$16\mathrm{.}98$ through $16\mathrm{.}101$ A drum of $80-mm$ radius is attached to a disk of $160-mm$ radius. The disk and drum have a combined mass of $5$ kg and a combined radius of gyration of $120$ mm $.$ A cord is attached as shown and pulled with a force $P$ of magnitude $20$ N $.$ Knowing that the coefficients of static and kinetic friction are ${}_s=0\mathrm{.}25$ and ${}_k=0\mathrm{.}2,$ respectively, determine $($a$)$ whether or not the disk slides, $($b$)$ the angular acceleration of the disk, $($c$)$ the acceleration of $G.$