# Questions tagged [fluid-statics]

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### Metallic coin over wooden block in glass of water

So there is some water inside a container; the height of water inside the container is $l$. I placed a wooden block on the water and it's floating to some height $x$, on top of the block is a metallic ...
327 views

### Is it a misconception? [closed]

In our textbook it is said that if buoyant force is W and weight of an object is w then object will float when W > w object will be submerged and it wont float(it will sink) when W < w ...
3k views

### How do we measure pressure above a liquid column?

Consider this point $A$, just at the surface of any liquid exposed to atmosphere. The hydrostatic pressure exerted by this liquid of height $h$ is $h\rho g$. My confusion is tha that this pressure ...
3k views

### Calculating pressure under water

Say I were calculating the pressure under 1 foot of water, in psi. I'm thinking the pressure is force per unit area, and should be equal to the force exerted by the column of water standing over 1 ...
1k views

### Why don't forces on two surfaces of a fluid need to balance?

In my textbook (Resnick Halliday Krane), the derivation for pressure in a fluid at a given depth is done assuming that the fluid is homogeneous. Thus, the book concludes that the pressure in a fluid ...
293 views

### The highest density of water

If temperature is decreased, volume decreases. so density increases. But in case of water, its density increases up to 277 K, then decreases. Why does this happen? Why 277 K is water's highest density?...
377 views

### saturated water vapour pressure [closed]

A pressure steel tube has a volume of 215 cc and contains air at 207 bar. It also contains some water (put it is 0.5 cc) deriving from the condensation of air humidity during pumping air into the ...
6k views

### Weight of solid partially immersed in water

Suppose a spherical object is kept in water and nine tenths of the object are inside the water, while the remaining tenth floats. Find the weight of solid inside liquid. By Archimedes' principle, if ...
11k views

### How to calculate the buoyant force on a balloon at different altitudes [duplicate]

For a project into balloon simulation I'd like to know how the force on a balloon changes with altitude: I know that the Buoyant force on a balloon is: $F = (\rho_{air} - \rho_{helium})gV$ Using ...
536 views

### Pressure and Buoyancy [closed]

It is well known that you can trap water in a drinking straw by placing the tip of your finger over the top while the straw is in the water, and then lifting it out. The inner diameter of the straw is ...
13k views

### How to calculate pressure loss due to water leakage from a hole in a pressurized unit

I am trying to develop a method for calculting the rate of pressure loss from a small hole in a pressurized vessel full of water (small air pocket likely at top of vessel). I've found a formula for ...
302 views

### Given a slanted pipe [closed]

Question: I have a pipeline that is tilted. I know the length of the pipeline, and the pressure (90psi) that is felt at the very bottom. I'm trying to find out how much liquid has leaked out if the ...
376 views

### what is the static pressure in a yield stress fluid?

Suppose I have a tank filled and there is no slip at the walls. If the tank is filled with a Newtonian fluid and is in static equilibrium, we know that the pressure is defined as $p = \rho g z$. But ...
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### Does the weight of fluid in a conical container act entirely on the base?

Scenario description Lets assume both containers have a capacity of 300 litres. One is a vertical tube as shown in pic 1 Other one is more or less a V shaped containers as shown in pic 2 Both are ...
516 views

### Gauge pressure clarification

Is gauge pressure always zero-referenced against ambient air pressure? Or is it referenced against the sum of all pressures acting on a fluid, which usually just happens to be ambient air pressure? ...
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### Difference between weight of water and pressure of water

(I didn't even have a basic formal education in physics. I'm learning through the internet out of my own interest, so if there are any silly mistakes, kindly bear with and guide me through.) ...
50 views

### Calculate electricity generation

A friend of mine stays near a water stream and wanted help to use its water. The height up to which the water could be raised using the water flow is 12ft. How much electricity can it produce? Is it ...
359 views

### Why doesn't the air in a Standard Diving Dress crush you?

I recently watched a Mythbusters episode where they tested decompression in a tethered diving suit (which I believe is a Standard Diving Dress). When they removed the air pressure, the suit crumpled ...
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### How does buoyancy work?

I realised, reading another Phys.SE question about balloons moving forwards in an accelerating car that I don't really understand how buoyancy works. Particularly concerning, for a SCUBA diver. The ...
314 views

### How quickly should a fluid come to hydrostatic equilibrium?

Let's say I'm holding a one-liter water bottle, full of water, which I then drop. Before dropping the water bottle, the equilibrium is for there to be a pressure gradient in the water canceling the ...
21k views

### Hydrostatic pressure - doesn't density vary with depth?

Our class is learning about hydrostatic water pressure and we have been told that we can calculate the force of the liquid on an object at any depth using "the density x 9.8 x the depth". However, as ...
2k views

### Calculating Pressure in CGS units

calculate pressure in CGS units using following data :  \mbox{Specific gravity of mercury},\gamma_{Hg}=13.6\\ \mbox{Density of water}, \rho=10^3{\rm kg/m^3}\\ \mbox{Gravity}, g=9.8{\rm m/s^2}\\ \...
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### What is “hydrostatic uplift pressure”?

I was reading Wikipedia about the St. Francis Dam and came across this sentence. Water that collected in the drainage pipes under the dam to relieve the hydrostatic uplift pressure was carried ...
300 views

### Why is the pressure on top of a slab of water greater than the pressure on the bottom?

In the image below, my book seems to be saying that if you have a cup of water in complete equilibrium, then if you have a small cube of water inside the cup given by $dm=ρAdy$ there is a downward ...
1k views

### Hydrostatic pressure at the center of a water planet [duplicate]

If we take an imaginary planet which consists entirely of water (i.e. a big ball of water in space), what would be the pressure at the center of it? My friend argued that it would be zero, since the ...
3k views

### Does gravity cause Archimedes' principle and how?

Why do lighter objects float and denser sink? I understand this from the perspective that if the object can displace the equal mass of water it will float, but I wonder from the perspective of gravity!...