Finding the coefficient of viscosity

AI Thread Summary
To find the coefficient of viscosity, the gradient of the line must be calculated using the change in y over the change in x. One participant calculated a slope of 0.34 based on provided measurements, while another suggested that the slope could also be justified by using a linear equation with an intercept. The discussion highlights the importance of plotting the data to verify the linearity of the relationship between variables. Concerns were raised about whether static friction was accounted for in the calculations. Ultimately, the correct approach to calculating viscosity depends on accurately determining the slope and understanding the experimental setup.
joshm12
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Homework Statement
How do I work out the coefficient of viscosity when the slope of a graph =0.34
n= coefficient of viscosity
v=speed of rotation
f= force required to maintain speed
Relevant Equations
F=1.67nv
"Calculate the gradient (or slope) of the line and use this and the equation above to calculate the value for the viscosity, η. You MUST use the gradient to calculate the viscosity." here are the results:

1595948993163.png


I'm not sure if it's just me who finds this confusing
 
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Hello @joshm12, :welcome: !

What did you find for the slope of the line ? And how did you do that ? By forcing an intercept 0 ?
Did you make a plot to see if that is justified ?

Are these your own measurements or were they given as part of the problem statement ?
 
@BvU I used the change in y/change in x to find the slope of the line and got 0.34. and the measurements were given as part of the problem
 
Last edited:
joshm12 said:
I used the change in y/change in x
Yes, I know that. How did you do it ?
 
This is for flow between a rotating cylinder and a stationary cylinder. Is the gap between the cylinders small?
 
BvU said:
What did you find for the slope of the line ? And how did you do that ? By forcing an intercept 0 ?
Did you make a plot to see if that is justified ?
 
I think @joshm12 didn't bother: he wasn't seen after #3.

The data don't exclude static friction, so ax+b seems equally justified and gives a slope 0.3

1596486928215.png
 
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