Pressure Definition and 999 Threads

We all know that a flowing fluid acquires dynamic pressure as a result of this velocity. But the pressure has been known to be the kinetic energy of unit volume of flow i.e. 0.5 times density multiplied by the square of the velocity. I just want to know how to convert that into units that are...

I performed an experiment where I let water flow out of a measuring cylinder through a hole at the base of the measuring cylinder. I let the water run out for 30s, recording the volume after. I did this for different heights of water in the measuring cylinder, and kept the pressure of water at...

I think the answer is D because both molecules can hydrogen bond with their OH groups, but the C=O bond in ethanoic acid is polar and contributes to dipole-dipole interactions. The solution says B is the correct answer, because ethanoic acid molecules strongly hydrogen bond so that most...

So, the Cp and Cv its very confusing for me. But, i understand what's its happening in this process, so, i use the logic and first i obtain a ecuation for obtain the final temperature ecuaticon: Q=m*C*△T Q=m*C*(T2-T1) T2=(Q+T1)/(m*C) If the process its in constant pressure, i use the Cp valor...

In derivation of relation for pressure of Gas ,(see pic below) the time for rate of change of momentum of molecules should be the time for which the wall of the vessel and the molecules kept interacting with each other, not the time between successive collisions. As circumscribed below, my...

Hi, From suppliers of bearings, some of them specify the maximum bearing (surface) pressure or the maximum load rating (static or dynamic). What's the difference between this two? And which is most commonly used during selecting and calculating bearings in a mechanical design? Thanks in advance,

However, I can't find any proof on this ? Can someone help to explain this ?

I have calculated the wave length of a 36 kHz acoustic wave in 20 °C water to be around 41.16mm. Suppose I have a transducer that produces a 36 kHz acoustic wave and a small water container with a length of 41.6 mm. How will the standing acoustic wave look like, which is produced by the...

Started an irrigation project. There are 4 points in this irrigation system; A, B, C and D. The main water line to the house is 1" diameter pipe. (Point A) The distance from Point A to Point B is approximately 30 feet. Here at Point B the pipe size is reduced down to 3/4" pipe. The distance...

When we talk about systems at constant temperature and pressure, maximum amount of non-PV work can be extracted if process is carried reversibly and in that case it is equal to change in Gibbs energy of the system (decrease in Gibbs energy if system does non - PV work, A.K.A work is extracted...

The method to solving this is to equate forces along a portion of the balloon through which ##\sigma_L## acts, and another portion through which ##\sigma_t## acts. The former potion should be a circular cross section of the cylinder, while the latter will be a rectangular cross section. You will...

All the popular definitions of 'air pressure' that I have seen say: "air pressure is the weight of the column of air above you". This seems misleading to me. - -...

I have read this in my textbook about principles of operation of centrifugal compressor: "The impeller is rotated at high speed by the turbine and air is continuously induced into the center of the impeller. Centrifugal action causes it to flow radially outwards along the vanes to the impeller...

Hi all, A question on the physics behind rapid pressurization (relatively high pressures e.g. 300 bar) and perhaps transients in systems. For simplicity, imagine that we only have a piece of pipe with an initially closed valve on one side and a pressure indicator on the other side. The current...

Basically, I'm working on a project to make active compression garments instead of passive. There are a few materials that can actuate with large recoverable strains, and I want to use them to create the compression. I need to estimate how much pressure they could create based on the recoverable...

I know the integral of a P(V) eqn gives an eqn for work. I was wondering if taking the derivative of a P(V) eqn gives an eqn for change in pressure?

Im confused on working backwards so to speak to find adiabatic work. To find work for this adiabatic process, I either need to know the change in temperature OR the initial pressure (I think?). The issue is that I don't know either the initial temperature nor the initial pressure so I am not...

Let us assume that there are 5 blocks , each of weight W. The blocks are held horizontally by applying a high enough force, ( say N ) to the leftmost and rightmost blocks. Let us say the blocks are numbered 1 to 5 from left to right. So, if i try to draw the free body diagrams, then block 3 will...

