On a banked race track, the smallest circular path on which cars can move has a radius of $100$ m $,$ while the largest has a radius of $159$ m $,$ as the drawing illustrates. The height of the outer wall is $10\mathrm{.}9$ m $.$ Find $($a$)$ the smallest and $($b$)$ the largest speed at which cars can move on this track without relying on friction.

$($a$)$ Number $$ Units $$

$($b$)$ Number $$ Units