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Questions tagged [fluid-statics]

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Mercury Barometer

Why Mercury surface is flat instead of convex at 760mm Hg level in Mercury Barometer? refer the image attached. note that At top it is a vacuum and surface tension = (pi-po)r/2.
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1answer
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What makes an ideal liquid- incompressible?

Just thinking about liquid and Pascal's law when, this question came. Ideal liquid, I understand, are deemed to be incompressible, which simplifies our problems while decently holding good for some ...
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Normal Stress differece

What is the purpose of normal stress difference (t11-t22=N1) in uniaxial elongation and simple shear flow? what this different tell us about ?
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Fast reversible switching from hydrophobic(>120 degrees) to hydrophilic (<60 degrees)?

I found few papers on reversible switching from hydrophobic to hydrophilic Reversible Hydrophobic to Hydrophilic Transition in Graphene via Water Splitting Induced by UV Irradiation Light-induced ...
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Confusion about the coefficient of surface tension and the relation between force and length of a body

I haven't found a software that can create 3d or 2d shapes filled with liquids so I posted this picture. I know that the p=2σ/r where p is the pressure that goes inside the liquid and I guess that σ ...
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Density of different liquids in manometer

According to diagram, liquid X and liquid Y have the same pressure on mercury, but how can I know which of them will be denser, liquid X is denser than liquid Y or reverse argument?
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Is this working by communicating vessels?

https://www.youtube.com/watch?v=JzuamK0AyC4 I think the first 2 bottles are working by communicating vessels because i think that the third bottle is with atmospheric pressure and since the second ...
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Unit of Mass density or density of a liquid substance [on hold]

can any one tell me what is wrong with this Question. my practice test series has many question related to the mass density but all give me ANS (c) in options but according to me answer should be (a). ...
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1answer
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Diameter to prevent water flow into a closed-end tube?

Imagine I drill three holes of different diameter into a large block of plastic but the holes don't go all the way through. (They form three close-ended tubes, see the image.) I then submerge the ...
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4answers
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Does a non-buoyant (denser than water) object (such as a lead diving weight) weigh any less when submerged in water?

I've just been discussing this question with my eldest son, who is an extremely intelligent man, as well as being an engineer, a sailor and a scuba-diver, and he believes that an object heavier than ...
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1answer
29 views

Block completely immersed inside the fluid

Consider a block with density $\sigma$ kept in liquid of density $\rho$, where $ \rho > \sigma$. Now what is the cause of force by which it moves upwards? Is it buoyant force? If yes, then how? As ...
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Bubbles in a Pipeline 2

This question has kind of been asked before here, but aren't the gas bubbles in the pipeline also a moving fluid and so as they get constricted shouldn't their pressure decrease too. If so how are ...
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What is the pressure of water after entering atmosphere? [closed]

I was wondering if water exits from the pump and reach the ground, is the pressure of the water at the point of the ground be 0?
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1answer
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Atmospheric pressure in a closed container

it's my first post here but I just have a quick question regarding my fluid mechanics assignment. There's an inverted manometer setup like in the photo which is a closed system. It's given me ...
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3answers
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Will buoyancy act on B? [duplicate]

A is immersed in water, buoyancy must act on A; B is at the bottom of the container, there is no water between B and the container, that is to say, the bottom of B is not in contact with water, so ...
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1answer
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Hydrostatic pressure to measure water level

I am measuring water level in a 25-inch tall vase using hydrostatic pressure. Like this. To do this I have a 1/4 OD inch nylon tube connected to a gauge pressure transducer. So far it has been very ...
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1answer
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Will a piece of ice, floating on water in a beaker, rise or fall when I add oil on top of water? [duplicate]

There is a beaker of water with ice floating on top of it. If I add oil (lighter than water and ice) to it such that it forms a layer above water and ice is suspended between those layers. Does the ...
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forces in free liquid surfaces

why the answer does not take into account the area of ​​the sides of the triangle?(F=PA) the vectors on the right side of the triangle what do they indicate? the pressure is not even a vector the ...
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Easy derivation of Pascal's Law

I would like to know a simple derivation of Pascal's Law, i.e. why the variation of pressure at a given point of an incompressible fluid also happens to all others.
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Size of a raindrop

Thinking about the fact that raindrops come with a typical size I was wondering how this can be determined. I am pretty sure that the friction with air and the quantity of water in the clouds are ...
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1answer
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How does surface tension cause glass plates to attract?

I am having trouble with this example : As it says that the contact angle of the glass water interface is $0^{\circ}$ , so the force due to surface tension should act downward on the plates (rather ...
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1answer
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Effect of increased air pressure on water pressure in sealed container

Imagine I have a plastic bottle filled most of the way with water and with a bicycle pump attached to the top without any leaks... If I increased the air pressure in the top of the bottle to, say, 30 ...
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1answer
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Contact angle of a thin film problem

I am having a hard time with problem 8 , so can anyone give me some hints. I'll say the things I have in mind I can use the Laplace pressure difference equation to find the the excess inside pressure....
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1answer
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Can a pressure wave induce pressure in a liquid it's propagating through?

I have a piece of cylindrical plastic container containing a liquid and sealed at all ends. The bottom seal is a flexible material that can be broken with enough force. The question is then is: can I ...
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Hydrostatic pressure

The solvent in which porous structure will create higher hydrostatic pressure at the beginning of the solvent removal process? I have two porous cakes, A and B with different height. A is 9.6 cm and B ...
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1answer
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Height of fluid and pressure

It’s a well known fact that pressure at bottom of the contain depends on height of the fluid column above it. If I add a ultra thin capillary tube as a fifth tube, then height of the water column ...
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5answers
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Does Archimedes principle account for depth?

