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. S

    Split of fuel oil consumption to heatup multiple type liquid

    I have three different liquids l1, l2 and l3 stored for 10 days. The liquid are required to be kept in temp x1, x2 and x3. As input i have following: 1) daily temp of all three liquids 2) daily qty i need to keep temp of all three liquid constant - to do that heating is done. Due to...
  2. B

    ElectroMagnetic Wave In Liquid Help with Index of Refraction?

    ElectroMagnetic Wave In Liquid.. Help with Index of Refraction?? Homework Statement Consider the propagation of an electromagnetic wave in some liquid. The y-component of its electric field is given by Ey(x,t)=4.3 x104 V/m sin(5.40E-2m-1x + 6.00E+0 x106 s-1 t). How large is the index of...
  3. T

    Liquid Flow through a ruptured seal

    I am researching flow through blister packs and trying to derive an equation that can relate flow rate to a plunger position. If I cannot describe the problem well, I will upload a picture that can give a better idea. I have an igloo shaped blister pack made of aluminum foil. A plunger moves...
  4. P

    Surface tension of a liquid layer within frame with elastic wire

    Hi, Homework Statement A square frame with a thin crust/layer of liquid with surface tension γ is given. Into the plane of the frame an elastic wire of circular shape with radius r_0 is inserted. The thin crust/layer of liquid is then burst (by pricking) and as a result of the force of...
  5. M

    Is there some liquid planets out there?

    Is there some liquid planets out there? well there are gaseous planets... what are the laws that avoid the existence of a giant liquid planet with a little rocky nucleus?
  6. Gh778

    Pressure forces from a liquid in rotation

    Hi, A liquid in rotation give two kind of forces: 1/ centripetal 2/ pressure forces (Fa, Fb in the drawing) I'm ok that centripetal forces can't give energy (we lost kinetics energy) but Fa/Fb seems in direction to external circle, why it's not possible to recover energy from these...
  7. H

    What gives a liquid energy to flow ?

    The pressure difference sure.The point where there is higher energy in order to attain lowest level of energy moves towards region of lower energy, but if this liquid is viscous enough, doesn't the whole energy get lost during flowing? then how is the pressure level or rather the energy level...
  8. K

    Question about the difference of pressure between two point in a liquid

    Hi guys, sorry if the question seems too basic or simple, but i can't seem to grasp the concept about pressure here. say, a cylinder filled with water; ------------ °A °B ------------ at point A, the liquid pressure is lower than it is at point B , as there's a...
  9. P

    Liquid flow over a conveyor belt

    1. A conveyor belt with one end immersed in a glycerin tank is used to transport small amounts of glycerin to a second tank. The belt surface is completely smooth, flow is laminar, and the specific weight of the fluid is 60 lbf/ft^3 with the belt velocity equal to 1 ft/s. Determine the volume...
  10. K

    Bulk Modulus, Expansion Coeff. and compression of a liquid in a piston

    Homework Statement A liquid is enclosed in a metal container that is provided with a piston of the same metal. The system is originally at a pressure of 1.00 atm (1.013*10^5 Pa) and at a temperature of 30.0 C. The piston is forced down until the pressure on the liquid is increased by 50.0 atm...
  11. S

    Why Do Elements Behave Differently as Gas or Liquid?”

    Hello, why the same quantity of different elements behave in the same way (take about 22,4 L) when they are gas and they don't when they are liquid ?
  12. S

    Green Liquid Leaked from CT Secondary Terminal Board of 132 kV GIS

    Hye everyone! An unknown thick-and-sticky green liquid was found leaked from 2 out of 9 feeders, of our 132 kV Switchgear. The liquid was leaked through the cable gland that connected to the Secondary Terminal Board insulating cap of the Current Transformer, at the GIS. I had done: 1)...
  13. B3NR4Y

    Force Exerted By a liquid integration problem

    Homework Statement A rectangular swimming pool is 20 feet wide and 40 feet long. The depth of the water varie uniformly from 3 feet at one end to 9 feet at the other end. Find the total force exerted at the bottom of the pool.Homework Equations The force F exerted by a liquid of constant...
  14. C

    Increase in Wavelength of an LED Immersed in Liquid Nitrogen

    Hi, I've been working on an experiment where I dip LEDs into liquid nitrogen and note the color change. All online sources I've seen predict that the wavelength of the light emitted by the LED will decrease upon immersion. What I've been observing, however, is a sudden decrease in...
  15. R

    A test-tube filled with a liquid and was swing around

    Homework Statement A small cylindrical test-tube of inner radius R is initially filled with a liquid up to height ##h_0##. The tube is connected by a long rope of length ##L## (##L»h_0##) and swinging horizontally with a constant angular velocity ##ω##. There is a tiny round hole of radius...
  16. T

    What Are the Electrical Resistance and Heat Capacity of Liquid Nitrogen?

