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. E

    Pascal's Law - pressure inside the liquid vs. force needed to lift the liquid

    I'm going to steal a picture that was used in a different thread in this forum. [PLAIN]http://img821.imageshack.us/img821/7469/75687957.jpg (both containers are open at the top, and both contain water) I watched an MIT video of professor Walter Lewin, who used these very same...
  2. S

    Gas or vapor and a liquid from another liquid using temperature.

    The boiling temperature of a liquid removes as much heat as is needed to maintain the boiling temperature of that liquid. Nobody can take any liquid to a temperature above that liquid's boiling temperature, right? If they could maybe they would find the boiling temperature of a portion of the...
  3. H

    Project: Launching from liquid

    Hello all, i really need help on a physics project... i am stumped out of ideas.. the task: To build a boat that will propel itself 1 metre forward, then fire a projectile in an attempt to hit a target 2metres away (perpendicular to the direction of travel). The boat must move by either...
  4. Q

    Do we live in a perfect liquid?

    I'm a physics newbie, so forgive me if I'm ignorant sometimes, but I've been trying to learn physics on my own and understand things for the past couple of years, and I'm proud to say that I've come a long way - still got a long way to go. There was an article posted last week about perfect...
  5. Z

    Liquid non metal conductor for railgun

    Hey all! I've return back to my year 12 assignment, the railgun. I got a working model back then, but unfortunately didn't write up a good report. I have the videos on youtube if anyone is interested. The reason for the conductive liquids is because I want to tackle the arcing issue. I...
  6. R

    Potential Energy of a Liquid - Why is it Negative for Small Molar Volumes?

    I was just reading a book on low-temperature physics and stumbled upon a graph that shows the energy of liquid Helium-4 in relation to its molar volume. The graph includes both zero-point energy and the potential energy of the liquid, and the latter goes steeply (basically a vertical line) from...
  7. Pengwuino

    Liquid cooling PCs, why so expensive?

    Liquid cooling PCs, why so expensive?? So I was thinking about getting a new computer which means new water cooling system :D teehee! I was pricing out systems and noticed that some are just so ridiculously expensive. For example, looking at the components vs. stuff I can find on amazon...
  8. B

    Laser light interference on liquid metal. why?

    I wanted to make tiny movements of the Earth visible by reflecting laser light off liquid gallium metal. It did produce nice reflections on my wall, showing dramatic wobbles of very tiny movements of the liquid gallium. It did however produce light interference patterns which I cannot explain...
  9. S

    Liquid Flow Rate: A vs B - Understanding Fluid Dynamics

    Hi. I used google and found this place. I figure its as good as any to ask this question, which I'm sure forces you guys to dumb yourselves down about 3.14 notches. And this very well may not be the place to ask this question, so feel free to tell me to sod off if there's somewhere else I...
  10. Z

    Free surface of a liquid at rest

    Homework Statement The free surface of a liquid at rest contained in a container of reasonably large size is always seen to be horizontal. Can we say that it is a consequence of i) the absence of relative velocity between the liquid and the container ii) the absence of relative...
  11. R

    Liquid Nitrogen Injection Underground Last Defense

    Only assuming that the worst will happen and that will include the complete breaches through the bottom of the sealed containment of all four reactors, wouldn't it be possible, first, and then prudent, second, to be ready to cool these molten masses with liquid nitrogen being injected...
  12. H

    Pumping liquid rad waste to ocean vs land

    something that is going on that seems odd to me is the pumping of the radioactive liquid waste direct to ocean. I am sure there must be a significant amount of long lived/insoluble/particle type rad waste in there? Is there not a good chance these hot particles could get caught up in ocean...
  13. M

    Liquid Tank Design: Design Solution for 100gpm Flow & 10min Retention

    I have 2 locations of approx 80”w x 80”l x 112”h to install a tank(s). The tank must meet the following criteria: 1. Influent: 100gpm continuous flow of ground water dosed with 12% sodium hypochlorite to eliminate ammonia 2. 10 minute minimum verifiable retention time in the tank during...
  14. D

    Liquid Sodium in a sealed tube

    I need to test a system for liquid sodium wicking under high temperatures. The setup is as follows: Solid sodium pellets are placed in a tube which is then purged of oxygen (replaced with Argon). The tube is sealed and then heated to 300-400 degrees Celsius and agitated with a shaking...
  15. D

    Liquid Sodium in a sealed tube

    I need to test a system for liquid sodium wicking under high temperatures. The setup is as follows: Solid sodium pellets are placed in a tube which is then purged of oxygen (replaced with Argon). The tube is sealed and then heated to 300-400 degrees Celsius and agitated with a shaking...
  16. Q

    If gasoline turns from liquid to a high pressure gas

    in internal combustion engines, how do they run hydrogen in these engines like the BMW hydrogen car when hydrogen combusts into H2O?
  17. G

    What Is the Best High-Density Liquid That's Cheap and Safe at Room Temperature?

