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New answers tagged pressure

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This is a great question. I feel it necessary to point out the level of study and understanding that go behind asking this question. Well done! Here's the way I understand it. You analysis is flawless; in a radiation dominated universe, $a\propto\sqrt t$. That said, it is not correct to interpret this as the photons exerting some sort of pressure that ...

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You are mistaken. Actually, you can melt ice by applying pressure. This is why ice is so slippery, when you step on a frozen lake, you are melting the very first layer of water, and thus creating a very good instant lubricant for you to slide on. Ok, granted, at very high pressures water does become solid. From the phase diagram, to get solid at around 0C ...

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You could measure the deformation of the container. That is, something has to be in contact with the measured medium, except if it behaves different in the electromagnetic spectrum because of a phase change induced by pressure. There will be miniscule changes in mechanical wave propagation(for small pressure changes), but that is dependent on contact. Is ...

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Sorry, but plausible is not likely. Your description has two problems. The big one is the breathing tubes. Once you get down more than a couple of feet, your lungs simply aren't strong enough to inhale against the pressure trying to force the air in them into the tube. And the same pressure will cause all the air in the boat to escape through the tube if you ...

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Is there a way to create energy from water depth pressure? Yes, but you need the water to be able to flow to a lower pressure region. So for example, hydroelectric power could be generated by run a pipe underground from the Mediterranean Sea (which is at sea level) to the Dead Sea which is well below sea level.

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Hydroelectricity, used all over the world, creates energy from the pressure of water. Having made electricity, you can convert it to other kinds of energy. There does need to be motion-energy is force times distance. Just a static force does not give you energy.

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Before the kink it had momentum density $\frac{\vec{p}}{V} = \frac{\rho V \vec{v} }{V} = \rho \vec{v_1}$; afterward $\rho \vec{v_2}$. The change in momentum density is $\rho (\vec{v_2} - \vec{v_1})$. Multiplying by $A v t$ (the volume that moves past the kink in time $t$), we get the change in momentum that must be supplied to maintain the kink (i.e. the ...

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Lets define some variables first. Lets say that the length of the column of air that you trap in the tube between the water level and your thumb is $h_0$ and it is initially at the same pressure as the surrounding air which we will call $P_0$. Lets also define the cross-sectional area of the tube to be $A$. As you draw the tube out of the water, the water ...

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Maybe , depends on the temperature of the outside that it's hotter or cooler. If it does expands, you'll see that some water will drop off the tube . On the contary, if the air volume reduce , there might be some air at the end of the tube because water was vaccummed up by the reduction of air volume. Sorry for lots of grammar mistakes , I'm from Thailand. ...

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Let's assume a one litre $1000$ W electric kettle, filled with $0.5$ kilograms of water at $20^o$ C: It takes 4.2 joules to warm one gram of water one degree Celsius. So, to warm the $500$ grams of water $80$ degrees from $20$ to $100$ takes $168,000$ joules. The kettle will supply $1000$ joules per second, so it'll take $168$ seconds for the kettle to ...

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Before the water boils, the rate that the water becomes water vapor is slow compared to after it is boiling. The pressure inside the kettle does not increase significantly until after the water is boiling. Only after the water is boiling, is there enough pressure inside the kettle to send a stream of air through the whistle.

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The problem in your post is that you don't consider the force resisting the water pressure, which is exerted by the walls of your container. To do this, imagine a two-chamber container, with outer walls infinitely strong, but with a piston in between them which is maintained at its central position by some force that you exert. Chamber A is filled with air ...

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Pressure is synonymous with energy - its a kind of kinetic potential energy, not unlike heat. Kinetic theory relates these two quantities, together with volume. Let's make some assumptions. When we bottle something we expect its volume to stay about the same - the glass shouldn't flex. Also we pretend the bottom of the ocean is a comfy room temperature, so ...

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Yes - you can have a state where increasing the pressure would create a supercritical fluid See Phase Diagram

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The difference between stress and pressure has to do with the difference between isotropic and anisotropic force. There's a Wikipedia section on the decomposition of the Cauchy stress $\boldsymbol{\sigma}$ into "hydrostatic" and "deviatoric" components, $$\boldsymbol{\sigma}=\mathbf{s}+p\mathbf{I}$$ where the pressure $p$ is ...

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Given a stress tensor $\mathbf{\sigma}$, which has 9 components in general, the pressure (in continuum mechanics at least) is defined as $P = 1/3 tr(\mathbf{\sigma})$. So the pressure at a point in the continuum is the average of the three normal stresses at the point. The off-diagonal terms manifest as shear stress. It's hard to say "stress" without ...

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Pressure is defined as force per unit area applied to an object in a direction perpendicular to the surface. And naturally pressure can cause stress inside an object. Whereas stress is the property of the body under load and is related to the internal forces. It is defined as a reaction produced by the molecules of the body under some action which may ...

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The reason is quite simple: the contents of our bodies (blood, bones, muscle, etc) are at the same pressure as the atmosphere. Even if they were not, atmospheric pressure is certainly not enough to get our bones crushed. When a diver is 10m under water, the pressure is doubled (202650 Pa). Any recreational diver can do that. I have been deeper than that, ...

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There are five good answers in this link: Answer 5: It's true that the weight of the column of air above us is very heavy. We can call this weight an external pressure, because it is pushing down on us. However, the reason we, nor other objects, are crushed by the weight of this air is because this external pressure is balanced by our internal pressure, ...

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see Fig. 4 of this reference: http://www.cibsejournal.com/cpd/2011-10/ Pressure is low just upstream of the fan and high just downstream of the fan.

