일반물리학 1 — Rotation: Problem 49

49 A cord with negligible mass is wrapped around a pulley that is a uniform disk of mass 5.00 kg and radius 0.300 m and that can rotate without friction about its central axis. A 1.0 kg bucket is attached at the free end of the cord hanging down from the pulley and then released at time \( t = 0 \). The cord begins to unwrap from the pulley as the bucket descends. At \( t = 5.00 \) s, through how many rotations has the pulley turned (the bucket is still descending)?