Force per unit area.
2
votes
2answers
27 views
What about negative Pressure?
Here is something I see :
Let's say the ideal fluid(water here) of density $\rho$ is drawn from a source by a motor and thrown upwards with a velocity $v$. Now we take the power of motor be ...
1
vote
2answers
94 views
What is the pressure on an empty pneumatic tube?
At the residence I'm constructing a kitchen digester. The gas is to be collected into an old bicycle/scooter tube - initially as empty as may be after wringing it out..
Will the digester (total ...
2
votes
2answers
65 views
Intuition contradicting answer for calculating pressure
I have a cylindrical container say of some base area $A$. The atmospheric pressure is $P_0$. The cylinder is moved at an acceleration $a$ horizontally right. I need to find which base would have to ...
0
votes
2answers
24 views
High and low pressure area and raining
In the high-pressure area it is mostly likely that there is sun. In low pressure area it is mostly likely that rain will occur.
Because of the law that ...
2
votes
4answers
114 views
Can a diver swim a short distance in great depths without being physically crushed by the pressure?
I recently saw "The Abyss".
Does it make sense that they do dives in these depths (700m) with soft suits?
Also - what is all the depressurization talk about? Why do divers need to depressurize long ...
0
votes
2answers
91 views
Pascal's law: pressure of fluid at different locations
I know that's stupid question, but I'm really confused what my teachers says, so I need to check that theory.
Here are just two ordinary connected containers, which are full of water.
On grounds ...
0
votes
0answers
49 views
Air pressure in balloon
I have to calculate the air pressure inside of an hot air balloon. After some searching I found out that I can use the ideal gas law: PV = nRT (from Wikipedia)
So to get the pressure in the balloon I ...
3
votes
1answer
80 views
Why doesn't soda fizz at high pressure?
In this video, a can of soda is opened in an underwater station at 2.5 atm. The demonstration is that shaking the soda doesn't cause it to explode like it would at normal pressures.
Why does this ...
1
vote
0answers
28 views
Can I maintain a constant relative humidity using saturated salt solution, at greater than atmospheric pressure? [migrated]
At atmospheric pressure and between temperatures of $\sim 0$ to $100^\circ C$, well known relationships between established humidity and given saturated salt solution are available. I.e. ASTM E104 ...
7
votes
1answer
500 views
Why doesn't a bus blow due to internal pressure?
When one travels in a bus, if he's sitting at any window, he will feel that the air is coming inside. If someone is standing at the open door of the bus, he'll also feel that the air is coming ...
4
votes
1answer
45 views
What is the minimum pressure difference for your ears to pop?
I'm assuming the answer to this largely varies from person to person. Assuming you could instantly change the pressure around your head by amount $\Delta p$, what is the minimum $\Delta p$ for your ...
1
vote
1answer
41 views
Distribution of pressure inside a capsule
How would pressure of an ideal gas be distributed over the inside of a capsule (a cylinder with semi-spheres on the ends)? What about the strain on the material? Is there a general formula for how ...
2
votes
1answer
50 views
Thermodynamics, PV diagrams?
My teacher told me that the total amount of work done on or by a gas can be represented by the area enclosed in the process in a PV diagram. This is only valid for non isothermic processes, right?
1
vote
2answers
35 views
Water draining from a height into the bottom of a reservoir
If I hang one 5 gal. Bucket directly above another, put a hole in the bottom of the upper bucket with a tube inserted just inside hanging all the way to the bottom of the lower bucket and fill the ...
0
votes
0answers
20 views
Over-inflating weather balloons
Would it be safe to over-inflate a weather balloon if it isn't going to be used at high altitudes? I've been looking at several different balloons, but they are all measured by their burst diameter ...
2
votes
1answer
48 views
Is this the correct way to I combine multiple interdependant pressure readings?
I want to measure the density in different layers of a suspension. To do this I want to place pressure sensors at different heights. Let's assume that the sensors are not by orders of magnitude more ...
2
votes
2answers
31 views
Gas Circulation Using Pressure Difference
Dear all, see attached picture
Please, is it possible to have the gas recirculated from the gas phase to the liquid as described in the diagram assuming the gas is not soluble in the water.
