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Questions tagged [pressure]

This tag is for questions relating to pressure, in the physical sciences, the perpendicular force per unit area, or the stress at a point within a confined fluid.

The amount of force exerted (thrust) on a surface per unit area is defined as ‘Pressure’.

The basic formula for pressure is $$P=\frac{F}{A}\qquad \text{i.e., (Force $(F)$ per unit area $(A)$)}~.$$

The SI unit is ‘pascals (Pa)’. $~1~$ Pa$~ = 1~$N/m$^2$

Types of Pressures are Absolute, Atmospheric, Differential, and Gauge Pressure.

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When separating an Oreo cookie, why does the cream stick to just one side only?

There is probably some reason for this, but I can't figure out what it is. I agree that it probably doesn't happen 100% of the time, but most all of the time, the cream is clinging to just one of the cookie sides.
Jiminion
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What causes the water in this fountain to reverse direction?

In a children's museum, I ran across this fountain. You can adjust the flow rate with a valve, visible at the bottom. At low flow rates, the sheet of water does more or less what you'd expect: it curves downward, eventually falling more or less…
Ben51
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If water is incompressible, how can sound propagate underwater?

Since sound travels as longitudinal waves, sound waves should only be able to propagate in a medium through compressions and rarefactions. However, water, as a liquid, is generally treated as an incompressible fluid. Since compression is essential…
Omnitragedy
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Why does a candle blow out when we blow on it? Our breath is 16% oxygen and only 4% CO2

Don't say that a layer of carbon dioxide covers the flame, because our breath has more oxygen than carbon dioxide. Also, our breath does not extinguish the flame by cooling it as it is itself warmer than the coolness required to extinguish it. So…
Prem
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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 corresponds to drinking water through a straw about ten…
Mark Eichenlaub
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Why does pressure in a thermos increase after shaking up hot water and soap?

Whenever I wash my thermos, I put hot water and then some soap in; then I seal the one end with my hand or use the lid. After shaking it up, if I slowly remove the lid or my hand, it expels a little air. Why is that? Does it have something to do…
Peter Rankin
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Is the weight of the aircraft flying in the sky transferred to the ground?

Is the weight of the aircraft flying in the sky transferred to the ground? Is the weight of people swimming in the pool also transferred to the ground? How can we prove it?
enbin
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Will helium in the tires of a bike make it lighter?

I know that helium balloons float because it is less dense than air. I'm not expecting my bike to float, although that would be pretty cool. I just wanna know if replacing normal air with helium in the tires will produce a noticeable effect on its…
masterwarrior123
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Why doesn't the nuclear fusion in a star make it explode?

I have a rather naive question. In stars such as the Sun, what prevents the whole thing exploding at once? Why is the nuclear fusion happening slowly? I can only assume that something about the fusion is fighting the gravity and slowing the fusion…
sku
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Why do gases have weight?

I know that a gas is made of atoms or molecules moving freely in space. When these particles hit the walls of where they're kept in they cause something called pressure. But these particles never pile up on each other and push a surface down by…
Amir Moeini
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How do we get supersonic bullets?

I recently answered a question on the WorldBuilding forum about grenades and bullets. One of the things that came up was that I argued smokeless powder in a rifle round could detonate, but was challenged on that. Commenters said that smokeless…
Cort Ammon
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What happens when you put water under intense pressure?

Pretend you have an indestructible tube that cannot leak, inside which is water. Imagine that in each side of the tube, you have very powerful pistons What would happen if you compress the water inside? Would it turn into heat and escape the…
Kiran Kharel
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When a cork is pulled out of a wine bottle, why does the inner end often expand more than the outer end?

When I pull a cork out of a wine bottle, it usually expands slightly in circumference. This makes sense: you want the cork to be slightly compressed relative to its natural diameter when it's inside the bottle in order to make a tight seal. But I've…
tparker
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Will a penny ever stand still in the water at a certain depth?

Let’s say I drop a penny in the deepest part of the ocean having a certain depth. Would the penny become buoyant enough to stand still in the water, since the density of water increases with depth? Since the buoyancy of objects becomes greater as…
Justus Bozzi
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Does car tire pressure change with weight of car load?

Does tire pressure measured by a meter on tire gauge change with load? (I am not interested in pressure produced by car tires onto the road). Car spec usually says "inflate to 220kPa normal load, 300kPa full load". Does this mean the measured…
Marek
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