    So I am trying to find a liquid at room temp., preferably with a low viscosity, non-toxic and non-acidic, that has a specific gravity greater than 1.5 and is fairly cheap. Tall order? I have done a little research and my best bets seem to be Copper Sulfate Pentahydrate, Zinc Chloride, or...
  18. S

    Pressure in water and different liquid

    Homework Statement consider the figures 1 and 2 which show two identical, rectangular wooden blocks Weight of the block: Homework Equations Pressure = F/a Pressure = Density x gravity x height The Attempt at a Solution The weight of the block, i have tried to find...
  19. T

    Help Internal Energy of a Liquid

    In thermodynamics Change in Internal Energy = Heat - Work (\DeltaU=Q-W) During vaporization my Heat is mass*Latent Heat (Q=mL) and Work is Pressure*change in volume (W=P\DeltaV), so \DeltaU=mL-P\DeltaV. Let's take any of the natural monoatomic gases, Neon in this case. \Delta = Volume...
  20. B

    Sphere falling in countercurrent liquid flow

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  21. Z

    Gravitational Potential Energy of Liquid: Why Does It Increase?

    Why does the gravitational potential energy of a non-viscous liquid increase when a body falls through it?
  22. P

    Pressure Difference in Tank with/without Wooden Box

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  23. K

    Heat transfer from gas to liquid during compression

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  24. M

    How to Calculate the Cooling Time for Wine in a Refrigerator?

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  25. S

    Time required to empty a liquid filled contaier through an orifice

    This is not a homework question. I am trying to figure it out myself. Let a spherical shell of radius R be filled with a liquid (full). Now let a small hole of area A be made at the bottom of the shell. Find the time required to empty the shell completely.
  26. P

    Is there some sort of state of matter between a liquid and a gas?

    We've all heard of the three states of matter: solids, liquids, and gases. Recently someone told me that there is some sort of state of matter between a liquid and a gas. Does anyone know what he's talking about?
  27. L

    Volume change when liquid goes to solid.

    Hello! I need some help regarding a simple matter... How do I derive an equation for the increase in volume when a liquid goes to a solid state when I know the density of the liquid?
  28. K

    Forces exerted by a liquid during a tank rupture

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  29. N

    Final temperature of the liquid water?

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  30. B

    Why is CO2 liquid less dense than CO2 solid

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  31. D

    Using mass of copper in both air and liquid to find density of liquid?

    1. A piece of copper whose density is 8.93 gm/cm^3 weighs 180 gm in air and 162 gm when submerged in a certain liquid. What is the density of the liquid? 2. d = m/v 3. I wasn't sure how to compute this but I calculated the volume of the copper based on its density and air weight...
  32. A

    Approximating a collection of particles as a liquid

    This may be hard to explain, but here goes... Say you have one of those little plastic BBs. When there's just one, it behaves like a solid sphere (which it is). But if you have a large number of them, the mass sort of acts like a liquid - it pours and flows and similar things. My questions...
  33. B

    Can vacuum pumping reduce air bubbles when degassing a liquid sample?

    hi, i would like to ask a rather general question. hope this is the right forum. i have a liquid sample that i need to feed into a sample vial (see attached figure for how the sample looks like) through one of its chimneys. every part of the vial is circular in cross section. what i need to...
  34. A

    Why Does Pressure Decrease When Velocity Increases in a Constricted Pipe Area?

    Homework Statement Assume a liquid is flowing through a pipe of cross-sectional area A at pressure P and velocity v. If, at some point, the area decreases, then; -velocity increase, pressure remains same -velocity increases, pressure decreases -velocity increases, pressure increases correct...
  35. C

    How do they cool liquid helium.

