What is Fluids: Definition and 518 Discussions

In physics, a fluid is a liquid or gas or other material that continually deforms (flows) under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear force applied to them.
Liquids form a free surface (that is, a surface not created by the container) while gases do not.
Although the term "fluid" generally includes both the liquid and gas phases, its definition varies among branches. Definition of "solid" vary as well, and depending on field, some substances can be both "fluid" and "solid". Viscoelastic fluids like Silly Putty appear to behave similar to a solid when a sudden force is applied. Also substances with a very high viscosity such as pitch appear to behave like a solid (see pitch drop experiment). In particle physics, the concept is extended to include fluidic matters other than liquids or gases. "Fluid" in medicine and biology specifically means any liquid constituent of the body (body fluid), whereas "liquid" is not used in this sense. Sometimes liquids to be taken for fluid replacement, either by drinking or by injection, are also called "fluid" ("drink plenty of fluids"). In hydraulics, "fluid" is a term which refers to liquids of certain properties, and is a broader concept than "(hydraulic) oils".

View More On Wikipedia.org
Recent contents Top users
  1. K

    What is the fraction of an iceberg's volume exposed in seawater?

    Homework Statement The density of ice is 920 kg/m3, and that of seawater is 1030 kg/m3. What fraction of the total volume of an iceburg is exposed? Homework Equations The Attempt at a Solution I know your supposed to do volume of the ice divided by the volume of the seawater, x...
  2. K

    Gauge pressure and fluids problem

    [b]1. Homework Statement [/b An automobile tire having a temperature of .64 degrees C is filled to a gauge pressure of 27 lb ft/in2. What would be the gauge pressure in the tire when its temperature rises to 39 degrees C? Homework Equations Assume the volume remains constant, the air...
  3. K

    Maximum Safe Depth Calculation for a Submarine with a Thick Window

    Homework Statement A research submarine has a 10.0 -diameter window 8.90 thick. The manufacturer says the window can withstand forces up to 1.10×10^6 . What is the submarine's maximum safe depth? The pressure inside the submarine is maintained at 1.0 atm. Homework Equations p=F/A...
  4. R

    What Gauge Pressure is Needed for a Water Jet to Reach 29.8 m/s?

    Help! Physics Fluids problem Homework Statement Water is forced out of a fire extinguisher by air pressure. How much gauge air pressure in the tank (above atmospheric) is required for the water jet to have a speed of 29.8 m/s when the water level is d=0.515 m below the nozzle? Homework...
  5. K

    Estimate Air Speed Above Plane Wings: Bernouli Eqn

    An airplane flies on a level path. There is a pressure difference of 540 Pa between the lower and upper surfaces of the wings. The area of each wing surface is about 150 m^2. The air moves below the wings at a speed of 81.0 m/s. (a) Estimate the weight of the plane. (b) Estimate the air speed...
  6. M

    Change in pressure with fluids

    A garden hose with a diameter of 0.66 in has water flowing in it with a speed of 0.65 m/s and a pressure of 1.0 atmospheres. At the end of the hose is a nozzle with a diameter of 0.25 in. (a) Find the speed of water in the nozzle. (b) Find the pressure in the nozzle. I found out the speed...
  7. M

    How Do Piston Sizes Affect Height Differences in Hydraulic Systems?

    In a hydraulic system the piston on the left has a diameter of 4.7 cm and a mass of 1.7 kg. The piston on the right has a diameter of 12 cm and a mass of 3.7 kg. If the density of the fluid is 750 kg/m3, what is the height difference h between the two pistons? I'm not even sure what equation...
  8. M

    Solving U-Tube Fluid Problem: h1 Calculation

    The problem is; “Mercury is poured into a U-tube. The left arm of the tube has cross-sectional area A1 of 10.0cm^2, and the right arm has a cross-sectional area A2 of 5.0cm^2. 100 grams of water are then poured into the right arm. (a) Determine the length of the water column in the right...
  9. M

    Calculating the Radius of a Floating Aluminum Ball | Fluids Question

    My Question is " A spherical aluminum ball of mass 1.26kg contains an empty spherical cavity that is concentric with the ball. The ball just barely floats in water. Calculate (a) the outer radius of the ball and (b) the radius of the cavity." I'm notsure if it's right, but so far I have...
  10. D

