A block of mass M rests on a frictionless surface and is connected to a horizontal spring of constant k. The other end of the spring is attached to a wall. A second block of mass m rests on top of the first block. The coefficient of static friction between the two blocks is . What is the maximum acceleration of the system such that the top block will not slip on the bottom block? What is the maximum amplitude of oscillation such that the top block will not slip on the bottom block?