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Questions tagged [fluid-statics]

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2
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0answers
19 views

Why does fluid under pressure not flow into closed-off tube?

While doing an experiment, I saw an interesting situation. The set-up is shown: I plugged the end of the tube with my finger, and slowly started pouring in the liquid. However, as I poured, no liquid ...
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0answers
24 views

Liquid pressure at a certain depth

How do I calculate for the total force at the bottom of a pail, given that it has 20 cm diameter and top 30 cm diameter, it is filled with water to a depth of 18 cm
4
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2answers
51 views

Will the box float?

If you submerse an object in water it will float if its density is less than that of water. This is because pressure increases linearly in water as you go deeper, so the bottom of the object ...
0
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0answers
29 views

Is swimming more difficult under high hydrostatic pressure?

The force required to displace water increases as hydrostatic pressure increases, causing things to be crushed at high depth. Is there a correlation where locomotion and mobility gets more and more ...
0
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1answer
33 views

Kinetic energy for a hydrostatic fluid versus a nonhydrostatic fluid

I am reading in my textbook that the kinetic energy of a non-hydrostatic fluid parcel is given by $\boldsymbol{v}^2/2$, where $\boldsymbol{v}$ is the velocity with components $(u,v,w)$, but for a ...
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0answers
15 views

A problem of Hydrostatic [closed]

I saw the answer of this question but I dont understand please help me
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1answer
25 views

What is the atmospheric pressure inside upside down cup?

If we turn a cup upside down, what is the value of atmospheric pressure inside it and why? Thank you
0
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1answer
73 views

Total force on a ball [closed]

There is a cylindrical container of some radius and some height. A sphere with radius half of the cylinder is stuck in the bottom such that half of it is in cylinder and half outside. Now the cylinder ...
0
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2answers
56 views

Problem Regarding Buoyancy

A spherical marble of radius $1\,$cm is stuck in a circular hole slightly smaller than its own radius (for calculation purposes , both are equal) at the bottom of a filled bucket of height $10\,$cm. ...
1
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1answer
29 views

Pressure at depth $h$ of a spinning bucket at top of swing

This was a question posed to me some time ago and it has haunted me ever since. Hints and suggestions would be awesome. Say someone is spinning a bucket of water in a vertical circle of radius $r$ ...
1
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4answers
61 views

If a toy boat is added to the side of a tank of water that is balanced on a central pivot, why doesn't the tank tip?

Suppose we have the following situation: A toy boat is placed in a tank of water that is perfectly balanced before. Which way, if at all, will the tank tip? As the boat is placed in the water, by ...
2
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1answer
70 views

Knudsen Number and pressure

When computing the Knudsen number to know if the continuum hypothesis can be applied as $\frac{k_B T}{p \sqrt{2} \pi d^2 L}$, do we use the static or total pressure of the free stream? My object is ...
2
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1answer
66 views

Derivation of scaled Richardson number and speed of internal gravity waves for density stratified fluid

My questions relate to page 29 of this document. In particular, on page 29, two expressions for the bulk Richardson number are given; one is said to be 'before scaling'. How is the first expression ...
1
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2answers
46 views

derive the density of water from its molecular structure?

Is it possible to derive the density of water by looking at its molecular structure? Is there a theoretical formula that describe the dependence with temperature? Thanks for the help!
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0answers
21 views

Hydraulic lift and hydrostatic pressure [closed]

If we have a simple hydraulic lift with one piston which we push down (piston A), and the other piston (piston B) which is below the first one, should we include the hydrostatic pressure in our ...
2
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0answers
31 views

Why does dust form islands on top of water? [duplicate]

When you pour sand into water, first the dust particles that are floating on the surface, are separately all over. Then as the water flows, the dust particles should just randomly move around staying ...
1
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1answer
81 views

Which direction a wooden cube would float in water? [closed]

If you place an uniformly dense wooden cube in water, would it float: face up vertex up edge up And why would that be the case?
0
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1answer
41 views

Is Coefficient of viscosity frame dependent? Why/Why not?

