Question $1(50\%)$: Microscopes with high focus, some electronic drives, and other instruments

having angular motion are damped by means of a disk connected to a shaft. The disk $($black$),$ in turn,

is immersed in a container of oil $($light grey$),$ as shown. The oil forms a film of thickness S on both

sides of the disk, dragging against the disk's rotation thus damping its motion.

aT$\_($drag $)$ D$,$ spacing S$,$

rate of rotation $\backslash$omega $,$ and oil viscosity $\backslash$mu $.$

bD$=50$mm$,$S$=1$mm$,\backslash$mu $=0\mathrm{.}125$Pa$*$s to keep the shaft rotating

at a constant angular velocity $\backslash$omega $=5000$rpm $($rpm $-$ revolutions per minute$)?$