Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [pressure]

Force per unit area.

0
votes
0answers
9 views

What happens to pressure when a liquid turns into a gas in a confined chamber?

I'm doing an experiment requiring immense pressures. Since I do not have access to a pump that can create these pressures I settled on something different... Instead of using a pump I want to utilize ...
0
votes
1answer
21 views

Pressure Difference in a Rotating Fluid Coloumn

This question has intriqued me because two methods are generally employed to derive the shape of the surface(paraboloid) . Both methods give equal numerical answer but differ in which of them P or Q (...
3
votes
2answers
58 views

What do bulk modulus values actually mean?

I am trying to understand what bulk modulus is, but it is quite hard for me to understand it. I get that it is the resistance of material to compression from all directions, but what actually happens ...
0
votes
0answers
14 views

Radiation pressure at a surface which is perfectly refracting

Radiation pressure at perfectly reflecting surface = 2I/c Radiation pressure at perfectly absorbing surface = I/c What will be the radiation pressure at a perfectly refracting surface? Will it be ...
0
votes
1answer
22 views

Determining Gas Constant $R$ from Boyles Law?

I have done an experiment (Boyles Law experiment using Boyles Law Apparatus) in order to determine the value of the gas constant $R$. I have also taken into account the dead space volume in my ...
0
votes
3answers
43 views

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 ...
0
votes
0answers
27 views

What process is it when the polytropic index $n$ is equal to $- \infty$?

From $$Pv^n = \mathrm{constant}$$ When $n = - \infty$ What kind of process is it.... Eg... When $n= \infty$, It is constant volume.... Therefore when $n =- \infty$... What is constant?
0
votes
2answers
37 views
+50

Calculating the power of a pneumatic piston vibrator

I am using a pneumatically-driven piston vibrator to compact a tank filled with granular material. The intensity of the vibrator can be regulated by changing the pressure of the pressurized air fed ...
-2
votes
3answers
57 views

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 ...
0
votes
0answers
23 views

Measure static pressure with measuring tubes of different diameter

Assume you have a horizontally placed cylindrical pipe with constant diameter. There is a flow of water, through this pipe. You want to measure the static pressure inside the tube, which should be the ...
1
vote
0answers
38 views

How to adjust power requirements for a propeller working against a pressure head [closed]

I'm in the process of building a hovercraft. In order to lift it, I'll need a motor directing the flow of air into a skirt. The specs for the motor I'm looking at say that it can turn a 15x5 dual-...
-1
votes
0answers
13 views

What's the end temperature of a combustion in a closed containment?

Let assume I'm burning a selfsutaining solid fuel in a closed chamber, the combustion temperature is 300°C, and the combustion causes the pressure in the chamber to rise drastically to about 4550 psi. ...
0
votes
0answers
22 views

Is the Ideal gas approximation still valid if I have sizeable dynamic pressure

Say, if I have a hose blowing or sucking air into/outo a bigger compartment, can I still regard the static preassure as obeying ideal gas law?
0
votes
3answers
32 views

Feeling low pressure fluid with high velocity

In Bernoulli theorem physics we say that pressure is low when velocity is high but we feel pressure when fluid hits us why?
0
votes
1answer
66 views

How to calculate the mass of gas needed to fill a cylinder to a certain pressure?

I m tasked with a tricky situation. I need to calculate the exact amount a tank can take in gas. But I dont know the volume of the tank. I just need to make sure that the tank reaches the right ...
-3
votes
2answers
76 views

How would you explain pressure to a school kid?

suppose there is a squarish block (height 2 m) 1*1 on a table and different forces are acting on it from top perpendicular to the surface on top .Suppose it is like one force is of 3N in the middle ...
-1
votes
2answers
55 views

How pressure and velocity is related? And its effect in cavitation

As per my knowledge I think when velocity increases and discharge is constant,the fluid(liquid) molecules get away from each other in the region where velocity is high and that's why they get ...
-2
votes
1answer
47 views

What is true about thrust?

