Viscosity Definition and 254 Threads

1. Hi there, We have some questions regarding the force it would take to keep a shaft moving in a tube at a constant velocity. I gather the formula we should use is: F/A=u*dux/dy My understanding is that in this formula F is the force required A is the parallel surface area u...

If helium 4, when it is a super fluid has no viscosity then you shouldn't be able to float anything in it. And if you had a column of it you could drop a piece of wood in it and it would fall at g just like it would fall a vacuum. Am i thinking about this correctly.

Fluids with a relatively high viscosity have a high resistance to flow. Fluids with a relatively low viscosity have very little resistance to flow. Kinematic viscosity is measured in mm2/s. (This is area per second.) If one "thick" oil and one "thin" oil are poured down onto a flat plane...

ive got two basic questions. 1: Does density effect viscosity, as in is it possible to have a highly dense but low viscosity fluid and vice versa. 2: I know in space there's no sound but can you hear your own heartbeat and other internal vibrations?

REWRITTEN: Well if you're interested I have a tank (actually a PVC tube with an end cap) that has an interior diameter of 86 mm. It stands on its circular face. Coming out near the bottom of the tank at a right angle is a metal pipe 11 mm in diameter (interior) and 312 mm long (in total that...

Hi all, i'm doing a research essay on how the viscosity of a fluid affects it's splashes. i'm currently stuck and do not know how i should approach this theoretically. i have no problem with the practical (filling up balloons with the fluid and dropping them from a height to see the splash...

When temperature increases, the resistance in a wire also increases. ( I = V/R ) However, when the temperature increases, viscosity (resistance in a fluid) decreases... These are both resistances. Why does temperature increase cause an opposing effect in them?

Hi, If the viscosity in the NS equations was a variable, what extra equation is used to solve the NS equations? Thanks.

Hi, I think I'm mixing things up... For a flow with low compressibility, I know density varies but does viscosity also vary? Does that depend on whether the flow is laminar or turbulent. Thanks, H

I have been looking into how the overall viscosity of a liquid/gas is related to kinematic and dynamic viscosities. I have used nwater = 1e-3 Pa.s nair = 17.4e-6 Pa.s densitywater = 1000 kgm^-3 densityair = 1.3 kgm^3 and kinematic viscosity v = n/density So vair ~ 1.4e-5 vwater ~...

My physics teacher is having us research random topics in advanced physics for us to get some experience with research. He assigned me Fluid Thread Viscosity, but I could not find any good sources on the web. Do you guys know of any good sites I could find some information on the topic? Thanks

Homework Statement A 0.75 sphere is dropped through a tall column of liquid. When the sphere has fallen a distance of 2.0 m, it is observed t have a velocity of 2.5 m/s. How much work was done by the frictional viscosity of the liquid? PLEASE EXPLAIN-- I really would like to understand this...

A uniform film of oil 0.13 mm thick separates two circular discs, each 150 mm diameter and mounted coaxially. Find the torque required to rotate one disc relative to the other at a steady speed of 400 rev/min if the oil has a viscosity of 0.14 Pa.s. (Ignore edge effects at the rim of the...

Homework Statement I have a fluid dynamics question and I am hoping maybe you can help me with it. I haven't taken a fluids course yet so I am at a loss as to the solution, and all of the books I've looked through have left me empty handed. For my Experimental project i decided to measure the...

does gravity effect viscosity ? is viscosity independent od gravity ?

I saw an example where the work of a heart was found to be 2 watts based on the height of a person and the liters of blood that it pumped throughout the day. Since we have closed circulation systems (unless we have a cut, annerism, etc. ) I thought height would not matter, and in order to...

Hi.everybody How do I derive viscosity equation F=6π*r*μ?

guys i am doing fluid mechanics for the first time at university level the textbook that was recommended by the lecturer is crap and the study guide only refers to the textbook please guys need your help with this question 3 N is needed to push a 50 mm diameter piston, 30 mm long slides...

Hi all, This is my first post and my background is in Computer Science, so pardon me if my terminology is not correct or even I sound ignorant Physics-wise :) Anyways, I implemented a semi-Lagrangian based Navier-Stokes (NS) solver and it's running smoothly on a CUDA-capable GPU and I...

Homework Statement I'm going to be doing an experiment to determine the viscosity of golden syrup by dropping different size steel ball bearings into a jar of golden syrup and recording how long it takes for them to travel a certain distance when there at terminal velocity. so from the...

Drag at high Reynolds numbers is given by the formula: 0.5*\rho*V2*Cd*A Why does at the molecular (or at the micro) level the drag is independent of the viscosity?

We are performing an experiment to determine the viscosity of water using the falling sphere method. I understand that the ratio of the radius of the sphere to the radius of the container has to be within a certain range in order to avoid a false high viscosity value. And a correction factor is...

Homework Statement We have a round disc with radius of 10 cm and mass of 1 kg, suspended on a wire and lying on a thin (1 mm) layer of oil. We torsionally nudge it and we get some info out of it: At angular velocity of 10 s^{-1} the amplitude is maximal. At angular velocity of 12 s^{-1}...

Can anyone tell me why this is true? I can't find an explanation anywhere, and it doesn't make sense to me geometrically either, especially for i=j. Isn't viscous force, by definition, a shear force? How can it produce a normal stress? Also why would Txy=Tyx? Why can't they be different...

Problem Statement A 50cm by 30cm by 20cm block weighing 150N is to be moved at a constant velocity of .8 m/s on an inclined surface with a friction coefficient of 0.27. (a) Determine the force f that needs to be applied in the horizontal direction. (b) if a .4mm thick oil film with a dynamic...

