What is Liquid: Definition and 1000 Discussions

A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, and plasma), and is the only state with a definite volume but no fixed shape. A liquid is made up of tiny vibrating particles of matter, such as atoms, held together by intermolecular bonds. Like a gas, a liquid is able to flow and take the shape of a container. Most liquids resist compression, although others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly constant density. A distinctive property of the liquid state is surface tension, leading to wetting phenomena. Water is, by far, the most common liquid on Earth.
The density of a liquid is usually close to that of a solid, and much higher than in a gas. Therefore, liquid and solid are both termed condensed matter. On the other hand, as liquids and gases share the ability to flow, they are both called fluids. Although liquid water is abundant on Earth, this state of matter is actually the least common in the known universe, because liquids require a relatively narrow temperature/pressure range to exist. Most known matter in the universe is in gaseous form (with traces of detectable solid matter) as interstellar clouds or in plasma from within stars.

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  1. J

    I Effects of the centre of gravity on aircraft's stability

    I'm working on a feasibility study for the integration of a liquid hydrogen storage tank for a Boeing 737-800. The tank weighs approximately 5000 kg and must be located towards the rear of the aircraft. I understand that this will shift the centre of gravity slightly further back and...
  2. AstroBar

    I want to encase an ice sphere with an edible liquid flavored coating (for cocktails)

    I am trying to figure out how to drop an ice sphere into an edible flavored liquid that directly solidifies into a perfect spherical coating over the ice. So that when it’s dropped into a cocktails it will slowly melt and give flavour and temperature regulation to the cocktail
  3. C

    I Calculating the change of the volume of a sphere using this integral

    I have a spherical cap of liquid (drop) that rests on a substrate. The substrate has a small hole at the base where liquid is pumped into the drop. One way to parameterize the spherical cap is via: $$x = \sin(s)\cos\phi/\sin\alpha, \,\,\,y=...
  4. anjauk2003

    Chemistry Calculate the pressure-volume work for the given reaction

    I dont have an solution Attempt. Maybe something with PV=nRT but this is for ideal gas and H2O is liquid. An other formula they introduced us to is: dE=-P*V
  5. J

    A Can Hamson-Linde cycle liquidize N2?

    Hi ! To me it seems linda cycle can not liquidize nitrogen. Please explain me, can it liquidize N2? Here is how I come to this result: Imagine compressor take nitrogen 1bar 300k and gives 200bar hot, but cooled to 200bar 315k. Next n2 is cooled in counterflow heat exchanges (hex) by cool n2...
  6. K

    B Pressure in a viscous liquid versus non-viscous fluids

    Hc verma, concepts of Physics, vol 1 pg 258 "We define pressure of fluid at the point A as : ##P= F/\Delta S## For a homogeneous and non-viscous fluid, this quantity does not depend on orientation of ##\Delta S## and hence we talk of pressure at a point". Why did the author stress that the...
  7. S

    I So what are the definitions of gas, liquid, solid?

    Obviously, we know intuitively what they mean, but it seems that physicists have developed an objective definition for all of these. If I were to guess, I'd say that: - a gas is vastly less compressible than a liquid or solid (i.e., which are considered in thermodynamics as basically...
  8. ABC83

    B Cooling liquid in rigid container

    Hello, I have a sealed and rigid container, (can't change volume, can allow heat through), 1.0m x 1.0m x 1.0m in size, that is completely full with warm water, let's say at 40°C. The initial pressure in the container is 1atm and the volume of the water at 40°C perfectly matches the volume of the...
  9. L

    Calculating flow rate when emptying liquid from a closed-top tank

    I can imagine the experiment: the pressure at the surface will drop while the tank is emptying (if no air bubbles enter through the evacuation of course, otherwise it restores the pressure atm at the surface). The flow speed decreases as a function of time until the external pressure maintains a...
  10. Ben2

    Rise of Liquid from Horizontal Acceleration

    The only way I get this is to make a the vertical acceleration at the bottom corner and g the horizontal acceleration there. This is from Halliday & Resnick's Physics. I've been unable to find anything there or in REA's Physics Problem Solver. Thanks for any hints submitted.
  11. Engineer_Kosyakova

    COMSOL: Simulation of liquid nitrogen cooling (Help please)

    The InSb sample (parameters 10x10x0.5 mm) is glued with silver glue to a cooled copper table. Liquid nitrogen passes through the table. While the model is at a temperature of 300 K and at a normal pressure of 1 bar. The sample is affected by a beam of electrons, which causes the surface to heat...
  12. Steven Bolgiano

    I Pressure Required to Circulate Liquid in a Closed System?