Our book says the force acting on an object perpendicular to the surface is called thrust If two forces are acting on an object perpendicular to the surface both of them will be called thrust or the ...
0
votes
1answer
60 views

Bernoulli Experiment- why is the pressure on the left greater? [closed]

Is the Pressure $P_2$ caused by a reaction force to the fluid-fluid collision, or is it the result of the collisions of the water molecules with the walls at the neck of this experiment. The part ...
2
votes
3answers
75 views

Can a sound wave begin with rarefaction?

Some digital recording samples (audio files) of recorded acoustic sounds present sound waves which begin with rarefaction. Is this an actual phenomena that can occur or is it a result of sound ...
3
votes
4answers
99 views

Why is air pressure higher in winter than in summer?

At the top of a mountain, say Mt Everest, atmospheric pressure is low. So shouldn't the same thing be true for winter season. I.e air pressure in winters should be lesser than that in summers. But ...
2
votes
0answers
25 views

Integrating to find net pressure and force on a sphere by a fluid

How would I go about solving for the net force on a sphere exerted by air pressure as a result of pressure being dependent only on the vertical position of the ball? When the sphere it is placed in a ...
1
vote
0answers
18 views

Why does placing liquid nitrogen in a low pressure chamber lower its temperature?

As you can see in this demonstration and read in this Wikipedia article if you were to place a cup of liquid nitrogen in a low pressure environment then it would reach a triple point and begin to ...
1
vote
1answer
38 views

Maximum density of water

The maximum density of water in its liquid form occurs at around 4°C (under normal pressure p = 1013,25 hPa). If the pressure is increased (or decreased) would the point of maximum density still be at ...
0
votes
2answers
46 views

Pressure in a moving fluid

I’m having some quite large conceptual difficulties which I hope can be resolved by considering this example. When considering the pressure in the sheet very far away from the impact zone the ...
0
votes
1answer
26 views

Does speed of sound in of air change if it is enclosed vs. open air?

To calculate the velocity of a pressure wave (sound) in a fluid, I came across the equation c = sqrt(K/p) where K is bulk modulus and p is density. My question is, if density of air stays constant, ...
1
vote
1answer
33 views

How to calculate acoustic impedance of a megaphone

I'm working on a physics problem that asks how a passive megaphone (simple cone shape) can optimise the transfer of the human voice, compared to not using one at all. I understand that some of this is ...
-1
votes
0answers
18 views

With Bernoulli effect how to calculate pressure drop in adjacent tube to the air flow?

A possibility to draw crank case gases through an oil catch tank under lower pressure (rather than feed back into the carburettor) might be to take a tube to a hole made in the exhaust pipe. Question.....
0
votes
0answers
54 views

Pressure on the outer hull of aeroplane on theoretical emergency landing

I'm trying to figure out the proper way to calculate the pressure on the hull of aeroplane when landing on water. Let's say the horizontal velocity of plane is $1000$ km/h and it starts free-falling ...
0
votes
1answer
43 views

Why are there less bubbles the second time I pour soda in the cup?

I poured some Pepsi into a mug, and it foamed, and I poured until the foam was at the top of the glass. I waited a few seconds for the bubbles to go, and the liquid level was revealed to be at around ...
1
vote
0answers
27 views

Derive the virial theorem from hydrostatic equikibrium

Consider the equation of hydrostatic equilibirium as follows as applied to a stellar object: $$ \frac{dP}{dr } = \frac{-GM\rho}{r^2} $$ I know it is intimately related to the virial theorem but I ...
0
votes
1answer
18 views

Convert negative parameters of Altitude Height into possitive using BMP180 Sensor

I am using BMP180 I2C sensor interface with Arduino and with the help of mentioned below code ...
2
votes
0answers
87 views

Why did this bottle crumple?

These two empty 2-liter soda bottles were left forgotten in the back of a closet for three years. When they went in, they were both in good shape. They were both resting on top of something, with ...
0
votes
3answers
56 views

Work done on a gas enclosed in a container

According to everywhere work done on system of a gas is equal to $p\,\mathrm dV$ but here $p$ is just the external pressure. Shouldn't internal forces be considered while calculating work done thus ...
0
votes
3answers
61 views

Could pressure differentials be used to produce power?

