You test a sample in a cup and bob viscometer to determine the viscosity. The diameter of the cup is $55 \mathrm{~mm}$, that of the bob is $50 \mathrm{~mm}$, and the length is $65 \mathrm{~mm}$. The cup is rotated and the torque on the bob is measured, giving the following data:

Cup Speed (rpm)	Torque on Bob (dyn cm)
2	3,000
10	6,000
20	11,800
30	14,500
40	17,800

(a) Determine the viscosity of this sample.

(b) How would you describe the viscosity of this material?

(c) What model would be the most appropriate to represent this viscosity?

(d) Determine the values of the parameters in the model that fit the model to the data.