Answer
$1.4$
Work Step by Step
We can find the coefficient of kinetic friction as follows:
$\Sigma F_x=F_{spring}-f_k=0$
$\implies Kx-\mu_kN=0$
This can be rearranged as:
$\mu_k=\frac{Kx}{N}$
$\implies \mu_k=\frac{Kx}{mg}$
We plug in the known values to obtain:
$\mu_k=\frac{(850.0)(0.0620)}{(3.85)(9.81)}$
$\mu_k=1.4$
