Pressure Definition and 999 Threads

Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled gage pressure) is the pressure relative to the ambient pressure.
Various units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the SI unit of pressure, the pascal (Pa), for example, is one newton per square metre (N/m2); similarly, the pound-force per square inch (psi) is the traditional unit of pressure in the imperial and U.S. customary systems. Pressure may also be expressed in terms of standard atmospheric pressure; the atmosphere (atm) is equal to this pressure, and the torr is defined as 1⁄760 of this. Manometric units such as the centimetre of water, millimetre of mercury, and inch of mercury are used to express pressures in terms of the height of column of a particular fluid in a manometer.

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  1. C

    Maximizing Efficiency: Utilizing a Pressure Cooker for Cooking

  2. A

    Hydrostatic pressure of liquid in a cart on an inclined ramp

    Sorry for my English, I'm Spanish. I am not able to make the force diagram for the liquid. I am still in high school and started now little hydrostatic. If someone can give me a light, I would be very .grateful.
  3. thommy

    Why don't airplanes explode due to pressure difference?

    My question might sound trivial (I'm just a first year physics student anyways) , however I really feel the need to get an answer. Since the pressurized cabins inside an airplane are regulated at about 0.8 atm while the pressure outside doesn't surpass 0.2 atm (at 35 000+ ft of altitude)...
  4. prodigylock

    A What pressure would be needed to cause fusion of water?

    So in a DnD story, someone made a bomb by putting 3375ft^3 of water into a 0.5ft radius sphere and caused it to make a nuke. I was thinking if this was possible then what would actually happen, so I spent an afternoon looking for the answer and only got the pressure and density...
  5. R

    Explaining Pressure & Depth Relationships in Fluids Using Halliday & Resnick

    Homework Statement:: Not a homework problem. I need a conceptual explanation. Relevant Equations:: ##p_2 = p_1 + \rho g(y_1 - y_2)## (1) ## p = p_0 + \rho gh## (2) When deriving equation (1) we use the example of a submerged cylinder in static equilibrium with its top at position ##y_1## and...
  6. iVenky

    How does pressure act in all directions if gravity is downward only

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  7. cwill53

    Calculating Pressure & Density Proportions with Changing Altitude & Temperature

    I got the correct answer to this question with the following calculations, but I do need some correction in terms of what units I'm integrating across. ρ##\rho ## is density. mtot=n##m_{tot}=nM##, where n is the number of moles of a substance and M is the molar mass of the substance...
  8. A

    Rocket propulsion explained only through pressure differential

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  9. S

    Partial pressure of oxygen at a certain altitude

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  10. dedocta

    Plate Tectonics and Evolutionary Pressure

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  11. J

    Understanding Vapour Pressure & Temperature Difference

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  12. DrPython

    Calculate the air pressure needed for a projectile to travel X distance

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  13. Tymofei

    Pressure Differential in Fluid Dynamics: Why More on the '+s' Side?

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  14. B

    Pressure loss pipe system: Conversion from known fluid1 to fluid2

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  15. Adesh

    How does a pressure distribution keep the fluid from moving?

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  16. A

    Vapour pressure of water vapour in air

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  17. PeterDonis

    Insights Is Pressure A Source Of Gravity?

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  18. R

    Calculate the Temperature and Pressure of a melting point

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  19. T

    External pressure when internal pressure is constant

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  20. A

    The derivative of Heat Capacity with respect of pressure

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  21. J

    Engineering Hydrostatic Pressure Sluice Gate - Civil Engineering

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  22. C

    MHB Find the probability of 1 tire with low air pressure P (1)

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  23. MrInventive

    Can Increasing Helium Density Affect Payload in Space?

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  24. I

    Chemistry What are the partial pressures of each gas in the mixture?

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  25. I

    Question about calculating the minimum temperature in hot air balloons

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  26. rjomega

    Effect on Volume of a Change in the Pressure of Compressible Gas

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  27. P

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  28. E

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  29. Adesh

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  30. tanaygupta2000

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  31. A

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  32. Adesh

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  33. il postino

    Calculate the pressure using the Van der Waal equation on reduced variables

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  34. S

    Mercury vapor from blood pressure devices

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  35. K

    I What is the Ideal Plasma Pressure for Successful Fusion?

    I am trying to wrap my head around the concepts in fusion. They talk about ion density, but I don't ever see that expressed in pascals, for instance. Why is that? I understand that confinment time is also important for successful fusion and that they go hand in hand, but I'm not concerned about...
  36. anonymous99

    Why doesn't atmospheric pressure crush us?

    H
  37. OriginalH1h

    Pressure Required to propel something a long distance

    I am making this (hopefully in the correct forum) because I started debating propulsion about objects and the like. The main two questions I want to have answered if at all possible are as follows: How much pressure would be needed to send a person flying? How much pressure is needed to...
  38. Fuux

    Sticky card Application of Bernoulli / Pressure incorrect?

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  39. S

    Compressed air pressure vs hydrostatic pressure

    Hi all, I'm new on here and will start off with what I think is a simple clarification. I'm questioning my workings due to previous work being completed by another engineer and thought this was the best place to ask. Essentially we have compressed air being supplied through a hose, the hose...
  40. S

    Calculate the Pressure that Shrink film exerts on a cylinder

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  41. obstinatus

    Isothermal pressure change in a U-shaped tube

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  42. fsonnichsen

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  43. G

    Pump with intake and compression using different pressure ratios

    Lets say we got a larger cylinder-piston combo and a smaller one. First we move the larger cylinder, filling in with vacuum. Then we pump in air, using the smaller cylinder, isothermally, with variable expansion ratio. Here, we clearly have exp ratio > P_atm/P_final We then compress the larger...
  44. brotherbobby

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  45. P

    Constant Pressure Specific Heat in terms of Entropy and Enthelpy

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  46. C

    Schematics of a high pressure water switch

    Does anyone have internal schematics (or illustration) how this thing work inside? Like how water flow can activate the conduction to the two wires connected? https://www.amazon.com/dp/B01MU3KQCD/?tag=pfamazon01-20
  47. E

    Deriving the electrostatic pressure of a water droplet

    I assumed a uniform distribution of charge within the droplet such that ##E = \frac{q}{4\pi\epsilon_{0}r^{2}}## at the outside surface. I then said that the pressure acting at the surface would be the force on a charge element ##dq## within an area ##dA## on the surface, divided by the area...
  48. brotherbobby

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    Assuming water to flow out of the pipe with the same speed as inside and the thickness of water column ##h_{ab} = h_{cd} = h##, my answer would be ##\mathbf{(P_b = P_c) > (P_a = P_d)}##. My reasoning is as follows : at positions ##a\; \text{and}\; d## the gauge pressure is 0 and the total...
  49. Thijske

    How to calculate the pressure of an explosion?

    Say there's 2 grams of gasoline (vapor) (E85) and sufficient air, how can you calculate the force/pressure of the explosion when this mixture is ignited? The pressure of the mixture before ignition is 400 pascal. The calorific value of the fuel is 45 MJ/kg. The volume in which the explosion...
  50. brotherbobby

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