What I've done is using the TOV equations and I what I found at the end is: ##e^{[\frac{-8}{3}\pi G\rho]r^2+[\frac{16}{9}(G\pi\rho)^{2}]r^4}-\rho=P(r)## so I am sure that this is not right, if someone can help me knowing it I really apricate it :)

For a steady, non-viscous and incompressible flow, one can apply both Bernoulli's principle (no potentials) as $$p+\frac{\rho v^2}{2} = p_t$$ where ##p##, ##\rho,##, ##v##, and ##p_t## are static pressure, density, flow velocity, and total pressure, respectively, and continuitiy principle as...

Hello! I've come across this forum looking for an answer to an odd question related to energy production. I have no intention of creating infinite energy so don't worry. Imagine a very strong balloon with a cord wrapped tightly around it. The balloon expands pulling the cord which spins a...

Inflatable SUP boards, LEI kites, Inflatable kayaks, and so on get their stiffness by having two layers of airtight materials separated by pressurized air. And it gets stiffer the higher pressure you can contain, or by increasing the separation between the materials. The simplest way to look at...

Hi. A version of the third law of thermodynamics states that no system can be cooled down to absolute zero temperature in finitely many steps. But what about other quantities, for example pressure: Is it possible (in principle) to evacuate a system up to the last gas particle, or would this...

If I knew how much of the gasoline evaporated, then I could use p = nRT/V to fine the partial pressure of the gasoline and add it to the pressure of the atmosphere. So my question is, How do I find how much of the gasoline will evaporate. I would think that the gasoline would evaporate until it...

Hi everyone, In purpose to estimate the corrosion degredation in pressure vessels it is recommended to measure the pressure vessel thickness using an U.S. device. My question is how to determine the number of test points on the shell/caps surface as a function of the pressure vessel size...

As I stated in the summary I'd like to calculate the required pressure and mass of a tank of hydrogen that would allow me to fill a second tank with 10kg of H2 at 700bar. I am trying to get an idea of the feasibility of doing this, putting aside, for now, how the primary tank would itself be...

i have the first convertions of the atmospheric pressure: 1872 lbf/ft^2 = 89,632.6 Pa 2016 lbm/ft^2 = 96,325.4 Pa g= 9.72 m/s^2 But, i don't have idea how pass the air density of "lbm" to international units ;,(. And other cuestion: its fine pass lbm/ft^2 and lbf/ft^2 to Pa simirlarly?

Hello, The question will probably be related to mechanical engineering / chemical engineering / aeronautics. I come from the field of optics and have no background at all on fluid dynamics. I'm trying to calculate the dependence of pressure on distance, i.e. P(x) in a gas flow problem: I...

I did (1300)(9.81)(0.67) and got 8544.51 N/m^2 but unsure if that was the correct route to take. Please confirm or deny if I was approaching it in the correct way!

So I basically took the integral and ended up with W=PVf-A(Vf^3)/3-PVi+A(Vf^3)/3 so 65.7=72*5.3-A(5.3)^3/3-72(2.4)+A(2.4)^3/3 But when I solve for A I get the wrong answer of 3.179 when the answer is suppose to be 5.05. I've checked my calculation with an algebra calculator too...

I have read numerous times that equilibrium vapor pressure (EVP) is a function ONLY of temperature. This at least partly makes sense to me (so I think) given energy of molecules and movement associated with such. But apparently this is not true for the partial pressures? I once thought that...

I add a Figure with the problem and solution. I have difficulty with a solution to the given problem. Why ##F=-kx=Adp##, I do not understand minus sign because we are working with scalars not vectors. It is correct to say that ##\vec{F}=-kx\vec{i}##, but is not correct to say that ##F=-kx##. Can...

We have a product container we purge with nitrogen to create a low oxygen environment The container is roughly 12x12x12 inch. It has an exhaust port with a 1/4 inch poly line that measures 0.17 inch ID. The top of the container is a door with a rubber gasket. We are a little surprised at...

Hello! I am having trouble with this problem I found online,it was listed under the "easy" category yet I am somehow not seeing the trick. First I converted the V into m^3 so that V = 0,015 m^3,than I converted the hPa into Pa so p = 101300 Pa and now I used the fact that ##p1V1 = p2V2 ## We...

