Problem $2$: A small block of mass $M=982g$ is placed on top of a larger block of mass $3$ M which is placed on a level frictionless surface and is attached to a horizontal spring of spring constant $k=3\mathrm{.}89\frac{N}{m}.$ The coefficient of static friction between the blocks is $=0\mathrm{.}20.$ The lower block is pulled until the attached spring is stretched a distance $D=8\mathrm{.}91cm$ and released.