Answer
$\frac{\Delta T}{\Delta t}=0.217\frac{K}{s}$
Work Step by Step
We know that;
$v=\alpha L_{\circ}\frac{\Delta T}{\Delta t}$
This is rearranged as;
$\frac{\Delta T}{\Delta t}=\frac{v}{\alpha L_{\circ}}$
We plug in the known values to obtain:
$\frac{\Delta T}{\Delta t}=\frac{100\times 10^{-9}}{23\times 10^{-6}(0.02)}=0.217\frac{K}{s}$
