posted by Sam .
In the figure below, three ballot boxes are connected by cords, one of which wraps over a pulley having negligible friction on its axle and negligible mass. The masses are mA = 30.0 kg, mB = 40.0 kg, mC = 28.0 kg.
The image is a horizontal pulley, with mass mA on the left, and B and C on the right side, underneath the pulley and connected by a rope.
(a) When the assembly is released from rest, what is the tension in the cord that connects boxes B and C?
(b) How far does box A move in the first 0.250 s (assuming it does not reach the pulley)?