There is potential energy between something like a vacuum in a container and a gas on the outside of it, or vice-versa. Could this energy be harvested in a vacuum, or close to vacuum situation like on ...
-1
votes
1answer
66 views

Calculate the work for moist air adiabatic expansion and compression?

( During expansion some water vapor condenses and is removed from the system. ) More details: Initial conditions: t 25C, p 1013 mB, humidity 100%, then expansion to ~ 450 540 mB through the double ...
1
vote
1answer
51 views

Why we consider pressure do not vary with height incase a gas in a vessel?

Why pressure do not vary with respect to height incase a gas contained in a vessel and atmospheric air pressure varies with respect to height. for example we consider constant pressure in a mercury ...
0
votes
1answer
31 views

Taylor Couette Bernoullis

Has anyone studied a Taylor-Couette flow in the presence of a varying diameter pipe. Is there any research that i can be pointed to to understand how the pressure differences develop in a purely ...
1
vote
0answers
48 views

Pressure buildup in a pipe

How to model the fluid's pressure evolution over time and distance in a pipe, from inlet to outlet, assuming the fluid is water. Say that I have a pipe filled with a fluid with pressure P1 and ...
0
votes
1answer
58 views

Why is pressure greater at the bottom end of a box submerged in water?

It is my understanding that the pressure acting on the bottom end of the box would be greater than on the top. But if we place a box under water, then the height of water above the top end of the box ...
0
votes
0answers
24 views

Theory or method on how to calculate the pressure needed to push a viscous fluid through a narrow slit

I need to calculate the minimum amount of pressure I need to apply to a piece of molten glass to start making it pass through a narrow slit - think 1 kg of glass and a 0.2 mm slit. At this point I ...
4
votes
3answers
76 views

Why, in an open or half-open pipe, must an open end of a standing sound wave have a pressure of zero?

I believe this question was asked in some form before, but I'm not clear on the answer. If a sound wave must equal air pressure when it exits a tube, why is it possible that at many points after the ...
1
vote
2answers
41 views

Pressure due the atmosphere [duplicate]

Usually when we consider the pressure exerted by gas, there is nothing to do with the weight of the gas. On the contrary the atmospheric pressure is defined as the weight of the gasses. What is the ...
2
votes
2answers
94 views

Bernoulli Experiment, unanswered questions

In the bernoulli experiment, the pressure on one side is greater than the other, thus the fluid flows faster through the thinner nozzle.In the image, is the pressure created shown correctly? Since ...
0
votes
2answers
30 views

$p$-$V$ diagram and internal energy

I recently learned that if the initial state is equal to the final state in the $p$-$V$ diagram then the internal energy is equal to zero so that means $Q=W$. My question is how can you know that only ...
10
votes
5answers
1k views

If eardrum vibrates when hit, why don't we hear the air in the room that is continuously moving? [duplicate]

The eardrum is pretty thin.Therefore it should be very sensitive to movement.So, why don't we hear the air that is constantly moving.My guess is that the force of air pressure is not enough.Maybe I am ...
0
votes
2answers
96 views

Potential flow pressure on a smooth surface

For an incompressible potential flow around a smooth rigid body, is it true that the pressure on the surface of the body is proportional to $a\cos^2\theta+b$ where $\theta$ is the angle the inward ...
48
votes
2answers
9k views

How do we get supersonic bullets?

I recently answered a question on the WorldBuilding forum about grenades and bullets. One of the things that came up was that I argued smokeless powder in a rifle round could detonate, but was ...
1
vote
0answers
47 views

Estimating the Pressure of Earth's Center

The pressure of a medium of density $\rho$ and in a graviational field with strength $g$ at a depth of $z+dz$ is equal to the pressure at $z$ plus the pressure caused by the weight of a slab of volume ...
1
vote
3answers
59 views

What's the difference in a PV diagram that is curved versus one that is straight?

So what would the difference be between the graph above versus one that has the same inital and final points but the path is curved. I'm sure it has something to do with temperature, so does it mean ...