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The Mythbusters have tested this one. You might want to watch the episode :). Myth: You can turn a row boat upside town and use it as a makeshift sub This myth was used in the movie Pirates of the Caribbean -- Captain Jack Sparrow and Will Turner find a row boat on the beach and sneak out into the water with it over their heads. As they enter ...

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Contrary to the accepted answer: The gauge pressure, $P_{gauge}$ at a depth $H$ in a fluid of density $D$, where the acceleration of gravity is $g$, is given by:$$P_{gauge}=DgH$$ since the gauge pressure is the difference between the absolute pressure and the current atmospheric pressure. The absolute pressure is the gauge pressure, measured against ...

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Hydrostatic pressure at any height below the water surface is calculated by P=hdg where h is height below the open water surface and d is density of water and g is acceleration due to gravity So if you want to calculate guage pressure at height h then use below formula P=hdg+P° where p°is atmospheric pressure

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The Wikipedia article answers most of your questions. What are the requirements for hydrogen atoms to go through fusion? Two atoms must overcome the coulomb barrier, which can be done by forcing two atoms very close together, or by leaving them moderately close for long periods of time, which allows them to tunnel through the barrier. Is it a ...

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Don't get too confused by the "bladeless fan" marketing babble. Something, probably a traditional blower, is pushing air around inside the device. This is ducted so that the flow blows in one direction from little nozzles on the inside of a ring. That causes a lot more air to be moved by Bernoulli's principle. Basically, the ring and nozzles converts ...

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This is not altogether correct. In particular, it does not matter what the pressure of the room is (unless you reach extreme values), because actually what is holding the water column is not some "high" value of the pressure at the bottom of it, it is the fact that the pressure at the top of the water column (at the water-finger interface, or in the air ...

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Weight of water is too more to get hold from bottom just by h$\rho$g pressure but actually when you put thumb you cutoff above pressure and then the pressure at bottom then dominates and hold water in straw.You can find the force now using formula above and it will be right to say that the force just due to pressure on bottom surface is $1.01325*10^5*\pi ... 1 Yes, what you have formulated is fine. The pressure acting on the water from the bottom of the straw will be equal to the weight of the water times the cross section area. So$101325\pi r^2$is the force acting from below also. That is precisely why there is an equilibrium and the water is not falling. 0 You mention particles, so I'll provide a micro-scale analogy. In a gas or liquid, particles are always interchanging energy and momentum due to collisions with other particles. So we can treat them as if their velocity and direction is always random and changing. Imagine a line in the middle of a field, with 10 people (say:$10^{22}$particles in a typical ... 2 The answer to this question is quite intuitive when you think about what pressure is: a force per unit area. In a high pressure zone, particles experience a high force, and in a low pressure zone, they experience a lower force. The high force "overpowers" the lower force, pushing the particles from the high pressure zone to the lower pressure zone. You can ... 0 If a monolayer of water molecules is adsorbed on the surface of pore, the van der Waales potential acting on a molecule is increased due to negative curvature of the water surface (eg. concave meniscus) and capillary condensation sets in already below the saturation pressure of water. It shifts the sorption isotherm of the porous material towards higher ... 0 It is not clear from your question whether the gas in the bottle starts out as air, or the only substance in the bottle is water, either in liquid or gas form. I'll assume the latter since it's easier to answer. Once the bottle is closed, ambient temperature doesn't matter. The pressure of the gas part in the bottle will be stricly a function of ... 4 While the capillary pressure in soil is many orders of magnitude lower than the atmospheric pressure, you also need to remember that in soil, the water is still in contact with the atmosphere, and thus is at atmospheric pressure plus capillary pressure. Since atmospheric pressure is orders of magnitude larger than capillary pressure, the pressure on the ... 0 The total pressure of the gas in a closed mixture is the sum of the so called partial pressures of the gasses: the pressure of each gas in that container if it were alone. In a container that you could have in a lab, the differences in gravity in all the points are neglegible, so you can assume the pressure is constant. But, if the vessel is big enough and ... 2 Think about the definition of pressure: $$P=\frac{F}{A}$$ Now, let's consider the definition of a force. $$F=\frac{dp}{dt}=m\frac{dv}{dt}$$ Hence, for a given area and particle mass, the pressure is a function of the velocity: $$P=\frac{m}{A}\frac{dv}{dt}$$ 0 A measure like 70,000 PSI is found by making a dent in a bar, of reduced area, and then stressing it. The ultimate load a beam can carry, for example, is governed by things like cracks in the bar etc, which reduces the minimum cross-section of the bar. Other area-reducing elements are holes drilled for fasteners (which is why welding is being also used). ... 1 It is possible to create solid water with enough pressure. Water has other frozen state which do not contain the standard water crystal pattern. This is called amorphous ice. When we flash freeze organic food, the ice that forms does not conform to the traditional crystalline ice structure. The water does not expand, which prevents the cell walls form ... 1 What you're missing is some practical aspects of modern plumbing. Every modern plumbing fixture(toilet, shower/sink drain) has a trap or "u-bend" in the piping before it connects to the sewer branch or main pipe. This allows a pocket of water to sit in the bend of the pipe to keep sewer gases from escaping back into the room when the fixture is not being ... 3 If You make a simplified force balance of a sinking box, You can identify two main forces: Force associated with box's weight$F_g$acting downwards and buoyancy force$F_b$acting upwards. The formulas are as follows:$F_g=mg$,$F_b=-\rho g V$, where$m$is the mass of the box,$g$is the gravitational acceleration,$\rho$is the density of water,$V\$ is ...

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That is right, deeper the pressure is stronger. But the pressure is not just in one direction it is in every direction. So the velocity will decrease in most cases. But also you have to be aware of the density of the object. You could read this classical description of diving objects "Thrust" on wikipedia. This is a classical effect, in real cases the ...

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