(4) (a) In a micro-bearing configuration, a shaft of 1000 um diameter and 1 cm long rotates at 120 rpm inside a bearing housing of 1050 um diameter. Air occupies the gap between the shaft and bearing having mean free path, 1 = 2.5 um. Calculate the power consumed in overcoming friction for the above arrangement with both no-slip and slip flow boundary conditions assuming Couette flow between the gap. The viscosity of air j = 20 x 10-6 Pa-s; density, p = 1.23 kg/m and the momentum accommodation coefficient, on = 0.8. (b) Calculate the ratio of viscous dissipation for the slip flow boundary condition and the no- slip boundary condition and comment on the results. (4) (a) In a micro-bearing configuration, a shaft of 1000 um diameter and 1 cm long rotates at 120 rpm inside a bearing housing of 1050 um diameter. Air occupies the gap between the shaft and bearing having mean free path, 1 = 2.5 um. Calculate the power consumed in overcoming friction for the above arrangement with both no-slip and slip flow boundary conditions assuming Couette flow between the gap. The viscosity of air j = 20 x 10-6 Pa-s; density, p = 1.23 kg/m and the momentum accommodation coefficient, on = 0.8. (b) Calculate the ratio of viscous dissipation for the slip flow boundary condition and the no- slip boundary condition and comment on the results