Is Coefficient of viscosity frame dependent? Why/Why not?
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0answers
27 views

Perpetual Motion Explanation [duplicate]

Hello could someone explain the reason why this machine does not work. There is an explanation in the text but I cannot seem to follow it. Here is the link - it's the buoyant spheres perpetual motion ...
0
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0answers
16 views

Do the oil and mercury in this manometer affect the pressure in A and B?

One of my friends came to me with this homework question: We've worked out that the height difference between A and B is 50 mm. That makes the difference in pressure between them $$ \Delta P = \rho ...
0
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1answer
26 views

Water pressure distribution up an undersea tube

The following is a screenshot from Sealab 2021, showing a tube erected upright on the ocean floor through which crew can exit and enter the station: This isn't very consistent throughout the show, ...
1
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3answers
42 views

Change of buoyant force as object moves deeper

When reading about Fluid Dynamics, I saw two questions that presented similar situations but had very different answers, and I'm trying to understand why, since they seem contradictory: A beach ...
0
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1answer
8 views

What will be the effects of weight of a fluid containing contain after an external body is submerged in it

Initially taking a beaker containing water of having total mass of water and beaker as W. Now when an external object of weight w' is submerged inside the beaker containing water having density d, ...
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2answers
44 views

Where does the other part of the hydrostatic force go?

The hydrostatic force on the floor is $$F= \gamma \cdot h \cdot Area$$ for both the pipe and funnel. But, for the funnel there is so much more water. So, we expect the force to be higher for the ...
0
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1answer
24 views

Increasing the pressure inside a diving bell

Is it physically possible to increase the pressure inside a water diving bell so that it exceeds the pressure outside it while submerged by allowing water into it?
1
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1answer
28 views

Pressure between interface of two liquids?

Why is the pressure between the interface of two liquids is same?
0
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1answer
35 views

Would a rigid object thats slightly negative buoyant sink all the way to the bottom of a 10,000 ft fresh water lake?

Would a rigid object thats slightly negative buoyant sink all the way to the bottom of a 10,000 ft fresh water lake? I'm going to make a few questions regarding the topic involving a submarine & ...
1
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1answer
27 views

A basic question of positive buoyancy,

Positive buoyancy occurs when an object is lighter than the fluid it displaces. The object will float because the buoyant force is greater than the object's weight. But I also read, buoyancy ...
1
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1answer
18 views

Liquid surface tension and molecular motion inside

In some of the descriptions I have found about surface tension, while they explain the phenomenon for liquid in an open container they use the following arguments: 1) A molecule at the surface feels ...
0
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2answers
30 views

How do I calculate how much weight is needed to sink a specific amount of air and for how deep will it sink? Understanding buoyancy

I'm trying to understand buoyancy so I created a question that should help me greatly. To keep this simple my above is a photo is of a 20 ft long tank. Each line represents 1 cubic ft which each holds ...
0
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1answer
25 views

If a see-saw was filled with fluid and is at an 80 degree angle would the see-saw act exactly the same as if it were completely solid?

I'm trying to understand the 'Lever Principle' and have made up a few questions to help better understand the concept. Although researching the subject I'm having troubles finding any videos or ...
3
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1answer
69 views

Lattice Boltzmann Method: How is shear flow handled in D2Q5?

I've implemented 2-dimensional, incompressible, high-reynolds fluid-flow using the Lattice Boltzmann Method on a D2Q9 lattice. My main goal is just visual plausibility, not quantitative accuracy. The ...
0
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1answer
23 views

“Pascal's Principle” hydraulic lift is (F1) the equilibrium to (F2) or alike to the “See-Saw Principle” is (F1) lifting (F2) past equalibrium?