    Question about momentum transfer from fluids to discrete particles

    Hi, I am having trouble find information on the following topic, I think mostly in part because I don't know the correct terminology. Basically, I have a number of particles that are falling at their terminal velocities within a gaseous fluid, and turbulent velocity fluctuations in the fluid...
  11. F

    Fluids bernoulli's equation problem

    Water flows throgh a horizontal tube of diameter 2.8cm that is joined to a second horizontal tube of diameter 1.6cm. the pressure difference between the tubes is 7.5kPa. which tube has the higher pressure flow? which tube has the higher speed flow? find the speed of flow in the first tube...
  12. F

    Calculating Hydrostatic and Gravitational Forces in Fluid Mechanics

    In Figure 14-31, an open tube of length L = 1.8 m and cross-sectional area A = 4.6 cm2 is fixed to the top of a cylindrical barrel of diameter D = 1.2 m and height H = 1.8 m. The barrel and tube are filled with water (to the top of the tube). Calculate the ratio of the hydrostatic force on the...
  13. T

    Fluids mechanics Helium balloon

    A spherical helium balloon is 2.5 m in diameter and has a total mass of 6.7 kg. When released into the U. S. Standard Atmosphere, at what altitude will it settle? My first thought was that diagram has the weight of the balloon acting downward, buoyant force upwards. -weight + Fb = 0...
  14. F

    Faster fluids have a lower pressure?

    I'm doing an assignment on helicopter flight, and I'm a little confused about the Bernoulli principle. He said that if a pipe is bigger at the beginning and smaller at the end, the fluid traveling through the end of the pipe would have a lower pressure. This seems counter-intuitive. I would...
  15. T

    Help - Explain physics of fluids

    Hi everyone, I need some help from some of you for a little research I am doing. I am trying to figure out the Physics of Fluid running down a uneven surface, like water running down the windshield of your car. Seemingly random and yes with a degree of randomness but also with a degree...
  16. F

    Fluids - variation of velocity for free jets

    hey guys, only my second post here, hope these boards are helpful! I have a problem for my fluid mechanics class and was wondering if anyone could help me out. i will post the question and the figures and what assumptions i have made due to the lack of information. Several holes are...
  17. I

    Pressure Drop in Moving Fluids

    Lets say water was rising vertically up a pipe at a lower pressure and lower velocity. Is the pressure drop the same in faster and slower moving fluids or does slower moving fluid lose less pressure from pressure drop.
  18. P

    Mechanics of Fluids Third Edition, Potter and Wiggert

    Currently using this book on my undergraduate mechanical engineering course, does anyone have a full list of solutions for the book as they only print selected solutions in the back? This would be very helpful for me for checking my work whilst revising for my dreaded resit! Thanks Phil
  19. T

    Thermo & Fluids: Student Experiences & Advice

    Hi all. I've heard from students that Thermodynamics and Fluids are really tough classes. I've taken all the physics and the calculus with no problems. What do you guys think about those classes?
  20. B

    Cant find an appropriate fluids equation

    Hi guys this is my first post on here, and I like the look of it so far. I've tried to look everywhere for an approprate equation for this question but I can't come up with one, or maybe I am overlooking something. What is the minimum power (W) required to pump blood in the human body...
  21. Z

    How can you use pressure to rescue a friend who has fallen through ice?

    Hey guys my first homework question I'll be asking here... as simple as it may sound this question is kinda stupid and pissed me off so here goes... Your friend has fallen through the ice and you decide to attempt a rescue. Having just come from a physics class on pressure, how will you do...
  22. S

    Power of Water Pump: Calculating Flow & Velocity

    Hi. I am having a little difficulty finding the power in this question. It is energy divided by time right? Any help would be appreciated: Water is pumped steadily out of a flooded basement at a speed of 5.0 m/s through a uniform hose of radius 1.0 cm. The hose passes out a window 3.0 m...
  23. U

    Super fluids and pauli exclusion principle

    I don't understand how can atoms like heilium-4 which has same amounts of fermions behave like bosons and do not obey pauli's exclusion principle. Do the heilium physically stack up together like laser light, or does it just seem to do that? could someone please explain how superfluids work.
  24. A

    Work, Energy, Fluids, Temperature, and Kinetic Theory

    Okay, I need help on a lot questions. I most of the math parts, but this stuff just completely confuses me. Any help will be greatly appreciated. Please help me not fail my class. Work/Energy Two identical arrows, one with twice the speed of the other, are fired into a bale of hay. Assuming...
  25. C

