Force per unit area.

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2
votes
2answers
217 views

Balancing forces on a liquid [closed]

My reasoning is as follows Atmospheric pressure = $P_{0}$; Spring stretch = $x$; Pressure under top piston = $P$ Balancing forces on top piston $kx + P S_1 = P_0 S_1$ Balancing forces on bottom piston ...
9
votes
3answers
138 views
+150

Fluids with critical point at ordinary temperature and pressure

Are there any fluids with critical point near STP or that are supercritical at STP? If not would it be feasible to design a molecule for a substance with critical point near STP using theoretical/...
1
vote
2answers
156 views

Rankine Cycle pressure

I don't understand why in (Ideal) Rankine Cycle we assume that pressure remains constant at the boiler and the condenser. Shouldn't water pressure change, when water goes from liquid to vapor (boiler) ...
4
votes
1answer
57 views

Does the force on the bottom piece of a hummingbird feeder depend on the height of the water in the reservoir?

Intuitively I would think that the more nectar you put into the reservoir the more weight it will put on the bottom piece (the tray that holds the open pool of nectar that the birds can feed out of). ...
1
vote
1answer
102 views

How do I find out the excess pressure of the gas supply?

I have to find out the value of the excess pressure of the gas supply in a manometer. I'm not sure how to do this so it would be great is someone could help me. I also have to write my answer in ...
1
vote
4answers
2k views

Specific heat capacity at constant volume VS constant pressure

For an ideal gas, why is the specific heat capacity at constant volume lower than the specific heat capacity at constant pressure?
0
votes
1answer
100 views

Nozzle vs Orifice Water Jug Draining

why is this happening? Water jug draining So why does the water drain faster when you drain a jug through a funnel compared to the hole you make at the bottom of a jug( the hole is the same size as ...
-1
votes
1answer
16 views

Calculate amount of gas flowing in a pipe [closed]

I have two tanks of a gas which are connected to two different pipes and supplied to two different furnaces. I need to keep a check as to what is the quantity of gas (in KG) that is consumed at any ...
2
votes
2answers
848 views

Dynamic water pressure from flow and diameter

I have to test some fire hydrants and need to get the dynamic pressure. For that I know I can use a Pitot tube but, I don't have one. After Googling a lot, I found two formulas allowing to compute the ...
-1
votes
0answers
13 views

Water Mist Problem? [closed]

If a 150 USGPM 20 deg.C water in a 40 mm diameter with pressure of 25 bar need to be reduced to 2.5 bar through an orifice: will the water mist manifest?
0
votes
0answers
35 views

I'm confused in this dilemma about pressure [closed]

Bernoulli principle ensures that when cross-sectional area is small the velocity will increase and so the pressure decrease. So, in a pump the outlet hose area controls the pressure and velocity of ...
2
votes
2answers
37 views

Spring behaviour under high atmospheric pressure

We have a spring inside a chamber. We compress the spring and then let it decompress freely. Will its decompression (its speed and displacement) be the same if the air pressure of the chamber is $1\;\...
0
votes
4answers
171 views

Velocity of a leak in a closed water tank

Bernoulli's equation states $P_1+{1\over2}\rho v_1^2+\rho g h_1 = P_2+{1\over2}\rho v_2^2+\rho g h_2$ In a classic "water tank with an open top and a leak" scenario, "point 1" is the surface water ...
0
votes
0answers
21 views

Bottles Leaking Due to Air Pressure [closed]

Is it possible for essential oils to leak from bottles, that have been sealed, whilst in an airplane due to air pressure? Thank you kindly. SJ
3
votes
1answer
174 views

How to compute this change of Gibbs energy for a Van der Waals gas?

The change of Gibbs energy at constant temperature and species numbers, $\Delta G$, is given by an integral $\int_{p_1}^{p_2}V\,{\mathrm d}p$. For the ideal gas law $$p\,V=n\,RT,$$ this comes down to ...
1
vote
2answers
181 views

Given a slanted pipe

Question: I have a pipeline that is tilted. I know the length of the pipeline, and the pressure (90psi) that is felt at the very bottom. I'm trying to find out how much liquid has leaked out if the ...
-1
votes
2answers
66 views

What happens to gold under immense pressure? [closed]

What would happen to gold if you put it under immense atmospheric pressures? For example 2M atmospheres.
6
votes
4answers
142 views

Will a tennis ball go further if i hit it with the side of the racket?

