Answer
$E = (-0.600~N/C)~\hat{k}$
Work Step by Step
The magnetic field is in the +y direction.
By the right hand rule, as the solid moves in the +x direction, there is a force on the electrons that pushes them in the -z direction.
The potential difference is $V = vBd_z$
We can find the electric field:
$V = vBd_z$
$\frac{V}{d_z} = vB$
$E = vB$
$E = (20.0~m/s)(30.0~mT)$
$E = (-0.600~N/C)~\hat{k}$
