Pressure Definition and 999 Threads

Hey everybody! as part of a project i need to solve this problem: i have a small closed (50 mm height, 5 mm radius) tank made of PMMA fiiled mostly by salted water and a bit air. the water get a 200 (C) pulse for a very short time of 20 micro-seconds and start to transform into gas (there is a...

Hello, I have a question that I've been struggling to find an answer to / understand. Probably because my understanding of physics is quite limited :) Before I ask the question, these are the things I take as facts, so please correct me if something is wrong: 1. A speaker in half space...

Homework Statement Homework Equations F= ma P= F/A The Attempt at a Solution a). Assuming the piston is in equilibrium, I'm applying Newton's second law F=ma=0 Equals zero because it is not moving Note: P=F/A which I rearrange to solve for the force for F= PA. This represents the...

I have two pressure vessels (volumes known) at different pressures (known) . There is a connecting tube between them of known diameter. I first want to calculate velocity during the equalization and should easily be able to determine the time to equalization. P1 V1 P2 V2 Cross section of...

Homework Statement I am confused on when will pressure of two states be the same for a piston cylinder device. Below are two problems where one's final pressure equals the initial pressure and one is not. Homework EquationsThe Attempt at a Solution Initially, I thought a piston-cylinder...

Hi everyone. Let me give a little bit of background on the problem I need help understanding. I want to plumb an aquarium that has a sump and move the water from the sump to the main aquarium using a pump and 1" PVC pipe. The total system pipe length is going to be roughly 10 feet total with...

I have 2 identical pressure vessels P1 and P2, exactly 1000 cc each. I pressurise them both to exactly ##1000 lbs/in ^2##. I place one on a spaceship and keep the other beside me. The ship blasts off. As the ship whizzes past me, as a result of length contraction, I see that the vessel on the...

Hello, so i have a question regarding the pressure change inside a rising hydrogen balloon, I know that the pressure change of air outside is decreasing(as we go up = less pressure) And as the balloon is rising it's increasing its volume. but what happens do the pressure change inside the...

Homework Statement Hello. I have a problem, which is as follows: A seat in a concert hall is 84 ft from the tympani. The tympanist strikesa single note. The sound pressure level of the direct sound of the note at the seat is measured to be 55 dB. The first reflection from the nearest sidewall...

Hello everyone, I understand the hydrostatic fluid pressure in static fluids: static pressure varies linearly with depth and the infinitesimal fluid parcels located at the same depth in the fluid experience the same isotropic hydrostatic pressure. By Pascal principle, the atmospheric pressure...

In a closed fluidic system (with a pump), fluid velocity is constant throughout the system but what puzzles me is the pressure drop due to viscous effect. In a horizontal pipe, pressure decreases gradually (assuming low friction) down the pipe due to viscous effect. In this concepts, it's hard...

A liquid in a U-tube maintains the same level in both the arms. When another liquid which does not mix with the first one is poured in it, the air interface with either of the liquids in both the arms will be at different levels. Considering a point at the top surface of liquid A, the pressure...

Greetings All! I am not sure if this is the correct place to post this, but I think that since rocket fuel is considered a chemical reaction, this sections seems appropriate. Right, to the topic. Me and my team from the spaceflight society are looking forward to building a hybrid rocket fuelled...

Homework Statement Two systems in diffusive equilibrium have equal chemical potentials. We can use this fact to solve the following problem. We begin with a closed system consisting of a liquid such as water in diffusive equilibrium with its vapour. At the start, only the liquid and its vapour...

I'm working on my first engineering project in the real-world and I'm hitting a bit of a snag. It's regarding pressure loss analysis in an HVAC system. We have a system that is capable of providing a maximum of 2.0-in.wg pressure at the air handler, but we are finding very little air movement at...

I'm reading up on the use of the valve seen in the link below. On page page 5-6 there is the mentioning of available differential pressure. I struggle with understanding what that means exactly. Say I have a set of main supply/return pipes along a building, with some branches along the way...

