Force per unit area.
1
vote
1answer
138 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 ...
1
vote
0answers
39 views
How do I calculate the energy balance of a trompe?
I was quite fascinated by the concept of an ancient type of air compressor, called a trompe. It entrains air bubbles into a falling stream of water via the Venturi effect, and extracts the air at a ...
0
votes
0answers
199 views
How much pressure is needed to break an egg if applied from top and bottom?
Everybody knows that you can't break an egg with our fingers when pushing from top and bottom.
I assume if we could squeeze hard enough the egg would break?
3
votes
2answers
135 views
With ideal gases, varying quantity of moles, and having a constant volume how do temperature and pressure behave?
I'm trying to build a simulation of gases so I ended-up trying to use law of ideal gases ($PV = nRT$).
In my scenario:
volume is constant ($V=1\rm{m}^3$);
a known quantity of moles are being added ...
2
votes
1answer
86 views
Difference between Diamond anvil cell and Bridgman cell
In high pressure physics what is the difference between diamond anvil cells (DAC) and Bridgman cells? My understanding is that they are both forms of anvil cell but in the scientific literature I'm ...
3
votes
1answer
69 views
Does the Earth have a semi-solid body at its core because of lower pressure at the center of the Earth?
I have read that the Earth has a semi-solid iron body at its core, even though that object is surrounded by liquid magma.... I'm wondering if this is because of a pressure (and resulting temperature) ...
0
votes
1answer
156 views
thought experiment involving water pressure
If I were to move the syringe up, and cause it to be stationary, how does that effect the pressure at the bottom of the pipe? How does the movement of this water effect the system setup and ...
4
votes
3answers
181 views
How can I keep a smaller water reservoir's water level at half available when being fed from a larger reservoir? [closed]
I'm trying to create my own ultrasonic humidifier. I ordered the misting part which works great but it only functions correctly in shallow water. So I'd like to feed from a large water reservoir to a ...
13
votes
3answers
326 views
Why don't I feel pressure on my body when swimming under water?
If I put a couple of lead bricks on my foot, there would be a definite sensation of a heavy, perhaps even painful, force. Calculating the pressure for $20 kg$ of lead over a $100 cm^2$ area of my ...
6
votes
2answers
185 views
At what velocity does sea water leave a pipe run into a fresh water lake (for equal surface levels)?
If I took a fresh water lake* whose surface is exactly as sea level, and connect it to the sea with a pipe filled with sea water, with both ends of the pipe at exactly the same depth from the surface, ...
4
votes
3answers
128 views
Effect variable cylinder radius has on airflow
Can someone shed some light on the following problem? I'm unable to get any traction on it as I know nothing about fluid dynamics (I'm a computer engineer).
It's a problem I made up over a lunch ...
1
vote
1answer
205 views
Pump pressure required to fill water tower
I have a water pump at a distance of x meters from a water tower located h meters above the pump through a pipe with diameter d. I am not concerned with the exact value just want to make sure my pump ...
1
vote
1answer
112 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
0answers
135 views
What is the pressure in a vertical pipe that has moving fluid through it?
I have a system like this
When the valve is closed, pressure along any point along the thin tube may be found thru pgh. 1. What about when the valve is opened? 2. Does the top of the jar need to be ...
1
vote
0answers
34 views
Can I use computer fans and tubes to lower the air temperature below dew point?
I suppose to build a small dehumidifier, but I am narrowing the question down into its logics.
I have relatively powerful computer fans, water cooling radiator and some metal tubings. With the idea ...
1
vote
0answers
50 views
Determining Water Level
Given a cylinder of a constant shape and size, how can the water level be calculated using the inside surface of the container?
For instance, could the inside lining of the container be a pressure ...
1
vote
1answer
80 views
Does a magnet's field become stronger or weaker in a vacuum?
This article seems to indicate that a magnet (atleast magnetite, it may not apply to rare earth magnets) weakens when subjected to extremes of pressure. This is purportedly the result of a decrease in ...
