Force per unit area.

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1answer
49 views

Methods to solve a vapor pressure equilibrium question with water on the moon? [closed]

"Imagine a tall column of water on the Moon, maintained at a temperature of 50°C and left to the open vacuum at the top. Up to what depth will the water continue to boil? The Moon's radius is 0.273 ...
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0answers
23 views

A block floating on water is pushed inside until it touches the bottom. Will the block come back? [duplicate]

A block floating on water contained in a vessel is pushed inside until it touches the bottom of the vessel and then released. Will the block come back? Bouyant force acts because the pressure on the ...
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1answer
32 views

How can I apply a certain “pressure” (g/cm²) to the ground by dropping a weight?

I'm trying to find a way to apply 100g/cm² to the ground (substrate = snow) by dropping a weight from a particular height. If I drop 250g weight (80cm² area) from 1m, I'll get a velocity of 4.43m/s² ...
3
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2answers
142 views

How does the Moon influence atmospheric pressure?

I have just read in the Telegraph an article entitled Moon overhead makes rainfall lighter, scientists conclude. In that article there is the following statement: When the moon is overhead, its ...
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1answer
68 views

Why doesn't a fluorescent lamp implode even though the pressure difference is very high?

According to Wikipedia, the pressure inside a fluorescent lamp is 0.3% of the atmospheric pressure, so the pressure difference between the outside and the inside of the lamp is almost equal to the ...
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0answers
19 views

Several suction pumps connected to same air flow source in parallel, is this set up unequal?

I have some sensors with built in vacuum pumps that are open to the room exhaust. I have a single sample source (a compressed air tank, connected to a T fitting and I side stream sample from one of ...
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1answer
46 views

Is flow speed between two pressures dependent on absolute or relative pressure difference?

Imagine you have a pressure chamber which is divided by a removable wall in two equal parts. Scenario A) Air pressure on the left side is 1 bar, on the right side it is 2 bar. Scenario B) Air ...
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1answer
88 views

Boeing 737 Homework Problem [closed]

I have done the above problem, but have come out with a rather large surface area. Could someone point out my mistake(s)? Given/Assumptions: I assume $\sum F_y=0$ because it's level and straight. $$...
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2answers
45 views

Gravity acceleration and hydrostatic pressure

I know that hydrostatic pressure $P$ is directly proportional to density $\rho$ and depth $h$. Why does $P$ depend on gravitational acceleration $g$ ? $P=\rho g h$ Is it because the force of the ...
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0answers
21 views

Minimum amount of water to pressurize pressure cooker

What is the minimum amount of water to create enough steam to pressurize a 6qt electric pressure cooker to 11psi( above atmospheric pressure) ? I am not wanting the recommended volume of water to ...
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0answers
18 views

after pressure cooker is removed from heat-source

What happens inside a pressure cooker after it is removed from the heat-source and before the lid opens with atmospheric pressure? Specifically, what happens to the boiling point of the liquid(say) ...
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2answers
67 views

How does the pressure inside car tyre change once the car is lifted/ put back on the ground? [duplicate]

Imagine a car on a jack; how does the pressure change once the car is lifted (all wheels in air - not touching the ground). I'd be interested in knowing whether the pressure will increase or decrease ...
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1answer
57 views

How to calculate the pressure inside hose subjected to weight? (Example)

Example: Suppose we have a garden hose laid on a concrete floor. This garden hose is made out of rubber and is sealed on both sides. It is completely filled with water with no air bubbles whatsoever. ...
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2answers
50 views

How do the Americas Cup Yachts sails work?

With the vast majority of sailing boats its pretty evident how the sails work to harness the energy of the wind to propel themselves forward. However on the modern Americas cup foiling yachts i can't ...
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3answers
207 views

How does pressure cooker work?

If you increase the pressure, the boiling temperature increases as well. In the other direction: if you decrease the pressure enough you could even make water boil at 18 dergees C. However I met this ...
2
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1answer
95 views

Determining intake pressure of a cannula returning blood to an ECMO circuit

What are we trying to figure out: We want to know if it is possible to determine the pressure of the inlet for the catheter that returns deoxygenated blood to the ECMO system to help prevent ...
3
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2answers
124 views

Can I cook an egg by holding it in thermosphere?

