Answer
using $v^{2}=v_{0}^{2}+2 a \Delta x,$ we find
$$
a=\frac{(7000 \mathrm{m} / \mathrm{s})^{2}}{2(3500 \mathrm{m})}=7000 \mathrm{m} / \mathrm{s}^{2}=714 \mathrm{g}
$$
Work Step by Step
using $v^{2}=v_{0}^{2}+2 a \Delta x,$ we find
$$
a=\frac{(7000 \mathrm{m} / \mathrm{s})^{2}}{2(3500 \mathrm{m})}=7000 \mathrm{m} / \mathrm{s}^{2}=714 \mathrm{g}
$$
