4. Figure shows total \( (N \times 2) \) number of pulleys arranged to form a ring. Each is lower pulley is attached with masses \( m_{1}, m_{2}, m_{3} \ldots \ldots \ldots m_{N} \).
(a) If the system is released from given situation, find acceleration of mass \( m_{i} \).
(b) If \( m_{1}=m_{2}=m_{3}=\ldots \ldots . .=m_{N}=m \), and one of the blocks is pulled downwards by a force \( F_{0} \), then find acceleration of that block.
