A solid uniform disk of mass 21.0 kg and radius 85.0 cm is at rest flat on a frictionless surface. A string is wrapped around the rim of the disk and a constant force of 35.0 N is applied to the string. The string does not slip on the rim. How much string has unwrapped from around the rim if the disk travels 7.3m?
The Attempt at a Solution
The amount of string unwrapped turns out to be 2x the distance traveled. I can't understand why this is so. (Conceptually) Does the disk not translate in the beginning while some amount of string is unwrapping? My gut intuition is the amount of string unwrapped equals the distance traveled by the disk. Can someone explain why this isn't so?