Which of the following statements are associated with complete dynamic balancing of rotating systems? 1. Resultant couple due to all inertia forces is zero. 2. Support reactions due to forces are zero but not due to couples. 3. The system is automatically statically balanced. 4. Centre of masses of the system lies on the axis of rotation.
(a) 1, 2, 3 and 4 (b) 1, 2, and 3 only
(c) 2, 3 and 4 only (d) 1, 3 and 4 only