Homework Statement Does something like a viscosity constant of a cylinder exist? We are talking about an empty barrel rolling on a horisontal plane and the air friction. On the classes we got something like this c= 1.76h\cdot r where h is the barrel's height and r is the radius. How to find...

Hi, I'm performing some calculations and I need oil viscosity at 20°C. I have checked in some standards like SAE or ISO, but the lowest temperature I have found is 40°C. How may I extrapolate the viscosity a 20°C? Moreover I need a precise value of oil density, does someone know this value...

Hi, I am doing physics coursework on finding viscosity of fluids by dropping a marble into fluids, finding terminal velocity, then using stoke's law to find viscosity. (using density of fluid, sphere, sphere diameter etc). I have completed all the practical, now just the write up However ... I...

Homework Statement Help with the viscosity. The problem is in the attachment. My prof does not yet teach the lesson but we have to answer the problem. Homework Equations The Attempt at a Solution

hi all can someone explain me the units of Base oil viscosity of grease? for example is there a difference between grease rated at 200cSt and 200 mm2/s if so then what is the meaning of cSt and what does it stand for? thanks

I'm doing an essay for a Relativity course on the relativistic effects which would occur in daily life if the speed of light was somehow...lowered to a number such as 20m/s. My question is: "How would relativity affect motion though a liquid (such as swimming through a pool) at speeds such...

Homework Statement Two plane disks, each of radius 5cm, are mounted coaxially with their adjacent surfaces 1mm apart. They are in a chamber containing gas at STP (viscostiy of gas = 2.1 x 10^-5 Ns/m^2) and are free to rotate about the common acis. One of them rotates with angular velocity of...

Homework Statement A sphere of radius 1.06 cm is dropped into a glass cylinder filled with a viscous liquid. The mass of the sphere is 13.0 g and the density of the liquid is 1146 kg/m3. The sphere reaches a terminal speed of 0.166 m/s. What is the viscosity of the liquid? Variables (in...

if we use Poiseuille's equation, plotting the varying height of a water tank againts the rate of flow, does the gradient of the graph tell us the viscosity, or do we re-arrange the equation to find viscoisty. Thanks

Homework Statement A flat circular disc of radius 1.0m is rotated at an angular velocity of 0.65 rad/sec over a fixed flat surface. An oil film separates the disk and the surface. If the viscosity of the oil is 16 times that of water (20 degree C) and the space between the disk and the fixed...

Homework Statement A patient is to be given a blood transfusion through a tube from a raised bottle to a needle inserted in a vein. The needle has an inner diameter of 0.5mm and is 4.0cm long. If the required blood flow rate is 4.0cm^3/minute, how high should the bottle be placed above the...

I'm having a bit of trouble with some simple viscosity lab problem. The results are not of my own, so this could be some procedural error. We've used glycerol as the liquid medium at 3 different temperatures (0C, 10C, and 20C) with three different metal spheres, one of them being steel. All...

The question is attatched. The question is number 8. I simply do not understand, if the question is right at all, because I believe that options A and D are both correct. But, B it seems is the answer. High temp means low visc. and vice versa, leading to A and D being correct. Please...

Does the viscosity of air change with change in the degree of humidity at room temperature?

Calculating the viscosity of a 'test fluid' HELPPPPPPP! Can anyone please help me calculate the viscosity of each of the test fluids below. there are 5 of them and have each been tested 6 times. I am supposed to be doing straight line graphs and using the gradient to use to calculate the...

I have been doing a bit of research on building a low temperature Stirling engine, and I came across this website, http://heetgasmodelbouw.ridders.nu/Webpaginas/pagina_koffiekop_jan/koffiejan_frameset.htm The design on this website looks nice, and I would like to give it a go (after I build a...

In a question,I found a unit call 'viscosity',but i don't what it is can anyone explain the definition,I have no idea of this completely,THX

Hello all, I'm trying to nail down why the viscosity of air helps it bend around a curve. I have a specific, simplified example in mind to cut away other phenomena. Imagine the region immediately behind the camber of the top of a typical airfoil. That is, the place where the slope of the...

Hi everibody... I do not know is this question will be stupid... is there relation mathematical, phisics,etc..between wet ability and viscosity of one liquid type oil? Tanks and best regard

Homework Statement Hey, I am doing some work with torricellis equation and I have some questions. I am using the equation: dH/dt*A(h)=-B*squareroot(2*g*h) My question is, in my textbook it says the general formula is: dH/dt*A(h)=-0.6*B*squareroot(2*g*h) I want to know where the...

Fluids have viscosity, but do gasses have it? And in that case, what is the viscosity for normal air (I know air isn't one gas)?

How does the viscosity of a fluid in a circular can affect the way the can rolls? For example, 2 cans of similar size, volume, and mass are rolled down a ramp with the same slope. The can with a viscous liquid will take more force to begin rolling than a can with a less viscous liquid, but once...

How does the viscosity of a fluid in a circular can affect the way the can rolls? For example, 2 cans of similar size, volumn, and mass are rolled down a ramp with the same slope. The can with a viscous liquid will take more force to begin rolling than a can with a less viscous liquid, but once...

Hi, I'm looking for a little bit of help in this matter, I'm trying to put up a general formula of the internal force/volume in a fluid in a spot, as a function of how the velocity varies locally around that spot. What I started with was a formula I found in a book called "Physics Handbook...

An object rests on a high viscosity liquid like jelly what properties of the liquid keep it from breaking the surface of the jelly and sinking. (object deforms surface but doesn't break it) is it surface tension? Viscosity? How would the load carrying capacity of the jelly be tested?