If i hit a tennis ball 'properly' on the stringing, does it go further than if i rotate the racket 90 degrees in my hand and hit the ball with the same force, but on the side of the frame? I'm ...
2
votes
1answer
355 views

Could fish in plastic bags filled with water float like that?

I saw this gif earlier and it bothered me how the plastic water bags with fish in it are not submerged in water like they would if we don't do anything special with the water inside and outside the ...
0
votes
0answers
25 views

How would I go about calculating the frequency and amplitude of a sound produced by a collision?

How would I go about calculating the sound pressure level, frequency and amplitude of a sound caused by a collision, given the velocities of the two objects colliding, their acceleration, densities, ...
0
votes
2answers
32 views

Pressure in deodorant can

Pressure in a deodorant can is greater than the surrounding pressure but still the can is in equilibrium with the surrounding . Why does this happen. If we apply $F = PA$ then $P_{in}A= P_{atm}A$ and ...
-1
votes
2answers
46 views

Pressure Difference affecting reversibility of a process

It is said that for a finite pressuredifference between system and the surrounding the process is irreversible. From the diagram can you please tell me how the process is irreversible ? Does this ...
-1
votes
0answers
8 views

Pressure factor affecting reversibility of a process [duplicate]

It is said that for a finite pressure difference between system and the surrounding the process is irreversible. From the diagram can you please tell me how the process is irreversible ? Does this ...
1
vote
3answers
122 views

Atmospheric pressure changes on plastic bottle containing a liquid

We have a problem at work and I need some help on a theory. We ship a liquid in plastic bottles using a pump closure. Recently some of the bottles have been arriving to customers having leaked. The ...
1
vote
1answer
41 views

How to find weight of compressed air?

Lets say I have an aluminum canister with an interior volume of $V$ cubic feet (under normal circumstances and pressure, that's how much air it can hold). If I pressurize the canister to $x$ psi, the ...
0
votes
3answers
322 views

Breathing Air Underwater From A Car Tyre

I've seen in many movies and programs the event where a car plummets off the road and in to a body of water, sinking rapidly. The car slowly fills with water as it sinks and the occupant(s) don't ...
4
votes
0answers
37 views

Parabola or Catenary in this case?

Exhibit A: the flexible film sinks into the box due to lower internal pressure inside the box. question is, does the film form a paraboloid or a 3D catenary or neither? this is the usual method used ...
14
votes
6answers
13k 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 ...
8
votes
1answer
1k views

Inflating a balloon (expansion resistance)

I am doing a quick calculation on how to calculate the pressure needed to inflate a perfectly spherical balloon to a certain volume, however I have difficulties with the fact that the balloon (rubber) ...
0
votes
1answer
228 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 ...
0
votes
1answer
36 views

Is there a thermodynamical function $\Xi$ such that $d \Xi = V d P/H$?

Question Is there a thermodynamical function $\Xi$ such that generally $$d \Xi = \frac{V d P}{H}$$ where $V$ is the volume, $P$ the pressure, and H the enthalpy $H=U + PV$? If such a function ...
5
votes
2answers
120 views

Why does saliva on the finger give correct direction of wind?

When we lick a finger and put it up in the air, the side that is cooled is the one facing the direction from which the wind is blowing. But consider this, if we take a cross section of the finger, ie ...
2
votes
2answers
109 views

Submerged water jet

I am trying to calculate at what pressure and speed water from a high pressure water jet will hit an object 100 millimeters away from the nozzle opening, but i can't figure it out. The nozzle will ...
0
votes
1answer
143 views

Pressure, Momentum and Energy: A 'Peculiar' Relation

Is the following possible? $$ P = \frac{p^2}{3E} $$ where $P$ is pressure, $p$ is momentum and $E$ is energy. In what convention is the above relation acceptable? EDIT: The source paper can be found ...
1
vote
2answers
123 views

Is the force exerted by the container on the fluid and the force exerted by the liquid on the container equal?

