A string is wrapped around a disk of mass m = 1.9 kg and radius R = 0.12 m. Starting from rest, you pull the string with a constant force F = 8 N along a nearly frictionless surface. At the instant when the center of the disk has moved a distance x = 0.13 m, your hand has moved a distance of d = 0.26 m.
At this instant, what is the speed of the center of mass of the disk?
At this instant, how much rotational kinetic energy does the disk have relative to its center of mass?