$ \hat{\mathrm{j}} \mathrm{m} / \mathrm{s} $

$\overrightarrow{\mathrm{B}}  =2 \hat{\mathrm{k}} \mathrm{T} $
$\overrightarrow{\mathrm{F}}  =\mathrm{q}(\overrightarrow{\mathrm{v}} \times \overrightarrow{\mathrm{B}}) $
$ =4 \times 10^{-6}\left(4 \times 10^6 \hat{\mathrm{j}} \times 2 \hat{\mathrm{k}}\right) $
$ =4 \times 10^{-6} \times 8 \times 10^6 \hat{\mathrm{i}} $
$\overrightarrow{\mathrm{F}}  =32 \hat{\mathrm{i}} \mathrm{N} $
$\mathrm{x}  =32$