A piston 113 mm diameter and 150 mm long has a mass of 9 kg. It is placed in a vertical cylinder 115 diameter containing oil of dynamic viscosity 0.12 Pa · s and relative density 0.9 and it falls under its weight. Assuming that piston and cylinder are concentric, calculate the time taken for the piston to steadily through 75 mm

A torque is applied to rotate a cylindrical shaft (diameter D 1 , length L) at a constant angularspeed ω, inside a co-axial, stationary cylinder of the same length and diameter D 2. The gapbetween the bottom surface of the shaft and that of the stationary cylinder is h.(a) Develop a general expression of the torque in terms of the geometric dimensions andthe viscosity μ of an oil filling the gaps between the shaft and the stationary cylinder.Assume linear velocity profiles in all the gaps.(b) Determine the numerical value of the torque in the case of an oil of viscosity of 0.1Pa.s. [D 1=5cm, D 2=5.2cm, L=10cm, ω=50rpm, h=1mm]