These ...
0
votes
0answers
13 views
Gas Circulation [duplicate]
Dear all,
Please, is it possible to have the gas recirculated from the gas phase to the liquid as described in the diagram assuming the gas is not soluble in the water.
These are the conditions.
...
0
votes
0answers
16 views
What is the effect of an increase in pressure on latent heat of vaporization?
What is latent heat of vaporization ($L_v$) in the first place? Wikipedia seems to indicate that it is the energy used in overcoming intermolecular interactions, without taking into account at all any ...
1
vote
1answer
55 views
Calculating Air Density Lapse With Altitude (Specifically, pressures)
This might be a bit more of an engineering question, but I'm calculating air density drop-off with altitude, and I'm having some problems calculating the pressure (I'll run through my method). This ...
1
vote
2answers
158 views
How is energy transferred from one incompressible fluid to another?
When you apply pressure to an incompressible fluid the pressure is transferred. If you stop applying the pressure there is no motion. Volume and density are integral parts of calculating how much ...
1
vote
1answer
141 views
How should holes in a Tesla turbine look like?
I think of building a Tesla turbine out of old hard drives.
Now I wonder how to cut ventilation holes in the platters.
On the internet there are a lot of different attempts on that matter. A lot of ...
2
votes
2answers
123 views
Have negative pressures any physical meaning?
Some cubic thermodynamical equations of state predict negative pressures, have negative pressures any physical meaning? Could they be related to negative mass?
2
votes
1answer
49 views
Air pressure relative to a force on a bag?
Assume an airtight bag occupied by air such that the pressure inside the bag is equal to the atmospheric pressure. Assume the surface tension of the bag is negligible.
What is the change in air ...
0
votes
1answer
39 views
Is this a correct interpretation of pressure?
So I am told that pressure = Force per Area --> F/A..
When considering the units of Force I find that force = kg * m/s^2
When considering the units of Area I find that area = m^2
Thus the units of ...
5
votes
1answer
74 views
What if the lid of a pressure cooker was suddenly released?
My dad and I have tried to calculate the strength of the explosion if the lid was suddenly freed. We took some measures:
Lid mass: $0.7 \textrm{kg}$
Lid surface: $0.415 \textrm{m}^2$
Internal ...
0
votes
3answers
74 views
Lethality of sounds and extreme “loudness”
In theory, could pure sound be lethal? How loud would it have to be? Also, which events are the loudest in the universe, and how loud are they? I'm confining attention to events which occur regularly, ...
0
votes
0answers
23 views
Formula to calculate the density of satuared steam
I need to calculate (or look-up?) the density for saturated steam in a range of 8-12 bar. Is there a formula for this? It's ok if it's not perfectly exact.
1
vote
1answer
114 views
What happens to the vapor pressure when I expel the liquid phase from the vessel?
Suppose I put water in a closed vessel and heat it, so the vessel becomes pressurized above ambient pressure. Now, there should be liquid and gaseous water inside the vessel. Since it's under ...
0
votes
1answer
42 views
If a balloon is continuously filled with air and stays at a constant shape and size will there be any empty space in the balloon?
If a container like a balloon but with constant volume is filled, is it possible to pack air molecules so closely together that they don't have any empty space between them? If so, what would this ...
6
votes
2answers
138 views
Hydrostatic pressure on a teapot spout
The phenomenon where water flows on the outside side of a teapot spout is named "The teapot effect", and occurs due to a difference in pressure between water and the atmosphere. Consider the image of ...
1
vote
1answer
44 views
How does a pierced vacuum move?
If a can of compressed air is pierced on the right, air pushes out, and the can moves to the left.
If a vacuum container is pierced on the right, which way does it move? Right? Left? Not at all? ...
-3
votes
0answers
51 views
When do we have $p = -\frac{\partial F}{\partial V}$? [closed]
In what context can we say that :
$$p = -\frac{\partial F}{\partial V}$$
?
1
vote
1answer
59 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), ...
