why does hydrostatic pressure drop if hydrostatic pressure is due to gravity. Gravity is always there, even if the molecules lose hydrostatic energy, they would gain it...
  33. P

    How Does Atmospheric Pressure Affect Hydrostatic Calculations in Tank Design?

    Dear guys, I got a common doubt regarding the pressure at the bottom of a open tank filled with water. 1) Assume a tank of 2m height, filled with water. So the hydrostatic pressure at the bottom of the tank will be 0.2 bar(rho*g*h). Wondering! it is less then atmospheric pressure(1 bar)...
  34. D

    Hydrostatic pressure, and force

    if i am asked to find the hydrostatic pressure on a certain object emerged in a liquid, am i meant to use the barometric or manometric pressure? when asked for hydrostatic force, should i find the force on the object , or the force that the solution applies to the object??
  35. R

    Hydrostatic pressure on triangular plate

    Homework Statement A triangle with base 3 m and height 4 m is submerged vertically in water so that the tip is even with the surface. Express the hydrostatic force against one side of the plate as an integral and evaluate it. Homework Equations \int_{a}^{b}{\rho}g(x)w(x)dx The Attempt at...
  36. 3

    Hydrostatic Pressure and Force

    Homework Statement An aquarium 5ft long, 2 ft wide, and 3 ft deep is full of water. Find the hydrostatic pressure and the hydrostatic force on the bottom of the tank. Homework Equations P=g*\rho*h F=m*g=g*\rho*A*h \rho=62.5 \frac{lbs}{ft^3} g=32 \frac{ft}{s^2} The Attempt...
  37. S

    Automobile Hydrostatic Pressure

    Homework Statement 1) A typical automobile tire has a gauge pressure of around 30 Ib/in^2. How much is that in pascals? If a car weighs 8897N(=2000lb), how much area(SI units) on each tire is in contact with the road? 2) A swimming pool 5m wide by 10m long is filled to a depth of 3m...
  38. G

    Hydrostatic pressure in a submerged pipe

    What would be the hydrostatic pressure near the top of a vertical pipe closed at the top and open on the bottom? Would you calculate the pressure density*gravity*depth measuring depth from the top of the pipe or from its opening at the bottom or the difference between the point of measurement...
  39. D

    Help needed: Hydrostatic pressure forces and torque

    Homework Statement Consider the dam in example 3. Suppose there is a rectangular gate near the top of the dam that can be used to release water. The gate is 4 m wide and 3 m tall and is hinged at its top edge so that it will close under its own weight. Determine the torque on the gate for...
  40. D

    Hydrostatic pressure forces and torque

    Homework Statement Consider the dam in example 3. Suppose there is a rectangular gate near the top of the dam that can be used to release water. The gate is 4 m wide and 3 m tall and is hinged at its top edge so that it will close under its own weight. Determine the torque on the gate for...
  41. S

    Hydrostatic Pressure Explained: Why Does Water Flow & Stop?

    I don't understand. If there is a bucket of water and you put a tube inside the bucket and blow at one end and then release water flows out of the tube. Why does this happen. Also when you raise this tube water stops. Why? This is not homework or anything. :smile:
  42. A

    Hydrostatic Pressure: Calculate Force on Cylindrical Tank

    Homework Statement A cylindrical tank, with base radius 9.4 meter, lies on its side and is partially filled with a liquid whose density is \sigma=1260 kilograms per cubic meter. The liquid fills the tank to a maximum depth of 14 meters. Determine the amount of force (in Newtons) exerted on a...
  43. M

    Hydrostatic Pressure: Liquids or Air?

    Is the equation for hydrostatic pressure limited to liquids? Or can it be used for air pressure as well?
  44. B

    Conceptual Question- Hydrostatic Pressure

    b]1. Homework Statement [/b] In the figure, is pressure at A larger than, smaller than, or equal to the pressure at B? [ Homework Equations The Attempt at a Solution My first instinct is that they are equal because they are at equal heights, but then again, isn't the pressure at...
  45. T

    How Do You Calculate Hydrostatic Pressure in a Spherical Water Tank?

    I have this homework problem and I can't figure it out: All I can figure out is the volume of the sphere =/ Help?
  46. B

    Does Hydrostatic Pressure Follow the Same Rules for All Shapes of Containers?

    My understanding is that the pressure below the surface of water is pgh. p - density of water, g - accel of gravity, h - dist below surface And that this relationship holds regardless of the shape of the container of water. (also, I'm neglecting the atmospheric pressure at the surface)...
  47. G

    Calculating Hydrostatic Pressure Difference

    Hi I am to calculate the hydrostatic pressure difference - given by the \Delta P = n*f/A where f = 0.4 kcal/mol/Å. The unit cell has the dimension 23Å x 19.9Å x 30.4 Å and the number of water molecules are 5.4 Å in the z-direction with a molar volume of 55.5 mol/l. I start by...
  48. D

    Explaining the Hydrostatic Pressure Paradox: What's Wrong with the Flask?

    Hi! I came over this paradox: an Erlenmeyer flask and a beaker are filled with water to the same height - it is assumed that they have the same base area and the same mass. Then the hydrostatic pressure of water is the same at the bottom of each container (since the depths are the same) and when...
  49. mbrmbrg

    Hydrostatic pressure (basic basic stuff)

    hydrostatic pressure (basic, basic stuff) Homework Statement In Figure 14-31 (attatched), an open tube of length L = 1.8 m and cross-sectional area A = 4.6 cm2 is fixed to the top of a cylindrical barrel of diameter D = 1.2 m and height H = 1.8 m. The barrel and tube are filled with water...
  50. C

    How Do You Calculate Hydrostatic Forces in an Aquarium?

    An aquarium 5 ft long, 2 ft wide, and 3 ft deep is full of water. Find (a) the hydrostatic pressure on the bottom of the aquarium, (b) the hydrostatic force on the bottom, and (c) the hydrostatic force on one end of the aquarium. For (a) the hydrostatic pressure is P = \rho gd which is 187.5...
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