1. Rotating Disk Viscometer Problem 1.55 Jillann Walker 12.12.06

2. Abstract Given the rotating disk viscometer, determine the viscosity of the oil, and also determine the overall uncertainty in viscosity if each parameter ( M, R, h, f) is +/- 1percent.

3. Diagram

4. Known Values R = 5cm h = 1mm f = 900rpm τ = 0.537 Nm

5. Solve For V = Tangential Velocity -Used in viscosity formula μ = Viscosity

6. Assumptions Closed system Density is not relevant Shear stress is consistent throughout Velocity is linear

7. Equations Viscosity Tangential Velocity Note: V = Tangential Velocity Note: r = radius of disk

8. Solution = 2 x 3.14 x 0.05m x 15 = 4.71239

9. Explanation Shear takes place at the surface of the disk over the area. Higher velocity require lower viscosity Higher clearance requires higher viscosity 1 percent uncertainty –Largest uncertainty range at 1 on the top and -1 on the bottom of the plate –This is not a 2% difference

10. Biomedical Relation Shoulder joint or ankle joint. Refer to a ball and socket –The joint fitting will contain liquid of some sort and depending on the resistance needed to rotate the joint, will determine the viscosity of the liquid.

11. Questions?