# Questions tagged [fluid-statics]

Fluid statics or hydrostatics is the branch of fluid mechanics which deals with the study of fluids at rest and the pressure exerted by it on an immersed object. If your question is about the study of fluids in motion, use the tag "fluid-dynamics" instead.

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### Gravitational potential energy of a water column

If there is a water column of height $h$ from the ground level, then the gravitational potential energy should be $E=mgh/2$, since the height to the center of gravity is $h/2$. Now what I don't quite ...
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### Forces on a fluid contained in a U- tube

I have a U- tube filled with the same fluid (which is incompressible) upto a height h on both sides. This is my initial configuration. If I displace the fluid on one of the sides of the U- tube by a ...
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1 vote
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### Fluid Statics (Physics)

When we directly drop a mass into a container of water, the water level rises. In such cases, does pressure vary due to this height variation, everywhere in the fluid? What cases are to be taken into ...
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### How Does Energy Dissipation Affect Momentum Conservation and Resistance to Flow?

I’m seeking clarification on the relationship between energy dissipation, momentum conservation, and resistance to flow in turbulent fluid dynamics. Specifically: How does the dissipation of kinetic ...
1 vote
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### How the heck do liquids work?

Liquids are denser than gases with similar molecular weight, which seems to indicate a strongly attractive intermolecular force; on the other hand they have a negative Joule-Thomson coefficient which ...
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### Mathmatical function of outline of merging droplets [closed]

I'd like to describe the evolution of the outline of two or more merging droplets confined between two planparallel plates (slides). For simplicity I started thinking of one droplet first. Here, the ...
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### How long does it take to achieve buoyancy in a body of water?

Non-Engineer here. Question: As an example, the Canal du Centre Water Bridge, in Belgium. Is the weight on column C greater than the weight on columns A and E? If no, because of buoyancy, how fast is ...
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### When a submarine blows its ballast and rises, where did the energy for the ascent come from?

Suppose a submarine fills its ballast tanks with water at the surface and in so doing becomes negatively buoyant. It sinks, presumably converting gravitational potential energy into kinetic for the ...
1 vote
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### When it is raining why the rain drops making a bubbles when they touches the water surface?

I've observed that when raindrops fall on the surface of water, they create a semi-spherical shape. Why does this happen, and what is this phenomenon called ?
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### If pressure is caused by the weight of water above you, why is pressure said to act in all direction, not just down?

I don’t think I have worded my question very well. Here’s another try… We are taught that pressure of a fluid increases with depth, usually given the explanation of the increasing weight from the ...
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### Is the low pressure behind a (wetting) fluid meniscus local or global when the meniscus is pinned inside a filled capillary closed at one end?

I have not been able to resolve the following question, that has arisen in my experimental setup, despite extensive research. The many sources indirectly addressing a similar configuration seem ...
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### How does Newton's third law apply to forces between fluids and solid surface?

What is the direction of the force exerted by the fluid on the solid surface and what is the direction of the force exerted by the solid surface on the fluid? If I am not wrong, I think the force ...
1 vote
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### How to understand the use of infinitesimals in physics, more specifically in engineering textbooks?

I'll preface by saying that I've gone through many stackex threads and have not found a satisfying answer that would help me understand this. I am truly sorry in advance for the lengthy post, but if ...
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### Buoyancy basics

I was solving this question and in the solution, they have applied a buoyant force exerted by kerosene. It makes sense by the basic definition of the buoyant force from Archimedes principle. However, ...
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### Are there any substances that exist as supercritical fluids at STP?

If not, why If so, please give some examples. I know that some gases can be made into supercritical fluids by compression alone however I am not aware of any substance that is supercritical at stp
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### Components of the reaction forces against a fluid along the horizontal and vertical axes for slanted walls

I came to know that the reaction force (normal force) exerted by the walls of a vessel against a fluid is normal to the surface area of the vessel, which is the nature of a normal force. Also, at any ...
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### How does Shear Force on a fluid in a vessel reaches an equilibrium if molecules are free to make contact?

In Hydrostatic, if the fluid is a perfect fluid that is non-viscous, it doesn't experience any shear force because if it would experience so it might start flowing so something might be working to ...
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### Pressure at a point around the corner in a conical fask [duplicate]

I have gone through this two very informative links in understanding pressure. Weight of fluid in a conical container act entirely on the base? Pressure is isotropic But in a long conical flask which ...
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### Buoyant force on a stick making an angle theta with the vessel

I was solving this question The answer of the question uses balancing of torques. It uses $L=0.5$m I have problem with the fact that they have used buoyant force $F = \rho V g$. Marking the net ...
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### Pressure inside a bubble/drop of water due to surface tension

I was studying problems in capillary action in fluid mechanics and I have a fundamental doubt. Is the excess pressure inside a bubble/spherical fluid body caused by surface tension, the same all ...
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### If air was the same density as water, but still a gas, could you swim in it?

I'm not talking about normal physics here, as it would be extremely hard to get such a situation to arise, this is more a hypothetical question. If air was the same density as water, while still ...
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### Does the compressibility of a fluid depend on its height?