    Ok so when they compress the gas and remove the heat until it liquefies then how do they further cool the liquid. I know they can evaporate a little more of the liquid helium to cool it a little bit more. And i couldn't find much on how a pomeranchuk cell works . Any input will be...
  36. W

    Exploring the Role of Graphite in Liquid Metal Bath Formation

    Hi guys, I'm a physicist and would appreciate some direction in helping me understand the dynamics (or chemistry) of graphite in a bath of liquid metal. Eventually the bath is cooled into a solid ingot. There are several different metals which are used (Cu, Fe, Al as well as many alloys). Any...
  37. K

    Liquid Simulation: Cool Visual Effects

    This is a very cool liquid simulation: http://grantkot.com/MPM/Liquid.html.
  38. B

    Calculating Tank Volume from Liquid Depth: A Practical Guide

    Hi guys/gals, I have a problem, my maths isn't that great. I have some underground storage tanks with petrol in them. and I can only measure depth of the liquid at the bottom. however i want to know the volume for disposal purposes. Can anyone tell me how to find the volume given the height...
  39. M

    Semi-empirical mass formula and liquid drop model

    Dear all can anyone explain to me the semi-empirical mass formula and liqiud drop model, I really don't understand what is the difference between them and which one came before the other. I really confused
  40. J

    Partial pressure and liquid water

    Hi everyone I'm reading up on the possibility of liquid water existing on the surface of Mars, and have confused myself! During my reading, I have come across various definitions that say liquid water can exist if the temperature is above 273 K and the atmospheric pressure is above 611 Pa...
  41. T

    Experimentally observed properties of liquid 3He as a superfluid

    Hey everyone, I'm currently taking a thermal physics course and have been assigned a research paper about the thermodynamically arguable aspects of experimentally observed properties of the 3He superfluid. I have been searching for many different sources but have only found a few worthwhile...
  42. O

    Energy Needed Per Second to Sustain a Velocity through a Liquid

    Homework Statement Bacteria use swimming to seek out food. Imagine that the bacterium is in a region of low food concentration. For the bacterium to profit from swimming to a region with more food, it has to reach there before diffusion of food molecules makes the concentrations in the two...
  43. A

    Specific Volume of Boiling Liquid

    Why the specific volume of a liquid decreases with the increase in pressure at saturation temperature and why the specific volumes of vapor at saturation temperature decreases with increasing pressure??
  44. C

    How Much Work to Pump Liquid from a Hemispherical Tank?

    A hemisphere shaped tank with vertical outlet pipe is full of mysterious liquid. Find the work required to pump the mysterious liquid out of the outlet. The density of the mysterious liquid is 300/98 kg/m^3. [Radius is 2m and vertical pipe is 1m] W= F*d =m*a*d =D*v*a*d D=300/98 kg/m^3...
  45. S

    Terminal velocity of an object falling through a liquid

    I have a question regarding the terminal velocity of an object falling through a liquid. Now the speed will increase up to the terminal veloity in a given time. What I do not understand is in this calculation I'm performing (solving the equation of motion for the speed, when acceleration equals...
  46. P

    Liquid Pressure: How Does It Exert Pressure?

    how does liquid exert pressure in all directions? When a liquid is placed in a container, i understand that it exerts pressure on the bottom of the container due to its weight but why does it exert pressure on the sides of the container? is that due to the fact that the molecules in liquid are...
  47. E

    Liquid moving up a containers walls

    In an attempt to create Rochelle salt crystals using cream of Tartar(or what I thought was cream of tartar) and sodium carbonate, I created some strange orange liquid which smelt mildly of ammonia. I decided to leave it in a dish anyway and see if any crystals came out of it. Crystals emerged...
  48. P

    Visualizing Liquid Pressure: A Diagrammatic Guide

    The forces of a liquid pressing against a surface add up to a net force that is perpendicular to the surface. I cannot visualize this. Could someone help me out diagrammatically here?
  49. L

    Liquid Volume of a Frustum of a Cone

    Homework Statement I have been searching online for help with this equation but have found nothing at this stage. I am looking for an equation to satisfy the Volume of a Frustum of a cone. The liquid level is measured via a sensor located in the centre point, top circle(area) of the...
  50. A

    Maximizing Liquid Surface Area: No Work Required

    I want to know how to increase the surface area of a liquid without doing any work. Heating would be counted in work done.
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