The principle states that the upthrust acting on an object is equal to the weight of the fluid displaced by the object. However, this to me suggests that no matter how deep an object is immersed in ...
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How does Bullheading work?

Bullheading, a method of Well Kill, involves simply pumping the kill fluid (heavy fluid) directly down the well bore forcing the well bore fluids back into the reservoir, does the heavier fluid flip ...
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Does tilting a liquid develop shear stress on its surfaces?

Please help me these confusions I have. If I tilt a cuboidal container containing an ideal fluid (non viscous liquid), does a shear stress develop on the liquid due to some shearing force acting ...
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Does angle of contact remain constant for rise of liquid in a tube of insufficient length?

My book states that for rise of liquid in a capillary tube of insufficient length h * R (radius of curvature) = constant. Since the tube is of insufficient height radius of curvature increases to ...
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1answer
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Force on the base of a container

There are 3 containers ,having the same base area ,having being filled with the liquid of same density to the same volume as shown in the figure. What will be the force exerted on the base in each ...
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5answers
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If atmospheric pressure is 76 cm of $\text{Hg}$ , why won't 76 cm of mercury stay in an open tube when suspended in air?

If we keep an hold a tube in air with the closed end up and open end downwards, containing mercury upto a length of 76 cm, why does the mercury not stay in place? Shouldn't atmospheric pressure exert ...
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1answer
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What is the minimum amount of matter do I need to call it “bulk” matter?

I had been reading about bulk properties, but was confused what should the minimum amount of matter be for these properties to hold. For eg: Intensive thermodynamic variables will not remain ...
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1answer
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Normal force on a fluid container [closed]

I was solving some problems and came across the following situation. Consider a container with one cylinder on top of the other. Area of cross section is $2A$ and $A$ for the bottom and top cylinder ...
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Hydrostatic forces of water spilling over gravity wall with slant sides

I want to calculate the horizontal and vertical components of hydrostatic forces on section of the dam. I understand that the force of water on the upstream surface is the same as when the side is ...
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2answers
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Buoyancy question

Suppose we have a ball of volume V and a block of the same volume V whith same density. We submerge the ball into some kind of liquid so that $\frac{1}{2}V$ is submerged into the liquid. We do the ...
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5answers
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Why can water be sprayed farther when the pipe outlet is narrowed?

Someone told me: This is because the flow rate remains unchanged, so the flow rate of small diameter pipelines is faster. I don't think this explanation is right: the diameter of the pipe outlet is ...
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2answers
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Which way does the fluid flow? [closed]

In the given siphon arrangement if a hole is made at D, will water leak out or will air leak in? I think air should leak in as fluids flow from high to low pressure but I'm not sure... Any help ...
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1answer
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Buoyant force when object is between two liquids

Suppose we have a ball floating in liquid A. Then we pour a liquid B on top of the ball (Assuming that the liquid is poured such that the ball doesn't oscillate) . The ball rises up. Why? According ...
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2answers
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Does capillary rise violate hydrostatic paradox?

If $p$ is a pressure and $p_A = p_{\text{atm}} + hdg,\,$ $p_B = p_{\text{atm}}$, is hydrostatic paradox violated, shouldn't $p_A=p_B$?
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2answers
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Bernoulli equation: how should one imagine $\frac{p}{\rho}$?

The Bernoulli equation states the following $$ \frac{1}{2}u^2 + \frac{p}{\rho}+ gz = \text{constant along a streamline} $$ where: $u$ is the fluid flow speed at a point on a streamline, $g$ is ...
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3answers
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What is the physical origin of buoyancy?

Imagine a horizontal cross-section $\Delta S$ of a cylinder containing a liquid of density $\rho$. The downward pressure on $\Delta S$ at the depth $d$ from the surface of the liquid is $P_{down}=\rho ...
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1answer
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Horizontal force on a fluid surface

I was doing some problems involving calculating the thrust due to pressure on curved surfaces. One way, of course, was to integrate over the surface to find the thrust. I noticed that the answer ...
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3answers
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Fluid mechanics - pressure [closed]

We know that pressure inside a container depends on depth. My question is that if this true then if I fill water in a one end closed pipe which has diameter of 2cm and height is 4m and if I fill the ...
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Why does P = $\rho$gh seem to contradict equal accelerations of fluids in a closed U tube?

This is based on a problem. The closed U tube is as shown : I want to figure out time period of small oscillations if the liquid interface is slightly disturbed. My take : considering an ...
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2answers
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Hydrostatic Paradox - weighing issue

In the picture below, both tubes have the same pressure at the bottom. I understand that if they were weighed individually, they would show a different result since the water on the second tube is ...
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1answer
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How to calculate the specific weight of air?

First of all sorry for my bad English ... I have to calculate the specific weight of air knowing that in the air there is actually a small percentage of water vapor. Therefore the specific weight of ...
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1answer
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Is there a relation between the pressure at a point in a fluid and the pressure on the surface of a horizontal object placed at the same point? [duplicate]

So if the pressure in a large fish tank 10 meters below water surface is 50 Glitches (didn't have a realistic number so I put an unrealistic unit), and a Pancake batfish stands still there for a while,...
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1answer
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Drinking Straw physics [duplicate]

I was just wondering, when you put a straw in water and block the top, water doesn't get out from the bottom when you lift it up. What about alcohol like Vodka ( ethanol )? I am trying to make a ...
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1answer
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Forces in a hydraulic lift

My answer states that the force applied is the same for 1 and 3 but less than the one in 2. I understand why 2 is greater than 1 but do not understand why 1 and 3 are the same when 3 has double the ...