Hello, Let me first describe the situation I am thinking of: suppose we consider an object in the form of a square with some thickness (e.g. a mirror). Suppose further, that the gravitational force pulling the object towards the sun and the radiation pressure due to the sunlight are in balance...

Hello! I am reading a derivation for Fermi pressure and the author assumes that the electrons in a box are cooled so much that they occupy all the states in the momentum space from p=0 up to a maximum value of p. Then after he obtains a formula for the pressure, he simplifies the formula...

<Moderator's note: Moved from a technical forum and thus no template.> My daughter, who attends the italian equivalent of US K9, asked me some advice about a physics hydrostatic problem. > Which pressure (in atmospheres) a fireman must use to send water at 12 > meters height. I tried to use...

Homework Statement Hydrostatic force on a plane surface ex: Hydrostatic force on a gate: Homework Equations The Attempt at a Solution why can't we just use the formula in the red box above for problem 3.57? instead I have to use integral I am confused, how does this gate different from...

I read this discussion but I am interested in how the entropy is obtained as a function of pressure. Namely, how can you determine a following integral for an ideal gas: $$S(p) = -\int_{0}^{p} \frac{nR}{p}dp $$ when you need to start from 0 pressure?

Homework Statement In the last picture , we can see that at time between 0 and infinity , the variation of pore pressure across depth is parabolic curve , why is it so ? Homework EquationsThe Attempt at a Solution I think it's incorrect . I think it should be linearly decrease with depth ...

Homework Statement I am trying to show that the pressure drag acting on a sphere is 2πμaU by integrating around the surface of the sphere where U is the speed of the fluid the sphere is in, a is its radius, and μ is the viscosity. Homework Equations The pressure at a given position r can be...

If i have Energy Density (U) -> U.Area= F but F.Area = pressure (p) but p must be U . I'm confused! In which cases we can say that energy density is pressure?

Homework Statement A beam of molecular oxygen containing 1010 molecules/cm3 and average speed of 500 m/s strikes (elastic collision) a plate at an angle of 30º with the normal direction. Calculate the exerted pressure on the plate. Homework Equations P = Impluse x Flux The Attempt at a...

Homework Statement Estimate the pressure increase required to impart 1 J of mechanical work in reversibly compressing 1 mol of silver at room temperature. What pressure rise would be required to impart 1 J of work to 1 mol of alumina at room temperature? For alumina take the molar volume to be...

Homework Statement An pillow is inflated with an pressure of let's say 20 hPa. Afterwards we place a weight of 10 Kg on the pillow, what is the pressure increase within the pillow? P athmosthere = 1013 hPa P cushion = 1013 + 20 = 1033 hPa m = 10 Kg g = 9.81 m/s^2 Amount of air in the pillow...

This may not be the proper forum but i need to find a way to calculate how much effort it will take to move a cylinder using a manual helm pump. The hydraulic cylinder i intend on using is a 32mm bore with a 16mm diameter. Stroke of 178mm. Volume of 107 cc The helm pump (attaches to a steering...

Homework Statement 1.Since the roadster seats only two people, it has only two side windows--one on each side. Each window is aligned squarely on the vehicle, so air can flow straight past the window as the vehicle heads forward. However, the air flowing around the roadster's windshield has to...

Hey! I just came across this text ; from http://www.feynmanlectures.caltech.edu/II_40.html I tried to find "the law of hydrostatics" on the internet, to find no other mention of it. (would appreciate links to more details on it or any ideas regarding the topic) What is really puzzling is how...

How can I calculate the water pump size I need for these sprayers? http://www.amazon.com/dp/B007D2RX1C/?tag=pfamazon01-20 Flow rates : 31.2 GPH. The current system I'm trying to figure out the pump for has a center rezzy and it needs to feed aprox 10, 10' pipes with diametre 1''. I have 108...

Homework Statement Homework EquationsThe Attempt at a Solution I thought the pressure in a water line is in gauge pressure, but the solution suggests that 1630 kPa is in absolute pressure, do we always assume absolute pressure unless otherwise specified?

I have a text that writes a pressure balance for a cylindrical shape of fluid, where the linearized Bernoulli gives the pressure field ##p = p_0+\rho\partial_t \phi : \vec{v} = -\nabla \phi## where ##\vec{v}## is the velocity vector. ##p_0## is the static pressure required to maintain the...

