106. . Many 2.5-in.-diameter(6.35-cm) computer hard disks spin at a constant 7200 rpm operating speed. The disks have a mass of about 7.50 g and are essentially uniform throughout with a very small hole at the center. If they reach their operating speed 2.50 s after being turned on, what average torque does the disk drive supply to the disk during the acceleration? Example 9-5