(b) A grindstone in the shape of a solid disk with diameter 0.520 m and a mass of 50.0 kg is rotating at 850 rev/min. You press an axe against the rim with a normal force of 160 N (see below), and the grindstone comes to rest in 7.50 s. Find the coefficient of kinetic friction be- tween the axe and the grindstone. There is negligible friction in the bearings. m = 50.0 kg F = 160 N

(b) A grindstone in the shape of a solid disk with diameter 0.520 m and a mass of 50.0 kg is rotating at 850 rev/min. You press an axe against the rim with a normal force of 160 N (see below), and the grindstone comes to rest in 7.50 s. Find the coefficient of kinetic friction be- tween the axe and the grindstone. There is negligible friction in the bearings. m = 50.0 kg F = 160 N