0
votes
1answer
232 views
Calculate pressure of air trapped underwater
Seal top end of straw, partially submerge straw in water, how do I calculate the air pressure inside the straw?
Bonus points for compensating for any secondary factors like temp, humidity or flex of ...
3
votes
1answer
137 views
Cosmology constant as a negative pressure?
It seems a positive cosmology constant behaves like a negative pressure. However, the positive cosmology constant cause a expanding universe. So I am puzzling about this:
A negative pressure cause a ...
0
votes
1answer
365 views
Determine the maximum height a pump can suck up water
I am working on a homework problem that presents the scenario of trying to raise water from a small reservoir of depth 8 m whose surface is 25 m below a pump that can maintain a pressure differential ...
2
votes
2answers
148 views
Why is a hole in a ball?
I wanted to know why there is a hole in the ball (basketball, volleyball, handball) to fill the ball with air. Why can't the ball come with filled in air and fully sealed so that there is no loss of ...
3
votes
1answer
559 views
If 1 screw can support 120 lbs, how much weight can 25 screws support?
While this is mainly about my personal home improvement project, I figure this would be a good opportunity for some of you to apply your physics skills to a real-world situation.
My situation is ...
3
votes
1answer
414 views
Area under a $pV$ diagram
What does the area under a Pressure volume diagram equal?
I read in my textbook it equals 'external' work done, but why is this?
First of all, what exactly is external work?
Can you get it ...
3
votes
2answers
219 views
Jupiter Core is Solid Hydrogen
I was watching a show on the science channel about gas giants; there is something I do not understand. I am not a scientist, so this may be obvious to some. I learned that there a three states of an ...
3
votes
1answer
115 views
Does the magnitude of pressure on the sides (not the top and bottom) of a volume depend on depth?
I understand that at a point in a fluid, such as water, the fluid will be in equilibrium as the sum of the pressure from all directions will equal to zero. For a volume of water, the reasoning should ...
4
votes
2answers
1k views
Why does the balloon pop?
When we pierce a balloon with a sharp needle, it pops and produce a great sound. But, It doesn't pop when we open the mouth of the balloon (through which we have blown air)...
So, Why doesn't the gas ...
1
vote
1answer
86 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
225 views
Will the siphoning effect help a system pump water upwards if the water's entry and exit points are at the same height?
I am looking to pump water from a pool up to a roof for solar heating (black plastic tubing) and then back into the pool with the original source water. Does the gravitational force of the water ...
0
votes
0answers
87 views
Air pressure measurement - diameter of the point of measurement has affect of the reading
I am trying to measure the pressure of air flowing through the tube.
Air flow is created by a small fan with a controlled speed. I have my digital pressure gauge attached at certain point on the pipe ...
1
vote
1answer
120 views
How can I estimate relative humidity ($e/e_s$) from temperature and dewpoint?
Background
my goal is to estimate vapor pressure deficit ($vpd$) from Relative Humidity ($rh = \frac{e}{e_s}$):
$$vpd = \frac{100 - \frac{e}{e_s}}{100} e_s$$
(from Hartmann "Global Physical ...
3
votes
2answers
218 views
Necessary air pressure in flexible vessel to lift a certain mass
I have the following situation in mind:
A big airtight bag of arbitrary shape with a person standing on it. The bag gets inflated with air to lift the person.
Assuming that the bag is much larger ...
2
votes
1answer
523 views
Relationship between balloon size and pressure
I see numerous websites talking about how a small balloon is at higher pressure than a big balloon. This is a fun counter-intuitive factoid... unless it isn't a fact at all.
Young-Laplace gives
$$T ...
4
votes
1answer
119 views
Flow of momentum is pressure
In the diagonal terms of the energy-momentum tensor, the flow of $x$-momentum in the $x$-direction is the $x$-pressure. Why the flow of momentum is pressure?