Homework Statement The large cylinder in a hydraulic press has 3 times the surface area of the small cylinder. What force should be applied to the small cylinder to create a lifting force of 7200 Newtons In a hydraulic-brake system, a force of 25 N can be applied to a surface area of 5 cm^2...

Recent discussions on pressure as a source of gravity and the related Tolman paradox have reminded me that few people seem to be aware that even in Newtonian gravity the pressure is related to the potential energy, which I've mentioned a few times on these forums before. This is easy to show...

Homework Statement There is a picture attached showing the entire problem. Equation 2.78 is the Clausius Clapeyron equation. Homework Equations Clausius Clayperon equation. L = L'T (since there is a linear dependence on temperature) The Attempt at a Solution $$ \frac{de_s}{dT} =...

Hi Last did physics about 50 years ago but have become interested in how pressuried fluids behave in sealed containers when they are rapidly agitted or otherwise brought into motion. Envisage a large circular container with a central power driven agitator. Two cylinders are attached . The whole...

Hey Guys! I need some help for solving question 2 of this example as my HSC exam is in 5 days and I want to be able to solve this question if I receive it on the paper. Question: Graph: Answer for Q1 (Just the formula) : Work I have done towards this question: I have realized that from...

Homework Statement Question: https://imgur.com/a/8rUw1 Graph: https://imgur.com/a/Z1oBO Homework Equations Answer for Q1 (Just the formula) : https://imgur.com/a/uesqN The Attempt at a Solution I have realized that from 1-2, there is an increase in pressure, decrease in volume and increase...

Hi all, I have just measured the pressure on a point of a tillage tool and the resulting signals is reported in the following link. In literature, tillage tool are modeled with a constant pressure, but i reality the pressure changes over time and I would like to model the pressure...

Hi every body, I need help to calculate the pressure drop to double wall pipe with information as below, i understand need calculate pressure loss to the straight pipe, elbows and supports but I don't know exactly how. - Fluid : air - Double wall pipe (stainless steel) with outer pipe...

I would like to understand this a bit better, so I am looking for a reference to refer to and not necessarily an explanation in a reply. I have a non-porous membrane of a compressible material wrapped around a solid body. I then draw out the air between the membrane and the solid body. I want...

I sealed my attic door and a set of 3 old windows downstairs with plastic. When everything else is closed up the two sets of plastic become extremely tight and you can see/feel the pressure pushing the plastic into the house. Almost to the point of ripping the tape off holding the plastic. Today...

Hello. I usually heard about electron degeneracy pressure and neutron degeneracy pressure. But I´ve never heard about a proton degeneracy pressure. Why is this?

Homework Statement I don't quite follow the solution to this problem (problem 2.11 in Bergersen's and Plischke's textbook), here are the quoted problem and its solution: problem: solution: Homework EquationsThe Attempt at a Solution My problem is with the solution to (a), it seems they...

I'm trying to understand why $$\left(\frac{\partial P}{\partial T}\right)_V = -\left(\frac{\partial P}{\partial V}\right)_T \left(\frac{\partial V}{\partial T}\right)_P$$ where does the minus sign come from?

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color] Notes: Water density = 1000 kg/m3 Mercury density = 13600 kg/m3 g = 10 N/kg Hi all, please help on this questions. The attempt from me a) (0.7m)(1000kg/m3)(g) = (h)(13600kg/m3)(g) h =...

Assuming all gases in the combustion reaction of benzoic acid (C6H5COOH) behave ideally, what is the "exact" change in internal energy? The context in which this question is being asked is after a calorimetry experiment. For all the intents and purposes of calorimetry, the change in internal...

hi every body, I have a machine with compressed air. the problem is the pressure gauges is not working. and when I take the gauges into other compressed air line the pressure gauge work properly. why this happening ? I need your help

p1=Pa+(pgh) p2=p1+pgh Bulb A SG= 0.87 pressure = 200kn/m^2 Bulb B SG= 13.6