The answer is suppose to be 0.9432. Initially I thought the pressure inside the glass ball would just be the same as the atmospheric pressure because these equal pressures would cancel each other out, but obviously that's not true. I can calculate the density of the gas using the equation...

So since the block is at the bottom there's no pressure pushing it up. To calculate the mass and force of gravity, I multiplied the density of the block by its height and cross sectional area and got 564 kg. Multiplying this by 9.8 I got the force of gravity of 5527.2 N. Now to find the force...

Is there any way that I can find concentrations and then find the rate constant, k? And, using them, make an Arrhenius graph to find activation energy (including the catalyst)? Any help would be much appreciated. Change in pressure was found using a Vernier Gas Pressure Sensor. The starting...

Hi, What can be done to avoid trupped bubble air at the top of a pressure vessel without upper hole during hydraulic testing? Also, once the bubble exist what can be done to release it? Thanks

Isn't the formula to be applied ##P= \chi_{solvent}P^o _{solvent}##? in which ##P^o _{solvent}##= 18.7mmHg and ##\chi_{solvent}= \frac{mol_{solvent}}{mol_{solvent}+mol_{solute}}=\frac{9.0 mol}{9.0 mol+0,50 mol}## but seems doesn't leads to the expected result

Hi, I have a valve which is connected to a pipe on both sides. I measure the pressure upstream of the valve. Downstream of the valve is a screw pump. I control my valve using an analog voltage input between 0 and 10 volts. According to the datasheet, the relationship between the analog input...

It's desirable that propane and butane be interchangeable as fuels in gas-burning appliances. However, butane has a higher calorific value. If used at the same pressure as propane it would give a higher heat output. My guess was that the reason propane is set to a higher pressure is to offset...

Hello Everyone! this question is using Indonesian language, i have translated the question at "Homework Statement". The container is filled by water (in Indonesian, "Air" means "Water") i know the the pressure at point X, Y and Z depends on their corresponding depth. my best answer is : Pz >...

I found this interesting thermodynamics problem on another site. I thought PF members might find it challenging to attack. I'm not asking for help since I've already solved it. So pease feel free to present your entire solution if you desire. Chet

Homework Statement:: Calculating airspeed and pressure in a funnel Relevant Equations:: ? Hi all, I hope I posted this in the right place (if not, please let me know). For an art project in school I want to build a funnel to direct air into a set of organ pipes. However, as mentioned, I am...

Today, I was reading about the basics of atmospheric pressure. We all now it is the pressure exerted by the atmosphere on earth. It is quite high i.e ##1.01 \cdot 10^5 Pa ##!. This force exerted by atmosphere is enough to easily crush us. But we do not get crushed because nearly same amount of...

If we just prove (https://www.physicsforums.com/threads/does-every-object-rotate-around-its-center-of-gravity.998359/) that object don't rotate about CG ,why then center of gravity must be ahead of center of pressure ,for yaw stability? Can you explain physics behind this phenomen?

Left and right piston produce same vertical force.On both piston, side force is zero,how this is possible if left piston don't has simetrical shape? Why shape of object is irrelevant when fluid has constant/same pressure around object? How can I prove with integration of pressure over left...

First, I calculated the number of moles of glucose. n = m / M n = 1.8 / 180 n = 0.01 moles of glucose So I checked the combustion reaction. 1 C6H12O6 + 6 O2 -> 6 CO2 + 6 H20 1 + 6 -> 6 + 6 0.01 + 0.06 -> 0.06 + 0.06 I considered the number of moles at the end of the reaction. I subtracted...

In the movie The Abyss an oil rig crew works and lives at the bottom of the ocean in a deep sea structure. There is a compartment where there is an opening in the floor allowing the crew to lower a submersible craft without going through any kind of air locks etc. We all should know from high...

Some notation: - the difference between the heights of mercury, which is effectively the height of the mercury in the open end of the tube is ##h_{diff}## - the volume of gas inside the sealed off end is ##V_{inside}## - the volume of gas when let outside, "normal volume", is ##V_{outside}## -...