\(40m\)

$$
\begin{aligned}
V&=u+a t \\
u&=0, v=8, t=4 \\
8&=0+4 a \\
\therefore\ & a=2 \\
v&=2 t \\
D_{1}&=\frac{1}{2} \times 4 \times 2 \times 4 \\
&=16 m\\
D_{2}&=\frac{1}{2} \times 6 \times 8 \\
&=24 \\ \text { Total distance } &=16+24 \\
&=40 \mathrm{~m}
\end{aligned}
$$