Each of the gears a and b has a mass of 675 g and has a radius of gyration of 40 mm, while gear c has a mass of 3.6 kg and a radius of gyration of 100 mm. assume that kinetic friction in the bearings of gears a, b, and c produces couples of constant magnitude 0.15 n·m, 0.15 n·m, and 0.3 n·m, respectively. knowing that the initial angular velocity of gear c is 2000 rpm, determine the time required for the system to come to rest.