    Example: 3/4 pvc in closed circuit with pump. Linear distance of pipe=30ft / head 8ft .... so not counting friction, what general description of force can describe what's required to make the liquid circulate?
  13. pmason61

    Conversion from dry KOH to liquid 45% KOH

    Hoping to get my assumptions and math verified here. We have a process that requires 42 lbs of dry flake KOH (90% purity). Looking to find the equivalent volume (liters) of 45% liquid KOH (11.1 molar strength) - being extracted from a 55 gallon drum. 1 liter of liquid KOH has 11.1 x 56...
  14. S

    B What causes the drop of latent heat at lower temperatures in liquid helium?

    The dependency of liquid He latent heat of evaporation on temperature shows a conspicuous maximum. https://www.nist.gov/system/files/documents/srd/jpcrd551.pdf for 4He. Section 16, pages 1264-1266 on pages, 48-50 on pdf. From fig. 16.1 and table 16.3, the maximum is around 3,1 K and 94 J/mol. At...
  15. P

    B How long does it take for the liquid in a 55-gallon drum to thaw?

    I am trying to calculate the rate of thaw for a 55 gallon drum of frozen juice. I know the surface area of the drum is 20,772 sq cm. I know the starting temperature of the frozen juice (-10C) and I know the ambient temperature the drum is currently in (10C). What is the equation that will...
  16. R

    I Vacuum force factors (vacuum created by a "flow through" liquid)

    Greetings all, I'm new here and hope I'm asking this in the correct thread. So, the question is; where you have a vacuum created by a "flow through" liquid witin a large diameter container exerting suction force upon a smaller diameter input tube submerged in a liquid, does the surface area of...
  17. V

    Calculating Pressure in a Flowing Liquid

    According to what I get, the problem clearly says that ##p_2= 500 ## kPa. I can also see that ##p_1 > p_2## since higher velocity means lower pressure in a flowing liquid and we can say that ##v_1<v_2##.
  18. sumatoken

    Study of harmonic motion of a liquid in a V shaped tube

    A V-shaped tube with a cross-section A contains a perfect liquid with mass density and length L plus and the angles between the horizontal plane and the tube arms as shown in the attached figure. We displace the liquid from its equilibrium position with a distance and without any initial...
  19. MatinSAR

    Mass on a Spring semi-submerged in a liquid

    Hi , Can someone tell me wether my answer is corrrect or false ?
  20. A

    Fluid mechanics - Additional liquid capacity due to compression

    A cylindrical tube (diameter = D, width = L) is completely filled with a liquid (density = ρ). A pump pressurizes the system with a pressure P. Consequently, 1) the solid tube is compressed and deformed according to Hooke's law (σ = ε.E), and 2) the liquid is compressed and deformed, following...
  21. Kalaton

    Green liquid that glows when electrocuted in 39 Clues

    Upon reading a book titled The 39 Clues, one of the main characters finds a vial of green liquid and holds it out into a thunderstorm to be struck by lightning to "charge" it. Once it's struck, it is now glowing, appearing as almost pure light and not even warm to the touch. I understand this...
  22. C

    I Simple model of thermal shape fluctuations of liquid interface

    Consider a container filled with two essentially incompressible liquids with densities ##\rho > \rho'## and (respective) volumes ##V##, ##V'##, rotated by a centrifuge in some orbit-based space lab to maintain a roughly constant (co-moving) simulated "gravitational field" g. Let's suppose that...
  23. Ozen

    Bi-propellant Liquid Fuel Engine Pressures Before Thrust Chamber

    Been reading Rocket Propulsion Elements 9th Edition and got approval from my university to design a bi-propellant liquid fuel rocket engine for my senior design project, and I've been understanding everything so far but I haven't quite found an answer to how the pressure works throughout the...
  24. H