I've been trying to understand "pascals principle" and thus far have learned a lot thanks to this forum. I have a few more questions regarding the topic so along the way please correct me if I'm wrong....
2
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1answer
86 views

Hydrostatics and Buoyant Force

In the below problem the weight of the rod acts at it's centre (the centre of mass). But how do I know from the buoyant force acts? How do I proceed with the rest of the problem? Here's my attempt to ...
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2answers
20 views

Pressure on a fluid element

We consider an element in a liquid at hydrostatic equilibrium such that continuum is maintained. Now to calculate the forces on it we consider body forces and surface force. Our system is simply a ...
0
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3answers
68 views

Understanding the Hydrostatic Paradox in a tilted tube

I simply do not understand how point P2 can be at the same pressure as point P1. As I understand it, the pressure at those points is due to the column of water directly above the point. Well, in a ...
2
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1answer
62 views

Would 200 lb of water thats 150 ft high lift more than 200 lb due to the weight + the extra pressure of the fluid being so high up?

I'm trying to understand Pascals principle in more detail so I made a drawing with a question to find out a segment of the differences between pressure and weight. As demonstrated in the project "...
1
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2answers
54 views

Would it take an equal amount of lb-force as the total water weight weighing down on the piston to be at equilibrium? Pascals principle

Pascals principle sounds simple, but I'm a bit confused on this. A cylinder that's 24" in diameter by 5 ft in height filled with 117 gallons(980 lb) that's connected to 1" diameter pipe going up ...
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1answer
67 views

How to explain the isotropic nature of pressure?

Shown in figure is a pipe in which a fluid is static. The pressure at A is equal to pressure at B since it is at the same level and pressure is isotropic. The pressure at A could be defined as the ...
0
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2answers
59 views

Why is pressure in a fluid lower where velocity is higher? (Without using Bernoulli's equation)

So, it is said that wherever the velocity of the fluid is lower, the pressure is higher. I don't know see how this is reasonable. Can someone please explain this to me without using Bernoulli's ...
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0answers
10 views

Water propulsion: Use air and rigid form to make waves feasible or not?

I had an idea that if you took a piece of material shaped like corrugated steel and positioned it such that the runs were horizontally oriented, attached it to the back of a water craft to span the ...
0
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1answer
17 views

Variation of pressure of fluid in motion

As we all know that for a static fluid, pressure increases as we go down from its free surface. What about fluid in motion? Suppose I eject a jet of water in the air, parallel to the surface of the ...
0
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3answers
88 views

Why the submarine sinks into the bottom of ocean once it starts to sink?

An inflated ballon will rise yo a definite height once it starts rise where as a submarine will always sink to bootom of ocean once it starts to sink, if no changes are made. How then can a submarine ...
0
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0answers
43 views

Gas pressure in an container that is almost full of liquid when the liquid is pressurized

What happens to the pressure of some gas, air for example, that is in a container almost full of liquid, some hydraulic fluid for example, when the liquid is pressurized? The air is at 0 PSIG at the ...
0
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2answers
100 views

Why the force exerted by a fluid on an object submerged in it is always perpendicular to it's surface? [duplicate]

When an object is immersed in a fluid, say or example water, then the force exerted by the fluid is always perpendicular to the surface. I'm unable to understand why is this so? My books writes :- (...
0
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2answers
62 views

Is it possible to have no pressure gradient in a tank? [duplicate]

If a sealed container that is 20 miles high is filled to a pressure of 50psi gauge pressure, will it have a pressure gradient the same as the Earth or does the fact that it is filled to more than ...
2
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2answers
44 views

Vacuum balloon / airship with balloons as shell segments

What are the problems with the following idea for building a vacuum balloon / airship? The question is targeted at the "making it float" part, ignoring other problems with super-light airships (...
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0answers
66 views

I can't prove the Archimedes' principle in a particular case [duplicate]

If I put the cylinder on the bottom i replace F2 with normal force N. But it will be at most equal to F1 plus the cylinder weigh N=F1+$\rho$gV. So how can it get a bigger boost from the bottom to be ...
2
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2answers
136 views

Ice Melting with a Twist [closed]

The Question There are three ice cubes floating in three different cups of water. In the first cup, the ice cube has a pocket of air inside. In the second cup, the ice cube has a pocket ...
0
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0answers
28 views

Bird Transport Phenomena

in the book " transport phenomena" (Bird) when obtaining the famous equation of hagen poiseuille Bird defines a variable that involves the pressure, but when doing an exercise a term magically ...