Force per unit area.

learn more… | top users | synonyms

1
vote
0answers
82 views

Maximum pressure of a rubber balloon

I've had a question about this topic previously, but the material was inelastic. Forces in a balloon popping? What happens when a material is non-hookian? Say rubber, I've found this pdf on the ...
1
vote
1answer
91 views

gas pressure outside nozzle in vacuum

I'm currently trying to figure out the following in the simplest possible way: Say we have a nozzle in a vacuum environment. A gas of a certain pressure is emitted through the nozzle, which has a ...
0
votes
1answer
82 views

Conclusions From a Junior School Science Experiment

If you stick a tissue to the bottom of a glass and immerse this glass fully (upside down) into a tumbler of water, then this tissue remains dry. Why is this so? / What conclusion would you draw from ...
0
votes
0answers
54 views

absorbing energy from explosion

The other day in physics, we went to visit a workgroup that was developing a wall that would absorb energy from explosions (it was a joint project with the military academy). The first prototype they ...
10
votes
4answers
2k views

Why does my door shut faster when the window is open?

I've noticed that if I shut my door when the window is open in a room, the door will tend to shut faster. If I shut the door when the window is closed with a normal force it will not fully close as if ...
0
votes
2answers
78 views

Simulate free fall in a rotating torus?

Say I have a rotating torus filled with air at 1 atmospheric pressure at sufficient speed (and inclined along the direction of the force of gravity with respect to Earth). If the rotation speed were ...
0
votes
1answer
62 views

What is responsible for cutting an apple: pressure or force?

To cut an apple, do I need more pressure or more force? When we want to destroy the intermolecular bonds, don't we need more force ?
0
votes
1answer
421 views

Accelerated liquid in a U-tube

Consider a U-tube containing some liquid. The two ends of the tube are connected to closed volumes of air with different initial pressures, such that there is some difference in the liquid levels ...
0
votes
0answers
47 views

How does pressurized gas constantly push?

If a gas, such as hydrogen, is pressurized into an air tight container, a force in terms of pascals (or whatever unit you want to use) is exerted, correct? That is what pushes against every surface ...
2
votes
1answer
75 views

Why is pressure always non directional? [duplicate]

While hammering a nail (before it is in the wall) it is pretty evident that the tip of the nail is going to be applying a force directed along th axis of the nail, then why is it said that pressure is ...
0
votes
1answer
109 views

How to calculate fluid(oil / hydrocarbon) loss under pressure

I'm trying to calculate the amount of fluid that would flow through an area dependant on the amount of pressure that there is. I'd also like to know the rate at which it would flow. Essentially I ...
2
votes
1answer
259 views

How far do air particles move when a sound wave passes through them?

How far do air particles move when a sound wave passes through them? I know that they don't actually travel, the question is how far do they oscillate or what is the physical amplitude of the ...
0
votes
0answers
106 views

Pascal's law and hydrostatic forces

We know that Pascal's law states that the pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all direction through out the fluid such that the initial pressure ...
0
votes
1answer
291 views

What is the basic difference between absolute pressure and gauge pressure? [duplicate]

What is the basic difference between absolute pressure and gauge pressure? I have a great confusion regarding these two pressures. Please someone explain it to me
0
votes
1answer
21 views

How can I determine a gas partial pressure knowing the flow?

I have a vacuum chamber with a pressure 10-8 Torr. Then I open an Oxygen valve with a set flow of 2 sccm from a tank with a pressure of 2 bars. The pressure in the chamber decreases to 10-2 Torr. What ...
1
vote
1answer
105 views

Energy conservation at a the end of a hose pipe?

I am trying to figure out the energy balance at the end of a hose pipe with water pouring out. Applying Bernoulli's equation inside the pipe we have three energy terms: Kinetic energy, "pressure" ...
0
votes
1answer
111 views

Does the space between molecules have no pressure?

In any living organism there exists are space between cells filled with interstitial fluid. Loss of this fluid into abnormal areas (3rd spacing) can cause relative to severe hypo-volemia. The fluid ...
10
votes
2answers
162 views

How strong is electron degeneracy pressure?