    Engineering Hydrostatic Pressure of Ball Floating in Liquid

    Let's say there's an object floating in liquid. The depth of the object below the surface is 𝑑 and its height above the water is ℎ. The density of the ball is 𝑝𝑏 and the density of the liquid is 𝑝𝐿. The pressure above the water is 𝑃𝑎𝑡𝑚. I understand this situation when only the density of the...
  25. D

    B Simple liquid/gas law question and liquid transfer query

    I am so embarrassed that I have forgotten so much of my physics and I am at the point of being away from school too long to remember even the most basics (Mom said no one can ever rob your education but I'm living proof otherwise). So please forgive my inability to discuss this at an academic...
  26. M

    A Resonant frequencies of liquid in a cylinder

    Hi PF! I have been on and off working on a fluids problem for 2 years. I am SO close but the answer isn't coming out clean. I'll highlight the equations I solve and the technique. If you can help me finish this, I'll not only be incredibly grateful but I'll either thank you in the paper...
  27. D

    Problem understanding liquid pressure

    Good morning. I joined this forum to improve my self and give back what i will learn here for the members of this forum. I m confused about the notion of pressure and i will explain the point that i don't understand. since we know that the pressure is the force over surace. and since we know...
  28. guyvsdcsniper

    Evaluation of heat and work for a stirred liquid

    a.)I would say the stirring, a form of mechanical work, is increasing the internal energy of the liquid, releasing heat into the system, which thereby raises the temperature. b.) Work is obviously being done by stirring the liquid. c.)Well we are doing work on a system so W>0 and with the...
  29. BenDover

    Why does combining Hydrogen, Oxygen and Sulphur produce a liquid?

    Hydrogen is a gas, sulfur is a solid, oxygen is a gas, why does combining them to produce sulfuric acid produce a liquid?
  30. K

    Producing Renewable Liquid Fuels from Atmospheric Carbon Dioxide

    The Sasol plants in South Africa are producing liquid fuels using coal and water as the source of energy and syngas, CO and H2. Some refineries are using natural gas as the starting fuel to produce liquid fuels. Both of these processes are not renewable. The US Navy has a process to extract CO2...
  31. M

    Internal Combustion Engines: Liquid Gasoline or Vapor?

    In an Internal Combustion Engine, does liquid gasoline itself burn/combust, or is it the gasoline VAPOR emitted from the liquid gasoline by evaporation that burns/ combusts? (assuming that Oxygen is present in the Air and Fuel mixture)
  32. S

    Engineering Calculating valve sizes for a compressible liquid

    I have converted given pressures from bar gauge to bar abs Inlet pressure = 20 - 1.013 = 21.013 bar abs Outlet pressure = 6 + 1.013 = 7.013 bar abs therefore pressure drop (x) x = {p_1 -p_2 \over p_1 } = {21.013 - 7.013 \over 21.013} = 0.6662542236 bar abs Comparing to the chart values for...
  33. SpectraPhy09

    Pressure due to a Liquid on container Wall

    I have just started this topic so i Don't have much clearity about it . In our school it was tought that Pavg = (Pi + Pf)/2 ...(i) If we have a cuboidal shape container then it should be pgh/2 ryt ? But also Pavg = Ftotal on the wall /A ...(ii) =...
  34. Dario56

    Owens - Wendt Model for Surface Energy of Solid - Liquid Interface

    Owens - Wendt model is used for calculating surface energy on liquid - solid interface and it is given by following equation: $$ \gamma_{sl} = \gamma_s + \gamma_l -2(\sqrt {\gamma_l^d \gamma_s^d} + \sqrt {\gamma_l^p \gamma_s^p}) $$ So, if we use liquid and solid of known surface energy as well...
  35. L

    A slanted cylinder full of liquid about to fall

    The cylinder will cease to be in equilibrium when the sum of the torques on the cylinder calculated with respect to the rightmost point of contact of the cylinder with the plane will be unbalanced. Now, the liquid is homogeneous and the cylinder has negiglible mass so the forces (normal force of...
  36. Dario56

    Vapor - Liquid Equilibrium Equation (VLE)

    Most fundamental equation for VLE is $$ \mu_i^L = \mu_i^V $$ It states that for every component chemical potential must be equal in both liquid and vapor phase at equilibrium. However, in my thermo textbook, this equation is derived for isolated systems while usually when dealing with VLE...
  37. H

    Calculate time of solid passing through a liquid with the given values

    Summary:: We conducted the Marble Race experiment but the data of the time was lost. So I'm wondering if there's a workaround to at least put a rough estimate on it. How long it would take for the marble that weights 6g with a density of 3.4 to cover a distance of 5.8cm passing through a...
  38. 1

    Can some liquid hand soaps smudge your eyeglass lenses?

