Force per unit area.

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Thermofluid mechanics inclined plane

As shown in the attacked image, a tank has an inclined wall at an angle of 450 to the horizontal. On this wall, there is a 1m square door that is hinged at A and has a simple latch at B. The distance ...
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1answer
17 views
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5 views

What liquid has the lowest known solubility of O2 at 20°C, 1 atm?

I have recently started a project on hydropneumatic devices, i.e. devices that use hydraulic fluids in conjunction with high pressure gases. In such systems, the most immediate thing you would want ...
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0answers
21 views

What are the calculations specifically needed for High Altitude Ballooning? [on hold]

I want to know the lifting gas needed to launch the vehicle including the positive lift I want to predict the possible retrieval site I want to know the burst altitude AND MAYBE ALL WITHOUT ...
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3answers
79 views

Physical explanation of Pascal’s Law

I have a problem with physical explanation of Pascal’s Law. For example, when I was teaching my sister (a high school student) about force transmitting by a rope, I said her: “In a very simplified ...
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1answer
30 views

Atmospheric pressure question [on hold]

I'm asked to find at what altitude atmospheric pressure falls to 10% of the mean sea level value. I have found the expression for the variation of pressure with altitude to be $$p = p_0e^{-h \over ...
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27 views

Would it be possible to kill a flea or mosquito with a high probability using high pressure and low volume? [on hold]

I was thinking about how to kill off some bugs in the house and it dawned on me that part of the ritual of spraying down insects is the spray itself - they don't seem to handle the pressure well, and ...
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0answers
18 views

How heated air moves [on hold]

Ok so how does air move when heated up inside a tube or cone? I am working on a wood stove and curious on how I can get air to flow faster or easier into the burn chambers to fuel the wood. Heat ...
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0answers
19 views

Approximating the pressure drop for a centrifugal fan/blower

Is it possible to approximate the pressure drop for a centrifugal fan by using the fan's characteristics, the airflow, and the speed at which the fluid is being ejected? Would it be possible to adapt ...
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0answers
15 views

Rankine Cycle Reheat Mass Flow Rate

Having worked through many examples on the rankine cycle both non-reheat and reheat, i just have one question. Can the mass flow rate of steam be calculated given only the data below? Boiler ...
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1answer
23 views

If an unsealed water bottle has three holes at a different heights, why would the lower hole give out the most water? Is it because of air pressure?

If an unsealed water bottle has three holes at a different heights, why would the lower hole give out the most water? Is it because of air pressure? I am guessing it's because air pressure pushed on ...
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3answers
39 views

Do you need to increase pressure to pump a fluid from a large pipe through a small pipe?

The application of this question is towards clogged arteries and blood flow. I am wondering why people with clogged arteries have high blood pressure if a smaller artery (assuming it is smooth and ...
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1answer
27 views

Thermofluid mechanics, calculating load on a steel water tank

An open cylindrical water tank 2.4m diameter rests on three legs evenly positioned around the periphery of its circular base. The base and sides of the tank are made from steel with relative density ...
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19 views

rising temperatur in compressed solids

I'd like to understand why a solid body is heating up (rising Tempertur) when submitted to external pressure. The pressure will only change the volume minimally, how are the lattice molecules caused ...
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2answers
50 views

Submerged water jet

I am trying to calculate at what pressure and speed water from a high pressure water jet will hit an object 100 millimeters away from the nozzle opening, but i can't figure it out. The nozzle will ...
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2answers
48 views

Atmospheric pressure changes on plastic bottle containing a liquid

We have a problem at work and I need some help on a theory. We ship a liquid in plastic bottles using a pump closure. Recently some of the bottles have been arriving to customers having leaked. The ...
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0answers
39 views

Bernoulli principle and falling object

Consider the following situation, also depicted in the picture bellow (and please excuse my lack of Paint skills): A helicopter is flying at a constante altitude, and hovering the same ground spot. ...
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0answers
35 views

Why does the lack of pressure in outer space affect what's inside our bodies?

