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.