- #1
RoryScanlan
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Homework Statement
I have been given an experiment to perform, whereby I drop steel ball bearings into a glass measuring cylinder, and time how long it takes for the ball bearing to fall a set distance.
From this I should be able to work out the viscosity coeffienct of the glycerol.
I have been given this sum to work with:
[itex]2g/9(p-o)r^2/v [/itex]
Whereby :
p = the density of the ball bearing
o = the density of the glycerol(given to me as 1260kg/m3
r = radius of sphere
v = average velocity
I have crunched some number but I think they represent the reistants the sphere feels in the fluid, not the actual viscosity of the fluid. This is because the number I am receiving from the sum is raising in line with the radius of the sphere. If this is the case how to can i make the connection between this ristance and the coeffient viscosity of the fluid?
This is not a physics course and I do not study physics so if u can try to keep it simple it would be nice :)
Any links or help would be greeat!
Homework Equations
The Attempt at a Solution
Here is one of my test, does the final number represent the viscosity coeffient of the fluid or does it represent the resistance the object feels? or does it represent nothing? :P
Ball Bearing: 4mm. Mass: 0.00026kg. Distance traveled 0.20m.
Radius (m) : Diametre(mm)/2 = 4/2 = 2 ÷1000 = 0.002
Volume (m3) : V= 4/3 πr3 = 4/3 ∙ 3.141592 ∙ 23 = 33.51031469 ×〖10〗^(-9) = 3.351031469 × 〖10〗^(-8)
Density (kg/m3) : Mass/Volume = 0.00026/(3.351031469 × 〖10〗^(-8) ) = 7758.805085
Time Taken Test 1 (s) : 4.65
Time Taken Test 2 (s) : 4.80
Time Taken Test 3 (s) : 4.79
Average Time (s) : 4.75
Average Velocity (m/s) 0.20/4.75=0.04
Viscosity Coefficient of glycerol according to this test: Viscosity = 2(g/9) × (∆P) × (r^2/v)=
2(9.81/9) × (7758.81-1260) × (〖0.002〗^2/0.04) = 1.41675584
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