    I have two questions for you guys A) what is the electrical resistance per meter of Liquid Nitrogen and B) What is the heat specific heat capacity of Liquid N.
  17. V

    Liquid Crystal Lasers: Properties, Photonic Qualities, and Optimization

    I'm writing an essay on liquid crystal lasers and have written the intro to my paper. Can I just double check with you all that I haven't written anything that's wrong? Thanks. Please let me know if I should also post the source I used. It's the first time I've posted something qualitative so...
  18. R

    A rotating container injected with a liquid

    Homework Statement A massive cylindrical container of inner radius ##R## is rotating freely with an initial angular velocity ##w_0##. A liquid of density ρ is slowly injected into the container, until the container is fully filled except the center of the container. The angular velocity of the...
  19. Gh778

    Thermodynamics cycle with liquid and gas

    I'm trying to find why this thermodynamics cycle is not possible but I don't find. The only problem for me is at step 3, the gas can't become a liquid but why ?
  20. E

    Medical Girl drinks liquid nitrogen, has stomach removed

    An 18-year-old teenager has had to have her stomach removed in an emergency operation after drinking a cocktail containing liquid nitrogen. http://www.bbc.co.uk/news/uk-19878511 Question? How does she eat food without a stomach? Carry a bag?
  21. R

    Liquid oscillating in a U-tube problem

    Homework Statement A U-tube has vertical arms of radii 'r' and '2r', connected by a horizontal tube of length 'l' whose radius increases linearly from r to 2r. The U-tube contains liquid up to a height 'h' in each arm. The liquid is set oscillating, and at a given instant the liquid in the...
  22. S

    Direction of pressure in a liquid

    In a liquid, when we use P=hρg, how do we take the h? I always thought that we take it from the bottom of the liquid but in a question, they showed that you can take it from the top so I'm pretty confused about this. Here is an example: http://postimage.org/image/oki3fq131/full/ So from this...
  23. U

    Instability of Liquid Jets: Incorporating a forcing function

    Hi, I am working with a droplet generation system that is designed to produce monodisperse droplets. A periodic disturbance of appropriate frequency (kHz) is applied to a piezoelectric ceramic, transferred to an orifice disk (fitted within the ceramic by means of a Teflon O-ring), then sent to...
  24. R

    Liquid being pushed out of a nozzle - how to calculate it?

    Hi guys, I'm relatively new to physics, so please bear with me. :) Let's image we have a cylinder like this, filled with 8760 mm3 of liquid, with a nozzle on one end and a plunger on the other. An explosive charge goes off behind the plunger, releasing 45 joules of energy, and pushing the...
  25. I

    Plastics to tolerate -300F for liquid nitrogen generation

    Maybe someone here will have an idea where I can get some information. I am planning on making liquid nitrogen from air and will need to regenerate waste gas. This gas will be very cold (-300F) and will get transported through some tubing system. Is anyone aware of any plastic tubing material...
  26. Eagle9

    Can the atomic liquid Hydrogen exist?

    Imagine that we have got some vessel under standard temperature and pressure filled with atomic Hydrogen inside and the electrons of these atoms have got the same spin and therefore they cannot join into Hydrogen molecules, so the process of recombination does not occur. Then we begin cooling...
  27. A

    Liquid Solar Generator: Can It Work?

    If I had a black liquid that was thin, and I had a transparent liquid that was just lighter than the black liquid but didn't mix with the black liquid, and I put them in a dish out in the sun would the black liquid absorb the photons causing it to heat up and rise during the day, and cool down...
  28. J

    Velocity of Liquid: Pressure & Density Factors

    I am trying to determine the velocity of a liquid. The density of the liquid is .885 g/cm3. The pressure at which it is being forced is 17236.89 kpa. What else do I need to know? I am looking for a formula to help me in other calculations with different pressures and densities. Thanks in advance...
  29. I

    Making liquid nitrogen from air

    Has anyone done this as a DIY project? I want to use a refrigerator compressor with counter-current coils.
  30. T

    Specific Heat of Liquid Saturation Line and Vapour Saturation Line in RefProp

    Hello There, So I made a plot of some specific heats in refprop, and I chose the "Draw Saturation Lines" option. When I did this, the follow chart was produced. http://i.imgur.com/h34Pq.png Now my question is, what are these saturation lines representing? -TP
  31. G

    Viscous liquid between two circular discs.

    Homework Statement That is the problem statement. I can't seem to get started on part a. For part b I can find the velocity profile of the viscous liquid form the equations of motion relating velocity and change in pressure, find the avg velocity, and find the change in pressure from...
  32. H

    Bouyancy and liquid separation

    Would it be true to say that boyancy, as in helium rising and liquids of different densities separating, with the densest at the lowest point, is an indication of gravity's natural tendency to attract the most dense mater to its centre point? If so is the Schwarzschild radius a natural...
  33. M

    Change of relative permittivity of liquid and solid water

    Dear Physics Forum Users Commonly, the relative permittivity of liquid water is reported to be \epsilon_r = 78.0\epsilon_0, \epsilon_0 being the dielectric constant of the vacuum. For ice (solid water), \epsilon_r = 4 \epsilon_0 (heard it in a talk once). Is it correct to interpret the...
  34. M

    Why does ice cool liquid more than 32 degree aluminum cubes?

