Question 12 of 308

A particle is moving in one dimension (along $x$ axis) under the action of a variable force. It's initial position was $16m$ right of origin. The variation of its position $\left(x\right)$ with time $\left(t\right)$ is given as $x=–3{t}^{3}+18{t}^{2}+16t,$ where $x$ is in $m$ and $t$ is in $s.$ The velocity of the particle when its acceleration becomes zero is _________ $m{s}^{-1}.$