Does the compressibility of the fluid depend on any external factor, or is it an intrinsic property of the body? Like if I have a column of water, if the height of this column is nanometer or meters ...
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### Understanding Pressure Transmission and Lift Mechanics in a Hydraulic Lift

I'm trying to grasp the principles behind the operation of a hydraulic lift, particularly how pressure changes are transmitted and how they result in lifting actions. I have two specific doubts: ...
1 vote
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I was reading about boats, from what i was reading a qubic meter of air should be able to float a 1 ton boat so as far as i understand the equalibrium point will be if a boat wight is 1 ton - 1 qubic ...
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### Rotating Tank of Charged Liquid

Consider a long rectangular tank of dimensions a×b, where a≫b, that is rotating at a constant angular velocity and filled with an incompressible charged fluid. How would one find an equation ...
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### How Does Hydrostatic Pressure Account for Liquid Layers That Can Mix?

I'm trying to understand how pressure in a homogeneous fluid at a given depth is determined by the weight of the fluid above that point. Specifically, I am confused about how the weight of the liquid ...
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### Why rain drops are spherical while water droplets on a glass surface are flat?

Why are raindrops spherical when falling through the air, but lose their spherical shape when they are on a flat surface?
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### Question about Young-Laplace equation proof

I was studying a proof of the Young-Laplace equation, but I came across a dubt in the very begin. Here the initial part of the proof: Consider an interface separating two immiscible fluids that are ...
1 vote
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### Where exactly is the friction with the pipe walls and the fluid? [duplicate]

Is the friction between the walls of the pipe and the no slip layer? Or is it between the no slip layer and the rest of the fluid above?
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### Are bodies in fluids stressed?

If air applies pressure isotropically in all directions normal and into the object, then does it mean that anything in air is stressed by the air pressure? I know that the pressure is all the same in ...
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### Buoyant force: lead block on top of styrofoam block floating on water, then swap de blocks around

I have a quick question related to the buoyant force. A block of lead is placed on a piece of styrofoam in water. In this case, the water comes up to the top of the styrofoam. If we now turn it over (...
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### What exactly is specific gravity and how is it related to fluid statics?

The question is A cubical block of wood of edge 3cm floats in water. The lower surface of the cube just touches the free end of a vertical spring fixed at the bottom of the pot. Find the maximum ...
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### An object is connected to the end of a spring and is immersed in water. What are the forces acting on the object? [closed]

The actual question is A copper piece of mass 10g is suspended by a vertical spring. The spring elongates 1 cm over it's natural length to keep the piece in equilibrium. A beaker containing water is ...
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### Relationship between density and temperature - How to know the precise temperature at which a bell inside a Galileo Thermometer will sink?

A Galileo Thermometer consists of bells placed inside a tube that's filled with liquid. As the temperature increases, the fluid density decreases. This leads to a decrease in the buoyant force, and ...
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### What would happen to a soap bubble if there were no surface tension?

Suppose you have a soap bubble. Now, suppose that the surface tension in the liquid film that surrounds the bubble disappears instantly. What would happen to the bubble? Also, is it possible to form a ...
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### Why does a bubble created in the body of a liquid pop when it rises to the surface?

Suppose you have a glass of water and you blow bubbles in the water using a straw. The bubbles pop when they rise to the surface of water. Why does this happen? Does the surface tension of water play ...
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### What exactly are cohesive and adhesive forces?

Are cohesive and adhesive forces defined only when at least one of the interacting materials is a fluid?
1 vote
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### Wrinkling on a fluid foundation [closed]

I have this problem in fluid mechanics/elasticity and honestly don't know how to start. A large elastic sheet of bending modulus A overlies a fluid of density $\rho$. Due to external compression, the ...
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### What is the pressure near the end of the siphon tube inside water?

Consider a standard siphon Tube as shown What is the pressure at point O in the figure? A continuous streamline is there from A to O to B to C to D (correct me if I m wrong) Applying Bernoulli’s and ...
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### The reasoning behind the buoyancy force equation [duplicate]

If I drop a block in water, the pressure experienced on the top of the block is the $\rho gh$. That is because a certain amount of water is distributing a force above the block. I don't understand why ...
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### Hydrostatic pressure on the side wall

I understand well that pressure from the liquid acts perpendicularly on the walls of a cylindrical container. This applies to liquids and gases. I am trying to re-understand sth from the university ...
1 vote
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### Does a falling column of fluid exert the same pressure as a static column?

Suppose you have a $5\,\text{m}$ high waterfall. The water will be accelerated downwards by gravity and impart a force, proportional to the cross sectional area of the falling column of water, on the ...
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### Force and massa unit [closed]

why in this question did the question answer only perform the product between area*P to calculate the mass? Question: Answer: Shouldn't the mass be calculated as $m = (P \times A)/g$? Considering ...
1 vote
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### Measurement of pressure using pitot tube

We know that pitot tubes are used in measuring velocity of a fluid or dynamic pressure. Now,in stagnation point which is basically the entrance of the pitot tube,the fluid particles are brought to ...
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### Generated pressure when two water interfaces collide

Background I'm studying a bulk cavitaion problem as described in V. J. Cushing - On the theory of bulk cavitation. In the problem an incident shock wave (from the water $z < 0$) is reflected as a ...
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### Pressure measurement using piezometer

When calculating pressure of a flowing liquid,we know that peizometers are used whose one end is open to the atmosphere and the other end is connected to the fluid via a small hole at which we want to ...
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### Doubt regarding the fact that pressure in a fluid at same horizontal level is same

In the diagram shown, we have taken 2 containers of different heights h and h' where h>h'. These containers are immersed in a bucket filled with the a fluid, say water represented with red color, ...
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### Why doesn't the liquid in a liquid-in-glass thermometer slide down when you turn it upside-down?

This question applies to both mercury and alcohol thermometers. I assume the answers would be similar, but maybe not. My understanding is that the capillary in a liquid-in-glass thermometer consists ...
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