A uniform disk of mass M = 12.0 kg and radius R = 0.75 m is free to rotate about a frictionless axle during its center. A cord wrapped around the rim of the disk and is pulled with a steady tension of 100 N. As the cord is unwound the disk rotates. If the disk starts from rest:
a. Evaluate the angular velocity after 6.0 seconds.
b. Evaluate the total angular displacement.