A block with mass $M$ rests on a frictionless surface and is connected to a horizontal spring of force constant $k$, the other end of which is attached to a wall (Figure 11.37 ). A second block with mass $m$ rests on top of the first block. The coefficient of static friction between the blocks is $\mu_{\mathrm{s}}$. Find the maximum amplitude of oscillation such that the top block will not slip on the bottom block.