It is known that in thermosphere, air temperature is rising sharply with increase of altitude. In upper atmosphere, temperatures can even reach 2000°C or higher: see 2. However, air there is ...
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1answer
49 views

Understanding the relation between pressure, ideal gas and, volume

I was given the following formula which is used for ideal gasses: $$pV = nRT$$ where: p:pressure V: volume n: number of moles R: gasconstant T: temperature now when speaking about vaporpressure ...
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0answers
30 views

How much pressure is need to lift tiles against gravity?

Vitrified tiles of size 600 mm by 600 mm and weighing about 7.5 kg each were laid with cement on floor of a building about a year ago. Building has glasses all around and premises are not occupied. I ...
3
votes
1answer
54 views

Does a trumpet play at a tritone lower without lip vibration?

My trumpet teacher noticed that if you blow into a trumpet for warm-up, without any lip vibration, there is still a slightly audible pitch which is a tritone lower than "expected" in the following ...
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1answer
26 views

Biot coefficient as function of porosity

Can the Biot poroelasticity coefficient $\alpha$ be approximated as a function solely of porosity $\phi$, and if so then how (and under what conditions)? I've read (e.g. 2.02-3 here) that it can, ...
3
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0answers
33 views

Pressure inside a typical white dwarf

Does any one know the order of magnitude of pressure inside a typical white dwarf (better with reference)? Thanks! I think it should be $m_e^4c^5/h^3$ (may be multiplied by $\pi$), which is $10^{22} \...
2
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1answer
104 views

Are low pressure and high pressure areas responsible for rain?

My understanding is that low pressure areas are susceptible to rain. However, high pressure areas have no rain. Now, I want to correlate this with the following areas - Lower Hutt, Wellington , NZ - ...
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2answers
135 views

How does liquid stay in a Pasteur pipette/eye dropper instead of dripping out?

From what I understand about how pipettes work (correct me if I am wrong), when you squeeze the bulb of a pipette, you are removing the air from it and when you dip the end in liquid and release the ...
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1answer
55 views

Pressure gradients at two different sized holes separating 2 chambers at different pressures [closed]

Why is the pressure gradient by the simplified Bernoulli equation higher at the smaller hole?
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1answer
30 views

Coherence of pressure and mass flow in a pipe [closed]

What is the coherence of pressure and mass-flow in a horizontal pipe? Let's assume I have just one pipe with pressure = 1.5 bar at the input and through pressure-losses 1.2bar at the output. Is there ...
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2answers
102 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 ...
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5answers
80 views

Extract energy from the atmosphere? [closed]

Let's say we would fill a long tube with water. Let's say the tube is 1km in height. At the bottom of this tube, the pressure should be much higher than the top. Also, the tube would lead into a ...
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2answers
136 views

What causes the balloon to pop when we push with needle onto it's surface?

I am a bit puzzled because I can see two possible reasons, first one is more common and the other one makes sense too, so here they go: 1) balloon pops because of the fact that after pressure is ...
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2answers
63 views

The Balloon Model for Human Ventilation

The balloon model is often used to show how ventilation works in the human lungs. You pull on the diaphragm, expanding the volume of the container, and the balloon begins to fill up. My understanding (...
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0answers
61 views

Calculation of water pressure [closed]

I have a water tank of 750Ltr capacity installed at a height of 7.5M from ground. How to determine the range of pressure gauge required to measure the pressure from ground level.
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1answer
39 views

Water + RF + Spark = Continuous Fire

Can anyone explain the physics of what is happening in the following video? https://youtu.be/p8xYUDiSGDk?t=37 Is this process Radiolysis? At what radio frequency & power level is h20 ...
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0answers
26 views

Why does individual N2 molecule rise when heated?

I get that hot air is less dense so it rises due to floatation and all, but what happens to one individual diatomic Nitrogen that it increases it's distance from ground? And why is it that the air is ...
4
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2answers
149 views

How to move a bubble which is trapped by the capillary pressure?

