The arrangement shown in the diagram is moving in space with an acceleration a=4(hati+hatj)m//s^(2). An ideal spring of natural length l_(0) having spring constant k=50 N//m, is connected to block A. Blocks A and B are connected by an ideal string passing through a frictionless pulley. Mass of each block A and B is equal to m=2kg. (a) Calculate the minimum value of coefficient of friction so that spring remains in its natural length. (b) If mu is reduced to (9//35)^(th) of the original value, calculate the maximum extension of the spring.