    Finding Max Leak Rate to Maintain Pressure in Pressure Vessel

    Well, simple may be relative. I've got a question that I'm looking for a simple equation for. Maybe someone can help me out... here it is; You have a pressure vessel with known volume that you want to keep at a known positive pressure (if it helps, assume that the atmosphere is at vacuum)...
  26. M

    Calculating Frictional Force in a Water Eroded Tube: A Case Study

    This one is a doozy . . . A fresh water pond that is 15.7 m deep is contained on one side by a cliff. The water has eroded a nearly horizontal "tube" through a bed of limestone, which allows the water to emerge on the other side of the cliff. If the "tube" has a diameter of 4.05 cm, and is...
  27. A

    Fluids - bringing together pressure, depth and friction

    Fluids -- bringing together pressure, depth and friction Hi Again! More troubles with fluids. I was pretty sure I had this one. There is a freshwater pond density, D=1000 kg/m^3 depth = 15.1 m one of the sides is blocked off by a cliff. A nearly horizontal tube diameter =...
  28. A

    How Is the Force Distributed in an Evacuated Chamber with a Panel Cover?

    Fluids -- evacuated chambers I've worked on this problem in a few different ways. Maybe I'm having trouble with the direction of my forces: We have a an evacuated chamber the pressure inside of the chamber is 23.0 kPa a 5cm diameter hole covered by a 0.225m diameter circular panel...
  29. S

    Fluids - I wish the answer would flow to me

    Fluids - I wish the answer would "flow" to me I have two problems to do and I seem to suck at fluids...:-p . The drawing shows a hydraulic system used with disc brakes. The force F is applied perpendicularly to the brake pedal. The brake pedal rotates about the axis shown in the drawing and...
  30. J

    Solving for Car Mass with Gauge Pressure and Surface Area | Physics Problems

    Fluid Problems 1) The gauge pressure in each of the four tires of a car is 240kPa. If each tire has a "footprint" of 220cm^2, estimate the mass of the car. answer: 2.2 x 10^3 kg pressure = 240 kPa, Area = 2.2 x 10^3 kg The first thing I assume i need to do is convert kPa but I have not...
  31. A

    Fluids Problem: Calculating Oil Layer Depth for Floating Soap Bar

    A 2cm thick bar of soap is floating on a water surface so that 1.5cm of the bar is underwater. Bath oil of specific gravity 0.60 is poured into the water and floats on top of the water. What is the depth of the oil layer when the top of the soap is just level with the uper surface of the oil?
  32. T

    Determine Length of Water & Height of Mercury Rise in U-Tube

    Mercury is poured into a u-tube. The left arm has cross sectional area A1 = 10 cm^2, the right has area A2, 5cm^2. 100 g of water are then poured into the right arm. determine the length of the water in the right arm and given the density of Hg = 13.6 g/cm^3, what distance h, does the...
  33. R

    Application of Bernoulli's Equation Physics question on FLUIDS unit

    A large root beer keg of height H and cross sectional area A1 is filled with root beer. The top is open to atmospheric pressure. At the bottom is a spigot opening of area A2, which is much smaller than A1. Find the total time needed to drain the keg if H=2m, A1=.8m^2 and A2=10^-4 * A1.
  34. Greg Bernhardt

    Dr. Donald Luttermoser: Solids & Fluids

    Author: Dr. Donald Luttermoser of East Tennessee State University
  35. D

    Understanding the Effects of Stirring vs. Rotating Fluids: A Physics Discussion

    Hello, An item in Jearl Walker's "The Flying Circus of Physics" discusses stirring tea. (4.63) I understand that stirring causes the fluid to move faster toward the center thus producing lower pressure near the center. Higher pressure exists at the wall and this pressure difference causes the...
  36. 2

    What Is the Force on a Square Roof During High Winds with Bernoulli's Equation?

