A point P moves in counter-clockwise direction on a circular path as shown in the figure. The movement of $'P'$ is such that it sweeps out a length $s = t^3 +5$, where $s$ is metres and $t$ is in seconds. The radius of the path is $20 \;m$. The acceleration of $'P'$ when $t = 2\;s$ is nearly <br>