Answer
$v = 38.2~cm/s$
Work Step by Step
We can write an expression for the potential difference when a strip moves in a magnetic field at speed $v$:
$V = vBd$
We can use this expression to find $v$:
$V = vBd$
$v = \frac{V}{Bd}$
$v = \frac{3.90\times 10^{-6}~V}{(1.20\times 10^{-3}~T)(8.5\times 10^{-3}~m)}$
$v = 0.382~m/s$
$v = 38.2~cm/s$
