A string is wrapped around a uniform disk of mass M and radius R. Attached to the disk are four low-mass rods of radius b, each with a small mass in at the end (see figure below). m M M.R m The apparatus is initially at rest on a nearly frictionless surface. Then you pull the string with a constant force F. At the instant when the center of the disk has moved a distance d, an additional length w of string has unwound off the disk. (Use any variable or symbol stated above as necessary.) (a) At this instant, what is the speed of the center of the apparatus? You 2Fd 4m+M Explain your approach. I applied the Energy Principle to the system as a point particle. I applied the Energy Principle to the small masses only. I applied the Energy Principle to the system as an extended object (b) At this instant, what is the angular speed of the apparatus? @f Edit Explain your approach.