I have read multiple similar questions on this site, but none answer specifically the thing I am having trouble understanding. I have read repeatedly that a lack of pressure will cause the fluids ...
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0answers
11 views

Rarefaction/compression events detection using time resolved sound measurement

I had a question about sound measurement in air using a B&K condenser microphone. In the acquired time resolved sound measurement signal I can see both negative and positive voltages/ pressure ...
3
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0answers
40 views

Air preasure vs temperature [closed]

Suppose you have a container of 1 liter of air at sea level with an initial pressure of 1 atmosphere. How high could the pressure get by only raising the temperature. Is there a point (providing the ...
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0answers
22 views

Refrigeration copper tubing

Recently I have seen few kinks and dents in the copper tubing refrigeration line of my air conditioner.Could anyone give a possible reason for this.
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1answer
19 views

Phase diagrams and critical pressure

If a solid substance is pressurized past its critical pressure, what happens? Is the critical pressure only a factor when a substance is over the critical temperature also? On another note what makes ...
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2answers
34 views

Why does an ideal gas not consist of identical molecules? [closed]

since the mass , temperature , and number of particles are the same , shouldn't the molecules be the same so that the pressure of the gad is inversely proportional to the volume.
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23 views

effect of opening the barrier between a tube with one side pressurized and the other side a vacuum

What would happen when a tube with an air space pressurized to 500 atm by the water exerted at 5 km below the surface was opened into a vacuum chamber rising up 5 km to the surface? The bottom of the ...
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1answer
68 views

Statistical Physics: How do we derive this equation?

I'm reading through Statistical Physics by F. Mandl and there is a step in arriving at an equation that I don't follow. He uses $$P = \sum_r p_r \left(-\frac{\mathrm dE_r}{\mathrm dV} \right) ...
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1answer
32 views

Surface tension in a balloon wtih water [duplicate]

Imagine such situation: We have an empty balloon. We put a long, narrow tube into this balloon and we fill it with water. Then, the volume (and surface) of the balloon will start to increase. The ...
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1answer
23 views

Bulk modulus of supercrtical air

For gaseous state air has bulk modulus of ~pressure, but what about bulk modulus values about the supercritical pressure treshold, are these still pretty much same as the pressure or does this ...
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1answer
32 views

What is the difference between pressure in water droplet and that in an air bubble?

The question is at least supposed to be simple but yeah, I need some detailed answers. I have tried thinking about it in the lines of surface tension but it seems what is required of me is more than ...
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0answers
15 views

In a flowing fluid, why the particles are gathering together under critic distance and separating above this distance?

In a flowing fluid has an inner pressure which gives it some abilities. So this fluid is flowing from narrow gates, the speed of flow is increasing while the pressure of fluid is decreasing. If we ...
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0answers
8 views

Does the rate of pressure change matter when measuring the strength of a closed container?

If I had a container that could hold 100 psi, and I increased the pressure to 100 psi instantly would I cause any excess stress on the container, or would it not make a difference from doing it over ...
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20 views

pressure inside a fluid

If we have a fluid in a container at a specific pressure, is the pressure in every point inside that fluid the same and equal to the pressure of the fluid in the walls of the container?
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3answers
52 views

Pressure or confusion

We all know that pressure is force per unit area. for example we have a pressure of $5N/m^2$, so is the load of $5 N$ acts on the entire area or it acts just at a point i.e. is the load a point load ...
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0answers
22 views

Pressure in a balloon as a function of its diameter [duplicate]

Premise #1: Balloon is a perfect sphere Premise #2: We add water in order to increase the diameter of the balloon Is there an equation allowing us to find the pressure in the balloon, as the diameter ...
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1answer
62 views

Static fluid pressure does *not* depend on the shape, mass, or surface area of the liquid. Huh?

