A 2.00 -kg block situated on a rough incline is connected to a spring of negligible mass having a spring constant of 100 $\mathrm{N} / \mathrm{m}$ (Fig. P8.54). The pulley is frictionless. The block is released from rest when the spring is unstretched. The block moves 20.0 $\mathrm{cm}$ down the incline before coming to rest. Find the coefficient of kinetic friction between block and incline.