    During high winds, the atmospheric pressure inside a house may blow off the roof because of the reduced pressure outside. Calculate the force on a square roof of side 22.0 m if the wind speed over the roof is 29.0 i used bernoulli's equation and got an answer of... 246356N i used 1.21 as...
  37. C

    Stargate Atlantis/ pressure and fluids

    Hi, This isn't exactly a homework question, but it is about what I once did in class and about something I was thinking about while I was watching tv (hey I'm thinking about physics in my spare time!o:)). If you watch stargate atlantis, you'll know that they can create a gate in one place...
  38. N

    Fluids - floating balloon problem

    Hi - I know this must be a basic question, but I'm doing this physics problem and I can't get the exact answer! Here it is and my work along with it - can someone please tell me what I'm missing in my equations? The problem is taken from the James Walker physics book - Chapter 15. Number...
  39. O

    Fluids Homework Help: Pascal's Barrel Burst Problem

    help in working out his principal,pascal showed dramatically how force can be multiplied with fluid pressure.he placed a long thin tube of 0.30cm radious vertically into a 20cm radious wine barrel.He found that when the barrel was filled with water and the tube filled to a height of 12m.the...
  40. P

    Understanding Fluid Pressure: How Deep Can a Snorkeler Safely Dive?

    human lung can withstand an inside/outside difference of about .06 atm. if a diver is using a snorkel to breathe, how far below the water surface can he get before he is risking lung damage? pressure of outside is the water pressure at that depth, while pressure inside is the pressure of the...
  41. S

    Specific Heats for Incompressible Fluids

    Given the following equation: Cp = Cv + R Where Cp is specific heat (constant pressure), Cv is specific heat (constant volume), and R is the universal gas constant. However, my book states that for an incompressible fluid, Cp = Cv. How can this be the case given the above equation...
  42. C

    Pressure in Fluids: Conceptual Q & Maths Explained

    I have a conceptual question about fluid... we derive the equations about pressure in fluid by considering the mass above a particular point in fluid. and for fluid at rest, the pressure above equals pressure from below. how about on the perpendicular plane? is the pressure on the sides equal...
  43. C

    Pressure in Fluids: Derivation & Explanation

    Pressure in fluids... I have been looking at derivation of the equation Pressure in fluids= height of fluid column*density*gravitational field strength, from the intitial starting point of P = F/A and taking F to be weight of column. But I have since read that the pressure is not in fact due to...
  44. A

    Fluids: calculate pressure loss due to turns in pipe flow

    Hi, I am trying to estimate the flow rate in a long pipe of rectangular cross section. The pipe is 100 m long and has twenty 180 degree turns. I have been able to calculate the pressure drip for a 100m straight pipe, but I have not been able to estimate the losses due to the turns. Is there...
  45. R

    Fluids and buoyance, determine how much of the cylinder is in the oil

    I have two physics problems on fluids that I'm stuck on and would appreciate any help! This is an algebra based physics class... (no calculus). 1. A solid cylinder (radius = 0.150 m, height = 0.120 m) has a mass of 7.00 kg. This cylinder is floating in water. Then oil (rho = 725 kg/m^3)...
  46. S

    How Deep Could Tarzan Dive While Breathing Through a Reed?

    Ape Man in a movie is shown evading his captors by hiding underwater for many minutes while breathing through a long reed. Assuming the maximum pressure difference lungs can manage and still breathe is -80 mm-Hg , calculate the deepest he could have been. I immediately thought of P = p*g*h...
  47. A

    How do Electrorheological fluids work?

    ive been reading up a little bit, (a very little bit actually, i have really bad science info sources lol) about electrorheological fluids, now as i understand it, these fluids increse in viscosity as voltage increses. doesn't this meen taht density or mass should increece also? couldn't that...
  48. A

    What is the density of the life preserver?

    This one got me. Any help? Regardless of if its being homework, respond if you can. A life preserver with a volume of .05m^3 will support a 80kg person with a specific gravity of .92, in seawater, specific gravity of 1.03, the person is 20% above water(volume-wise) and the preserver is...
  49. S

    Find the Density of an Object Immersed in Water & Oil: 32.142857kg/5.612246m3

    An object weighing 315 N in air is immersed in water after being tied to a string connected to a balance. The scale now reads 260 N. Immersed in oil, the object weighs 275 N. Find the density of the object in kg/m3. I found the mass of the object to be 32.142857kg and the apparent mass when...
  50. F

    How Does Pipe Width Affect Water Flow and Speed?

    Every second, 1.2 cubic meters of water enters a heating system through a pipe of medium width, A, with a cross sectional area of .2 meters squared. The water then flows into a wide pipe, B, with an area of .6 meters squared, and flows out through a narrow peipe, C, with an area of .1 meters...
Back
Top