A block of mass m = 0.51 kg attached to a spring with force constant 119 N/m is free to move on a frictionless, horizontal surface as in the figure below. The block is released from rest after the spring is stretched a distance A = 0.13 m. (Indicate the direction with the sign of your answer. Assume that the positive direction is to the right.) m A (a) At that instant, find the force on the block. N (b) At that instant, find its acceleration. m/s2