I came across a question where i was asked to find the force exerted by the walls of a frustum shaped bucket on a liquid inside it . I found the force exerted by the liquid on the walls of the bucket ...
0
votes
4answers
104 views

Why don't high pressure gases stored in containers lose energy?

Containers holding gas at a high pressure don't slowly lose the internal energy of the gas. It seems like the high speed particles would collide with the metal walls and slowly transfer their energy ...
0
votes
1answer
158 views

How to calculate air flow from a pressurized tank?

I am writing an app that deals with simulated air brakes, and I need to simulate the release of air from one container of a given pressure into another container of a lower pressure. It doesn't have ...
0
votes
1answer
224 views

What is the physical fundamentals of Pascal's law

Pascal's law or the principle of transmission of fluid-pressure (also Pascal's Principle) is a principle in fluid mechanics that states that pressure exerted anywhere in a confined incompressible ...
1
vote
1answer
181 views

How to calculate the amout of time for oil to get out from a pneumatic cylinder?

I have a system. You can assume it is just a 1" diameter steel pneumatic cylinder (1 foot long). Assume we ignore the bore size issue at this point. One chamber is filled up by oil (6" of volume), ...
20
votes
2answers
10k views

Why is stress a tensor quantity?

Why is stress a tensor quantity? Why is pressure not a tensor? According to what I know pressure is an internal force whereas stress is external so how are both quantities not tensors? I am ...
3
votes
3answers
59 views

Is there a prohibited region in $P-V$ plane?

Polytropic process generalize the particular thermodynamic processes with $$P V^{n}= \mathrm{constant}$$ Where, if $n$ changes, the curve on $P-V$ plane changes, as shown in the diagram. The orange ...
2
votes
3answers
611 views

Silicone tube with three holes, flow rate, pressure

I have a silicone tube -- a saline solution flows in from one end, and then flows out of three holes of equal diameter and equal distance from each other that are along the side of the tube. What can ...
0
votes
3answers
66 views

Oscillations in U-tube [duplicate]

U-tube, of uniform cross section $S$ and opened at both ends, is filled with a liquid column of length $L$ and density $\rho$. In equilibrium the water levels in both arms are at same height. What ...
0
votes
1answer
25 views

How does atmospheric pressure affect the speed of object?

I was reading things about the Hyperloop One start-up project ( https://hyperloop-one.com/what-is-hyperloop) and I couldn't get any details on how the process works. This is a new transportation type ...
16
votes
7answers
4k views

How can a vacuum implode a metal tank?

An interesting video: youtube video - Railroad tank car vacuum implosion But how is it possible for a metal tank to implode? Even if one can vacuum it, it is subject to 1 external atmospheric ...
0
votes
0answers
42 views

Wind Flow Simuation Equation

I have a data that contains pressure measurements in difference locations. Now i want to do wind flow simulation based on the pressure difference between these places. The problem is i want to do this ...
0
votes
1answer
48 views

Why pressure standing waves have different nodes location with respect to the corresponding displacement waves?

In acoustics the pressure wave has a $\pi/2$ phase difference with the displacement wave. But I do not understand how this leads to a different position of nodes of pressure inside a tube with ...
34
votes
4answers
5k views

What is the energy source if a tall water tank is used to transfer floating objects upwards instead of cables with motors?

Suppose I want to transport some logs from the ground to the roof of a tower. Originally I can use a lift, or some cables, or even move the logs upwards manually; then the energy is converted to the ...
0
votes
1answer
27 views

Can a decompressed airplane cargo hold cause packaging air pads to burst / deflate?

I received a parcel from Germany to Chile recently. The contents were severely bruised due to a lack of packaging material. On second inspection I found a bunch of deflated air pads. It was a ...
0
votes
2answers
21 views

Reason for fluid pressure

What is the physical reason that high pressure regions (say, of air or water), want to expand into low pressure regions? What force is causing them to "equilibrate" the pressure? The only thing I can ...