co A puck of mass $m=1.50 \mathrm{~kg}$ slides in a circle of radius $r=20.0 \mathrm{~cm}$ on a frictionless table while attached to a hanging cylinder of mass $M=2.50 \mathrm{~kg}$ by means of a cord that extends through a hole in the table (Fig. 6-43). What speed keeps the cylinder at rest?