I have a question about how to move a trapped bubble in a tube. If we assume to have a horizontal tube, with water on each side of the bubble. The point to the left of the bubble is point 1, while ...
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0answers
20 views

How to Calculate Pressure From Earth up to Space at Certain Height? [duplicate]

https://en.wikipedia.org/wiki/Vacuum#Measurements_relative_to_1_atm https://en.wikipedia.org/wiki/Pressure_measurement#Thermal_conductivity I wonder if there's a clear equation for this calculation. ...
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1answer
42 views

Equation of state in General Relativity versus microscopic description of the fluid

I can't find the answer to the following question. Consider matter fields in General Relativity, assume it to be a perfect fluid. Then its equation of state is, by definition: $$ w=\frac{p}{\rho} = \...
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2answers
61 views

Excess pressure in drops

while calculating the excess pressure in a bubble or a drop we consider one half of the bubble or a drop and equate the surface tension times the circumference of the half of the drop or bubble to ...
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1answer
35 views

Understanding why 2*density of a isolated gas equals half the initial temperature

A vertical cylinder of cross-sectional area 0.050 m2 is fitted with a tight-fitting, frictionless piston of mass 5.00 kg. The cylinder contains 3.00 mol of an ideal gas at 227°C. At what temperature ...
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3answers
81 views

How do you calculate oxygen temperature as atm pressure changes? [closed]

I know that when gases are decompressed the atoms suddenly have a bunch of space and absorb all the heat around them thereby giving the effect that it is cool but how do you calculate this for oxygen ...
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3answers
132 views

When can we consider temperature and pressure as two independent properties of a pure substance?

I thought that pressure and temperature were always dependent properties on each other.But is there any state of a surrounding or condition when these two properties behave independently of a pure ...
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0answers
19 views

Simulating pneumatic tools/devices?

I need to simulate an air compressor/pneumatic system for a train simulator. How do I find the pressure of an air tank after lots of things have used small portions of the compressed air? For example,...
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2answers
62 views

Work done by pressure

The problem is How much work is done by pressure in forcing $1.4 m^3$ of water through a pipe having an internal diameter of $13 mm$ if the difference in pressure at the two ends of the pipe ...
0
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1answer
45 views

Is there a pressure differential between the skin and any parts inside the human body? [closed]

Since most of the human body is never directly exposed to the atmosphere, is there a meaningful difference in pressure between any internal organs and the skin? If so, how do open wounds which ...
0
votes
1answer
38 views

I need to know the pressure of gravity feed elevated water tank [closed]

I have a rain catchment tank holding 5,600 gallons of water 7 feet above the ground. I want to run this water 20 to 30 feet to drip water plants. Currently a hose runs to a computer valve (timer) ...
1
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4answers
583 views

Why does moving air have low pressure?

According to Wikipedia lift in an aircraft is due to an area of low pressure formed above the wings of an aircraft due to the fast moving air there. So why exactly is an area of low pressure created ...
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3answers
193 views

Pressure inside a closed room

I am sitting inside a closed room with a cement ceiling just above my head. The pressure of the atmosphere is exerted on the ceiling from above(outside). But solid cement not being a fluid does not ...
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2answers
43 views

Stuck at Thermodynamics problem [closed]

So I was trying to solve this problem: "What is the pressure generated in the tramcar pneumatic pump tank, after blowing air 250 times, if the tank capacity is 30 liters and the pump takes 600 ...
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2answers
43 views

Atmospheric pressure

What is the significance of atmospheric pressure being referenced as 100 kPa ? Does that really mean 10000 kg/m$^2$ acting upon us ? If we are measuring only collision force on the surface and not ...
2
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1answer
46 views

Gauge Pressure and Bar Pressure [closed]

I ran into a problem trying to calculate the absolute pressure of an isolated system. I was given that the gauge pressure in a tire is 200kPa or 2 bars. To get the absolute pressure I would have to ...
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4answers
111 views

Buoyant force in an elevator

I can't understand why buoyant force exerted by the liquid on a ball attached to a rope in a box having liquid of density $p$ moving in an elevator moving with acceleration $a$ has buoyant force as, $...