A child on a swing set swings back and forth. The length of the supporting cables for the swing is

$=4\mathrm{.}9$m$.$

a$)$ what is the period of oscillation? $[6$pt$.]$

b$)$ If the child has a mass of m $=32\mathrm{.}0$kg$,$ and the swing is initially displaced $=15\mathrm{.}0$ from the virtical,

what is the child$$s velocity at the bottom of the swing? $[6$pt$.]$