I'm trying to get some specific numbers for electron degeneracy that I can understand, using a concrete example. Take for example this portion of carbon crystal: Exactly how much energy would be ...
-1
votes
1answer
66 views

Loss of atmosphere to a vacuum

I'm working to craft a space-horror themed RPG a la Dungeons & Dragons and I've run into a situation I can't resolve on my own. At what rate is atmosphere lost to space through various sized ...
0
votes
1answer
266 views

Forces in a balloon popping?

How much difference between internal and external pressure can a balloon withstand? how would the value be calculated? I found an equation: ...
2
votes
1answer
67 views

Air pressure in closed (circular) tube

I have learned that for fluids and gases $P_\text{total}=P_\text{dynamic} + P_\text{static}$. Suppose we have a closed circular tube in a form of ring filled with air under some pressure. In this ...
2
votes
2answers
127 views

Initial pressure of explosion

I would like to know, if given a TNT equivalent of explosive (or its Energy) is it possible to determine what would be the initial pressure that will be the result of that explosion ? To be more ...
0
votes
2answers
259 views

Compression and expansion

Why is it that solids on compression [As in striking a hammer etc.] heat up, but liquids and gases on compression [Pressurizing liquids causes them to freeze or gases to liquify] cool down? Can ...
1
vote
3answers
198 views

pressure in fluid mechanics of incompressible liquid

Most liquids can be approximated to be incompressible, since the Mach-number is much smaller than 1. That means that the density variations are negligible and from the relation between pressure p and ...
28
votes
7answers
4k views

Is it possible to “cook” pasta at room temperature with low enough pressure?

It is known fact, that boiling point of water decreases by decreasing of pressure. So there is a pressure at which water boils at room temperature. Would it be possible to cook e.g. pasta at room ...
4
votes
1answer
110 views

Is it possible for bubbles to exist in vacuum?

In the case of a bubble, the outside pressure is less then the inside pressure. If that is the case can bubbles exist in vacuum? I am not sure but this should be true if vacuum has zero pressure
2
votes
2answers
6k views

Does pressure drop across pipe affect flow rate?

Let's say there is a main pipe containing $100\: \mathrm{m^3/hr}$ a fluid of density $750\: \mathrm{kg/m^3}$ and it's gonna be branched into 2 pipes (Pipe A and Pipe B) of the same diameter. If Pipe A ...
3
votes
1answer
93 views

Pressure difference between 2 side of wings of aircraft

I understand why the pressure is reduced above the wings of aircraft, but when I read books and look for information, it says that the air is compressed below the wings, I do not understand why it is? ...
2
votes
1answer
59 views

Logarithmic intensity formula factor?

In formulae for sound intensity and sound pressure, there is a logarithm part for the logarithmic increase of the quantity we're studying, and also a numerical factor 10 or 20 depending on the ...
5
votes
2answers
1k views

Is negative 20 psi / 1.5 bar possible?

If I understand correctly, negative pressure usually means relative pressure: the difference between inside and outside. If outside is normal (1 bar, 15 psi, 100 kPa etc), how low can the (relative) ...
1
vote
1answer
143 views

How does air escape from a pneumatic tire?

Obviously, it is caused by the difference in pressure between the inside of the tire and its surrounding environment; but how specifically is the air escaping?
2
votes
3answers
179 views

What exactly is “pressure”, and what's its relation to force?

I have looked around, and I will admit that I'm a bit lost on the definitions. Wikipedia's opening reads: Pressure (symbol: P or p) is the ratio of force to the area over which that force is ...
0
votes
0answers
53 views

Linearity of the critical isochore?