    (that's Fahrenheit of course) For that matter...0 degree F aluminum cubes doesn't cool a room temp liquid as much. frozen H2O cools liquid off much much much much faster and more (in total temp drop terms) than equal surface area "cubes" of aluminum, cooled to -20C. (I've done the...
  35. H

    Pressure of liquid given radius, help please

    A test tube filled with water is being spun around in an ultracentrifuge with angular velocity. The test tube is lying along a radius and the free surface of the water is at radius r(o). Show that the pressure at radius r within the test tube is: p = .5(p)(angular velocity)^2(r^(2)...
  36. D

    Calculating Liquid Level in 38,500 bbl Tank Facility

    So I work for a drilling company that stores oil in large cylindrical tank facilities. The total volume of each tank is 38,500 bbls. In each specific tank facility, a radar tank gauge sits atop a 10" pipe inside the main tank, measuring the level of the liquid inside the pipe. Usually, a...
  37. A

    What is the Entropy of Liquid Nitrogen at 77.244K and 1bar Pressure?

    Hi All, I tried to find entropy of liquid nitrogen in various data books, using nitrogen's CAS number, MSDS, but I was able to get the entropy of nitrogen till only 100K, not below that. Does anyone know what's the entropy of liquid nitrogen or that where can I find it? Thanks!
  38. H

    Pressure inside a bladder when subjected to an outside liquid pressure

    If I have a bladder (or balloon) that is charged with 300# of a nitrogen gas at a normal atmospheric pressure outside the bladder, and I then enclose the bladder and subject that bladder to a liquid pressure of 25# on it's outside surface area but inside the enclosure. Assuming a constant...
  39. M

    Magnetohydrodynamics - Plasma or Liquid more conductive?

    Sorry, I am not a physics major - I apologize in advance if this question is ignorant or if this was asked already. What would be the most effective as a Magnetohydrodynamics weapon? Assuming normal ionized air, would a liquid (liquid silver and salt water) or some type of plasma...
  40. S

    (?) on making your on liquid cooling system?

    I was interested in liquid cooling system for my computer tower and had a few (?)s 1. How can i make my own liquid cooling system? 2. Is it cheaper than fans? 3. can i make a liquid cooling system cheaply? 4. Does it look cooler than fans? 5. If i can make my own liquid cooling system can i...
  41. V

    Examples of substances (elements or compounds) that sink in their liquid states.

    examples of substances (elements or compounds) that sink in their liquid states. (solid state is denser than liquid state compared to water) :smile:
  42. S

    Help with liquid transfer through tube

    Hello, Have you ever drank through a straw? Notice how there is always drink left at the end that you can't drink? I believe the volume of this liquid is the same as the volume of the bore of the straw. Now, my question is; Is there a way of pumping a small amount of liquid (2-5ml) over a...
  43. C

    Thermochromatic liquid crystals, how do they change color?

    If you look at liquid crystals in things like moodrings and LCthermometers then you will notice that they can change color when heated. Now I have looked on the internet and found that it has to do with the The cholesteric (or chiral nematic) liquid crystal phase, where they align with each...
  44. S

    Behavior of Liquid Nitrogen at 3000psi & 6000psi

    hi all How would nitrogen behave at 3000psi? or 6000psi? assuming it starts at liquid form and at 1 atms pressure heated to 20 Celsius. thank you
  45. H

    Heat added to water = (Heat absorbed by liquid) + (Heat

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  46. P

    Falling object viscometer non-transparant liquid

    For a coursework, I need to derive the equations behind a viscometer. This viscometer has a free falling object in a non-transparent viscus fluid but it doesn't necessarily need to be the traditional sphere. The restriction only is that the object is connected to a thin stick which is used to...
  47. M

    Spin liquid states and conductors

    Hi, All articles on spin liquids I've seen treat them as insulators. This is understandable in the context in which they were first introduced i.e. the resonating valence bond state in which every electron is singlet-ed with every other, and thus essentially blocking conduction. Given...
  48. A

    Ice Cubes & Liquid Water - Thermodynamics

    Homework Statement Four ice cubes at exactly 0 \ { }^{\circ} \text{C} with a total mass of 53.5 \ \text{g} are combined with 115 \ \text{g} of water at 75 \ { }^{\circ} \text{C} in an insulated container. If no heat is lost to the surroundings, what will be the final temperature of the...
  49. berkeman

    Small Liquid CO2 Manufacturing Machine?

    At my work, we go through a lot of liquid CO2 (LCO2), and dealing with the 500 pound LCO2 dewars is a real pain. I'd like to look at options for us making our own LCO2 instead, but have been having trouble finding information about small-scale LCO2 generation on the web. We use the LCO2 for...
  50. B

    What is the derivation for the equation for liquid pressure at depth?

    The pressure of a liquid of constant density at depth 'h' is given by the equation: P = hρg I am trying to understand the derivation of this equation. I understand it perfectly for liquid columns with rectangular liquid columns but I can't see why it works if the shape of the fluid...
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