Viscosity PresentationViscosity PresentationByBy

Team EightTeam Eight

Objective Objective To determine how fluid a liquid really is by To determine how fluid a liquid really is by

measuring its viscosity. measuring its viscosity. We will simply see how fast a sphere falls We will simply see how fast a sphere falls

through a fluid. The faster the sphere falls, through a fluid. The faster the sphere falls, the lower the viscosity. The slower the the lower the viscosity. The slower the sphere falls, the higher the viscosity. sphere falls, the higher the viscosity.

Material List / Price ListMaterial List / Price ListMaterialsMaterials

Marbles (steel and glass) -$1.00Marbles (steel and glass) -$1.00Motor oil (10W-30) -$2.00 Motor oil (10W-30) -$2.00 Graduated cylinder -$5.00Graduated cylinder -$5.00Calculator-$15.00Calculator-$15.00 Stopwatch -$4.00Stopwatch -$4.00Ruler -$1.00Ruler -$1.00Thermometer-$15.00 Thermometer-$15.00

MethodMethod The measurement involves determining the velocity of the falling The measurement involves determining the velocity of the falling

sphere. This is accomplished by dropping each sphere through a sphere. This is accomplished by dropping each sphere through a measured distance of fluid and measuring how long it takes to measured distance of fluid and measuring how long it takes to traverse the distance. Thus, you know distance and time, so you traverse the distance. Thus, you know distance and time, so you also know velocity, which is distance/time. also know velocity, which is distance/time.

The formula for determining the viscosity is decorated with Greek The formula for determining the viscosity is decorated with Greek letters and a squared term, but simply amounts to multiplying some letters and a squared term, but simply amounts to multiplying some numbers and then dividing by some others: numbers and then dividing by some others:

delta p = difference in density between the sphere and the liquid delta p = difference in density between the sphere and the liquid g = acceleration of gravity g = acceleration of gravity a = radius of sphere a = radius of sphere v = velocity = d/t = (distance sphere falls)/(time of it takes to fall)v = velocity = d/t = (distance sphere falls)/(time of it takes to fall)

Fluid: Water Temperature:   °C   Fluid: Oil Temperature:   °C

Marble: Steel Radius:        m   Marble: Steel Radius:        m

Trial d (m) t (s) v (m/s) h(Pa s)   Trial d (m) t (s) v (m/s) h(Pa s)

1           1        

2           2        

3           3        

Fluid: Water Temperature:   °C   Fluid: Oil Temperature:   °C

Marble: Glass Radius:        m   Marble: Glass Radius:        m

Trial d (m) t (s) v (m/s) h(Pa s)   Trial d (m) t (s) v (m/s) h(Pa s)

1           1        

2           2        

3           3        

Type of Fluid  Water   Type of Fluid  Oil

Fluid density (p)     Fluid density (p)  

Density of sphere (p)     Density of sphere (p)  

Density Contrast     Density Contrast  

Radius of sphere (a)     Radius of sphere (a)  

Gravity (g) 9.8 m/s2   Gravity (g) 9.8 m/s2

Fall distance (d)     Fall distance (d)  

Data EntryData Entry

UsefulUseful TablesTables•g 9.8 m/s2 •Density for water 1000 kg/m3

•Steel marble density 8430 kg/m3

•Glass marble density 2850 kg/m3 •Density for 10W-30 881 kg/m3

 

Approximate Viscosities of Common Materials(At Room Temperature-70°F) *

Material Viscosity in Centipoise

Water 1 cps

SAE 30 Motor Oil 420-650 cps

SAE 40 Motor Oil 650-900 cps

Castrol Oil 1,000 cps

Karo Syrup 5,000 cps

Honey 10,000 cps

Chocolate 25,000 cps

Ketchup 50,000 cps

Peanut Butter 250,000 cps  

•100 Centipoise = 1 Poise 1 Centipoise = 1 mPa s (Millipascal Second)•1 Poise = 0.1 Pa s (Pascal Second)

Setup ModelSetup Model

ResourcesResources

•http://www.vp-scientific.com/Viscosity_Tables.htm

•http://www.spacegrant.hawaii.edu/class_acts/ViscosityTe.html

•http://www.nasaexplores.com/index.php

•Interactive Model

•Cornell University Model