When looking at the pressure-temperature diagram along the critical isochore (up to quite high reduced temperatures) a very linear trend can be observed. From a theoretical point of view, is the ...
2
votes
0answers
123 views

Second derivative of vapor pressure from a cubic equation of state

It is quite easy to compute the first derivative of vapor pressure with respect to temperature from a cubic equation of state at least at the critical point since there is a continuity with the ...
-2
votes
1answer
239 views

Force on a submerged triangular plate [closed]

A triangular plate ABC is submerged in water with its plane vertical. The side AB is 4m long and is 6m below the water surface while the vertex C is 2m below the surface. Find the force exerted by ...
1
vote
2answers
98 views

Expression for Atmospheric Pressure with Altitude, including Tidal Forces

Is this simple to obtain? I've tried to modify the constant-gravity model to use the $GM/r^2$ form instead, but my result was shown to be wrong with some testing. Constant Gravity Model You can ...
1
vote
1answer
282 views

Will the “Vacuum Wine Saver” suck the bubbles out of Champagne?

The "Vacuum Wine Saver" comes with the following "warning": Not for sparkling wines Intuitively and naively, I imagine that the bubbles (or the "bubble-potential"—my made-up terminology) will be ...
-1
votes
1answer
302 views

Straw and Water

I drink from a glass of water with a vertical straw. What's the longest straw I can use and still drink water if the ambient pressure is 1 atm? Details and assumptions 1 atm is 101,325 Pa. The ...
0
votes
2answers
665 views

Physics of the inverted bottle dispenser

When you invert a water-bottle in a container, the water rises and then stops at a particular level --- as soon as it touches the hole of the inverted bottle. This will happen no matter how long ...
2
votes
1answer
124 views

Pressure applied to flat plate

I have a question about the pressure placed on a plate of material X, how the force is distributed and what would be the material property that would determine its failure. To simplify things ...
2
votes
0answers
90 views

How Temperature, Pressure and Altitude are related in the atmosphere?

I'm looking for an approximation for the temperature of the atmosphere at any height and pressure. Both altitude and pressure are known variables, I've derived this equation using maxwell's ...
1
vote
1answer
238 views

Is temperature-induced change in the volume of balloons dependent on gas?

Which balloon will have higher relative change in volume, helium balloon immersed in liquid nitrogen or air balloon immersed in liquid nitrogen? Since volume is directly proportional to temperature ...
1
vote
2answers
78 views

How does one interpret the 'per unit area' in numbers like tensile strength?

How does one interpret the numbers when reading data about tensile strength, yield strength, and the likes? Say for example reinforcing bars. Grade 40 Rebars are rated at 70,000 PSI for its ultimate ...
1
vote
1answer
365 views

Hydrostatic pressure?

What what I understand, hydrostatic pressure is the "weight" of the water pushing against objects. But if this is true, why is hydrostatic pressure perpendicular to the surface it acts on instead of ...
7
votes
4answers
1k views

Can air bubbles sink at extreme depths? [duplicate]

I was thinking earlier about air bubbles in water. if you had a bubble of air (say in a balloon) then as you take it down in water the bubble shrinks because of the pressure and because it is ...
3
votes
0answers
49 views

Converting impact speed to pressure magnitude

In explosive safety and stability testing, a drop test is commonly used to determine the sensitivity to impact. In the test, an impactor of known mass is dropped. The initial height varies throughout ...
1
vote
2answers
303 views

The Soda Can and air pressure experiment

Yesterday, I made an experiment. I filled an empty (but contains air) soda can with a little bit of water. Then I turn on fire at the sides of the soda can so that the water starts boiling. Next, I ...
0
votes
1answer
61 views

Determining if a solution will boil

A piston compresses a solution of 40% $HNO_3$ in $H_2O$. If the piston breaks and the pressure is reduced from 12.0 atm to 1.0 atm: a) If the temperature of the solution is 110 degrees C, will the ...
0
votes
1answer
162 views

Simple exercises about U-tubes

I want to solve some exercises involving U-tubes, like You pour two non-mixing fluids with densities that go like 1:2 into a U-tube. The fluid is 5cm higher in one arm than in the other. Where is the ...
0
votes
0answers
114 views

Food kept in a container in my pressure cooker cooks slower

The pressure cooker is heated at the base to cook the food. The pressure cooker releases steam when the force exerted by pressure exceeds the counterweight, at which point the weight rises up allowing ...