1. The velocity, $vm{s}^{-1}$, of a particle moving in a straight line at time $t$ seconds can be found using the following expressions

$v=\{\begin{matrix}(t-4)(t+1)0\leqt\leq6\\14t\geq6\end{matrix}\}\;$

(i) Find the initial speed of the particle.

(ii) Write down the acceleration for $t\geq6$.