$1-$ The angular acceleration of the disk is defined by $a=3t^2+12ra\frac{d}{s},$ where $t$ is in seconds. If the disk is originally rotating at $12ra\frac{d}{s},$ determine the magnitude of the velocity and then $n$ and $t$ components of acceleration of point $A$ on the disk when $t=2s.[$Answers: $22\frac{m}{s},12\frac{m}{s^2},968\frac{m}{s^2}]$