A uniform solid disk of mass
m=1 kg and radius
r rests on top of a horizontal platform of mass
M=4 kg. The disk is connected by a horizontal spring of constant
k=600 N/m to a rigid post fixed to the platform; the spring lies in the plane of the disk. There is sufficient friction between the disk and platform for rolling without slipping, but the coefficient of static friction between the platform and the ground is only
μ=0.1. The disk is placed at the spring's natural length and given a horizontal velocity
v, rolling without slipping from the start. For what
v will the platform never slip on the ground? Use
g=10 m/s2.