I came across this figure that I'm currently unable to accept. I've come up with a thought experiment. Please point out my error: Assume zero atmospheric pressure and no boundary effects of the ...
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1answer
21 views

How many PSI is required to evacuate water from a tube?

I am building a boat lift which has five flotation tubes (8' long, 36" wide and 40" deep) that has a 4" hole on the bottom of the tube. On the top of the tube is a 1" hose that connects to an air ...
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1answer
47 views

What height is atmospheric pressure half that at sea level?

$PV = NT$, where T is a constant $P = \rho g h$ but I don't think this equation can hold in this form as the density is most definitely not constant as we go up in the atmosphere $\rho = ...
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1answer
40 views

Related to pressure and force [closed]

If we made a thing like the one shown in the figure where the cross sectional areas of two piston heads are different and exposed to the same atmospheric pressure and the air between the piston heads ...
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2answers
22 views

Pressure question problem in forming the equation

A tank contains sea water of density $1030 \frac{kg}{m^3}$ The pressure at point M is $60 kPa$ more than atmospheric pressure. Calculate the depth of M below the surface of the water. My attempt: ...
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0answers
18 views

How does air density affect corona discharge?

I'm wondering how local air pressure and density affect the amount of ionizations occurring in a corona discharge. Also, does the threshold voltage required for a corona discharge vary with air ...
2
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0answers
22 views

Pressure on a piston [closed]

There are 2 syringes X and Y connected to each other horizontally. If pressure in atmosphere (P) is 1x105 Nm-2 and the pressure we should apply on X to have the velocity when liquid come out is ...
1
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1answer
27 views

Forces & Pressure

So, today I learnt that P=F/A. For something with a flat surface, it is easy to grab. Then came to my mind, how about the pressure exerted by a curved surface? How do you calculate the pressure? To ...
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1answer
35 views

Gas/liquid pressure equilibrium of water in an exotic environments

So I'll preface this by saying this is not some evil homework assignment, this came about from some idle talk of colonizing the moon by a couple of software engineers when we realized we had no idea ...
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3answers
83 views

How is pressure kept constant in Charles' Law?

Generally, a piston is kept on top of a cylinder containing the gas. The gas is heated and it expands causing a change in the volume. I was wondering how might one keep the pressure constant. Websites ...
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2answers
55 views

velocity of water exiting a 20 m hole at the bottom of water column 5000 m in height

What would be the velocity of water exiting a tube that has a height of 5000 m from a hole with a diameter of 20 m at the bottom, if the height of the water remains constant at 5000 m? Would it be ...
1
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1answer
31 views

Nonzero stress on crystal at equilibrium volume?

Using a first principles computational method such as DFT, you can calculate the energy of a unit cell at different volumes to obtain a parabolic energy vs. volume curve. The minimum of this curve ...
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1answer
29 views

Explanation for concept of Relative Density

I am in class $9^{th}$, I'm reading my physics book in which it is written that: $$\mathrm{Relative\ Density} = \frac{\mathrm{Weight\ of\ solid\ in\ air}}{\mathrm{Loss\ of\ weight\ of\ solid\ in\ ...
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1answer
44 views

Why blasts/explosions hurt people

This seems a stupid question i know but can't really understand the physics behind it. Let's imagine i'm 5 meters away from a bomb and it explodes. Putting apart the high speed projectiles behaving as ...
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1answer
36 views

Atmospheric pressure below sea level

If I go up in the air the amount of oxygen decrease and the atmospheric pressure gets lower. What would happen if i dig a hole 100 km down? does atmospheric pressure go up? when is the pressure so ...
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0answers
22 views

Noise created due to change in Air Pressure

Background : My blower in one of the experiments is generating noise due the a short airflow path to atmosphere. The reason is due to a sudden change in pressure (high to low) the high noise is ...
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1answer
25 views

Humidification Problem [closed]

Humidification Imagine that water is evaporating into initially dry air in the closed vessel shown schematically in Fig. 8.1-1(a). The vessel is isothermal at 25 C, so the water’s vapor ...