A block of mass m=1.25 kg sliding along a rough horizontal surface is traveling at a speed v₁ =2.0 m/s when it strikes a massless spring head-on (see figure) and compresses the spring a maximum distance X. If the spring has stiffness constant k=300 N/m, determine the coefficient of kinetic friction between block and surface. [25 p] m (a) k FS Fy k m (b)