4
votes
2answers
124 views
Physics behind the flow of gas coming out of a balloon
I'm working with stratospheric balloons (latex ones) and I want to put a valve on it so it can float for a longer time. I'm trying to define which valve I should use, which demands I estimate the flow ...
36
votes
11answers
4k views
How long a straw could Superman use?
To suck water through a straw, you create a partial vacuum in your lungs. Water rises through the straw until the pressure in the straw at the water level equals atmospheric pressure. This ...
3
votes
1answer
66 views
Does tapping at the side of a bottle prevent shaken soda from bubbling over?
Anecdotal evidence has it that a bottle of soda that was heavily shaken will not bubble over if tapped at the side multiple times.
Yet I wonder: Has the tapping really any effect? Or could it be that ...
2
votes
1answer
105 views
Drinking juice through a straw
Why we are able to suck more drink through a larger diameter straw than a smaller diameter straw if $p_1 v_1 = p_2 v_2 = Q$ as per Bernoulli's Principle. The pressure difference I create in mouth ...
2
votes
1answer
43 views
Deflection of a membrane
I am currently working on a project which is described as the deflection of a circular membrane. What I am trying to model is the deflection of a piece of plastic film (E=200MPa,v=0.5) when placed ...
0
votes
1answer
28 views
How does a small radius connector affect gas flow?
Assume I have a 1m3 tank of air at 100 psi, they are going to release to a 1m3 tank which has air at 5 psi. There is a meter long pipe connect between two tanks.
How to calculate the flow speed ratio ...
0
votes
1answer
41 views
How does the radius and length of a pipe affect vacuum performance?
Can I use Poiseuille's equation?
Also
If I have a vacuum pump which says that its performance is 30 cubic feet per minutes and I have two pipes (one is radius R1 and L1, the other one is 2*R1 and ...
6
votes
2answers
148 views
Why water in the sink follow a curved path?
When you fill the sink with water and then allow the water to be drained, the water forms a vortex.. And then it starts to follow a curved path downwards by effects of gravity..
Why this phenomena ...
4
votes
3answers
113 views
Is it easier to pump water up or down?
I'm trying to gauge the strength of aquarium air pumps, for use in a vertical hydroponic farm. A curious question arose: is it easier to pump water upwards vertically, or is it easier to pump it ...
1
vote
2answers
151 views
Freezing point of water with respect to pressure.
I know when the pressure is reduced, the boiling point of water is reduced as well. But how does the pressure affect the freezing point of water ?
In a low pressure environment is the freezing point ...
1
vote
1answer
85 views
A water balloon in vacuum: does it boil?
If I put water in a vacuum it will boil. But what if I put this water inside a balloon ?
I searched for answers and fount this video: http://www.youtube.com/watch?v=9q8F3ClUuV0
It seams that the ...
1
vote
1answer
72 views
Hydrostatic pressure at lateral directions
I just read that, with respect to a stationary tiny cube, suspended in a fluid, that has a negligible weight and dimensions:
Pressure is the same in every direction in a fluid at a given depth, ...
0
votes
1answer
68 views
Real world usage; pump flow vs pressure vs pump head, what is more useful in this situation?
I am currently making a water cooling system for my computer and decided to see if I could get some better help here than what people think they know on the computer forums.
So for my cooling system ...
3
votes
1answer
78 views
What pressure or tension occurs in a glass jar when I pour boiling water inside?
Sometimes it happens that when you pour a boiling water into a glass jar, it cracks. Since glass is very hard material and resilient to pressure, the tension must be very high. Is it possible to ...
0
votes
2answers
79 views
Temperature change inside pressure chamber
Let's say there is a pressure chamber with some sort of sample / specimen (e.g. protein crystal) in it. Now I apply a certain amount of gas pressure, e.g. 10 or 20 atm. Let's say I use xenon as a gas. ...
1
vote
0answers
43 views
How to solve state parameters using these givens for an ideal gas?
In a thermodynamic turbine using air as an ideal gas, given that you have a known inlet temperature value $T_i$, a known exit pressure value $P_e$, a known inlet and exit velocity $V_i$ and $V_e$, a ...