    My control variables are 1. water hardness level, as I live in Florida, and I lodged at a Ritz Carlton also in Florida. I'm not, in any way, affiliated with any corporation herein. I'm not, in any way, affiliated with any corporation herein. 2. my eyeglasses with $700 USD Nikon SeeMax Ultimate...
  39. E

    Motion of a sphere in a liquid

    in my head this is just a silly problem in which i need to determine the ↓ force (weight) and the ↑force (archimedes bouyant force) and then the difference must be the drag force ↑ (the force that involves velocity) but i can't get any sense out of this answer how is possible for the sphere to...
  40. J

    Finding pressure of gas in u shaped tube with liquid

    The answer is suppose to be 0.9432. Initially I thought the pressure inside the glass ball would just be the same as the atmospheric pressure because these equal pressures would cancel each other out, but obviously that's not true. I can calculate the density of the gas using the equation...
  41. C

    Density of balls submerged in a liquid and connected by a hard rod

    Performing force balance on the two balls, I obtain ## T+\frac{4\pi}{3}g \rho_3 R_1 ^3 = \frac{4\pi}{3}g \rho_1 R_1^3 ## ## T+\frac{4\pi}{3}g \rho_2 R_2^3 = \frac{4\pi}{3}g \rho_3 R_2^3 ## from which I obtain ## \rho_3 = \frac{\rho_1 R_1^3 + \rho_2R_2^3 }{R_1^3 + R_2 ^3 }## and ## 2T...
  42. D

    What to fill a glass bottle with (a liquid that hardens) to lower its volume?

    Homework Statement:: Oil Lamp ( Paraffin help ) Relevant Equations:: Not sure what to write here HI folks, I'm trying to make an oil lamp from an old Vodka bottle. The bottle is the usual 750ml and is in a skull shape bottle. ( maybe you know it ) Anyhow I have all the materials and almost...
  43. jaketodd

    Misc. What's needed to get liquid helium to climb up a beaker? Thanks

    Any idea how much this would cost and how difficult? Should I forget about trying it myself and visit a university? Thanks
  44. Nick tringali

    How does capillary action of a liquid not violate energy conservation?

    I am learning about capillary action of water. As water moves up paper. How is that not violating energy conservation as it is going against the force of gravity. This obviously can't be infinite energy.
  45. R

    How do we maintain the RPM of turbo pumps in liquid rocket engines?

    How do we maintain the RPM of turbo pumps in liquid rocket engine ? and how do we control it ? and in the case of electric pump fed engine (like rocket labs's rutherford engine) is easy but how we do it for other liquid propellant engines ?
  46. H

    Solving an Electrical Engineering Challenge with a Tank of Electrolyte Liquid

    So I am working on a project where I have a tank, which has a volume of electrolyte liquid inside it. This is coupled to a battery which charges it, and gives it energy. I will have a copperband arround it, so i can measure a potential voltage from the electrical field. So what I need to...
  47. F

    I Coexistence of Solid and Liquid Matter: Conditions for Existing One Phase?

    I think in solid or liquid phase, there are many molecule having a very large speed due to random character in moving.So the liquid or solid matter must co-exist with other phase because some molecules escape from surface of solid or liquid matter.Then is there any condition for existing only...
  48. M

    Hydrography: Chemical Liquid A Explained

    Sorry I don't know if I'm the right place. But I would like to know if anyone here knows what chemical liquid A is applied in hydrography
  49. brotherbobby

    Hollow and solid spheres floating in liquid

    The two situations are shown in the figures alongside. The hollow sphere has a thick heavy rim that compensates for the air inside it - both spheres have the same mass ##m_B## and radius ##r_B##. Since the bodies have the same mass ##m_B##, the mass of liquid displaced is the same ...
  50. P

    I Liquid soap pulsing as it's drawn into a syringe

    So here it is. I took a guess but I couldn't really answer, hopefully you can. Slow motion video of pulsations occurring while sucking liquid soap into a syringe.