A 10 lb block is attached to an unstretched spring of constant k = 12 lb/in. The coefficient of static and kinetic friction between the block and the plane are 0.6 and 0.4 respectively. if a force is slowly applied to the block until the tension in the spring reaches 20 lb and then suddenly removed, determine
a.) The velocity of the block as it return to its initial position
b.) The maximum velocity achieved by the block.