You push a $2.0 \mathrm{~kg}$ block against a horizontal spring, compressing the spring by $15 \mathrm{~cm}$. Then you release the block, and the spring sends it sliding across a tabletop. It stops $75 \mathrm{~cm}$ from where you released it. The spring constant is $200 \mathrm{~N} / \mathrm{m}$. What is the block-table coefficient of kinetic friction?