3
votes
1answer
88 views
Which heated, partially filled bottle will explode first?
This is in reference to a pasteurization discussion on a homebrewing forum.
I have four closed bottles which will explode if containing too much pressure. Two of them are 50% full (A and B), and two ...
0
votes
1answer
997 views
How much work is needed to compress a certain volume of gas?
I want to know the formula (and what does the symbols stand for) for how much work is needed to compress a certain volume of gas?
3
votes
1answer
220 views
Pascal law with two connected cylinders filled with water, and 50kg stones at both their ends
If I have two connected cylinders filled with water, and 50kg stones at both their ends (pressing both ends of the water) how much weight do I need to add on one side so that one of the stones reach ...
0
votes
1answer
1k views
Ideal gas law, pressure increase and temperature
If I had a container, full with air, and I suddenly decreased the volume of the container, forcing the air into a smaller volume, will it be considered as compression, will it result in an increase in ...
1
vote
3answers
132 views
Water, can it break through temperature?
If water is heaten up to ridicilously high temperatures, is it possible for the atoms in the molecules to lose their bonds?
And if it is possible, isn't this some kind of chain-reaction?
Like you ...
1
vote
1answer
330 views
How thick does steel have to be to be able to withstand 300 bar (sphere)
How thick does the material in a sphere have to be to withstand the (inner)pressure of 300 bar if the material is steel? (With an inner-radius of 2cm)
Atmosphere pressure = same as 0 meter above sea ...
1
vote
1answer
58 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), ...
1
vote
1answer
53 views
Pressure change due to fan removing air from a non-airtight room
The following problem occurred to me today:
Suppose a $100\mathrm{cfm}$ fan is pushing air out of a large room which is airtight except for a $10 \mathrm{cm}^2$ hole. The air pressure outside the ...
1
vote
2answers
122 views
Height of the atmosphere - conflicting answers
Okay. I have two ways of working out the height of the atmosphere from pressure, and they give different answers. Could someone please explain which one is wrong and why? (assuming the density is ...
1
vote
1answer
616 views
Calculate mass of air in a tyre from pressure
How can one calculate the mass of air inside a tyre, given a particular tyre size; a pressure, in $kPa = \frac{1000kg}{m\cdot s^2}$; and assuming room temperature, and normal air composition? I can't ...
2
votes
1answer
310 views
Gas Cylinder Life
Say I have a gas cylinder filled with nitrogen to some volume at some pressure. On that cylinder I have a regulator so that I get a steady pressure out. I wish to discharge the cylinder. How many ...
0
votes
3answers
372 views
Units of Distance, Pressure, and Temperature [closed]
I need to store data.
I'd like to store them in Metric units and use a tool to convert them to and from other units that these data points will be displayed in.
As the title states, my constraints ...
2
votes
1answer
113 views
Is it possible to use a powder-based firearm in space?
A firearm relies upon some kind of explosive powder to drive the slug out of the barrel.
My guess however is that in space (at GEO, or higher) a firearm would be unusable due to the extremes of ...
2
votes
1answer
153 views
Basic Concepts of Water Pressure for Plumbers
I am learning how to install water pipes and I was told that to check if a pipe is leaking water I need to check the water pressure. But I don't understanding how water pressure works inside the ...
5
votes
1answer
311 views
Why is pressure in a liquid the same in all directions?
I'd like answers both in the more intuitive side an on the more precise side.
Thinking of water as "cubes" of water, for example, would allow pressure in the z axis to be independent of the y or x ...
1
vote
1answer
115 views
How would this rapid depressurization of water really behave?
An in-development game(Starbound) recently released a demo of their water physics. At about 39 seconds into the video, a volume of water in a container is released when the cap on the container is ...
-1
votes
1answer
100 views
Liquids, atmospheric pressure [closed]
A. If a digital camera is rated as "water resistant up to 3m" how much pressure can the camera take before it starts to leak?
B. If the back of the camera has an area of 0.02 m squared how much force ...
