\(S =2 t ^3\) given
\(\frac{d s}{d t}=6 t^2 \Rightarrow v=6 t^2\)
At \(t =2 s \quad v =24 m / s\)
Centripetal acc. \(=\frac{ v ^2}{ R }=\frac{24 \times 24}{12}=48\)
\(\frac{ d ^2 s }{ dt ^2}= a _{ t }=\) Tangential acc. \(=12 t\)
\(\operatorname{At} t=2 \sec \quad a_t=24\)
\(\therefore \frac{a_t}{a_c}=\frac{24}{48}=1: 2\)