Halliday, Resnick & Walker — Force and Motion–I: Problem 50

In Fig. 5.29, three ballot boxes are connected by cords, one of which wraps over a pulley having negligible friction on its axle and negligible mass. The three masses are \( m_A = 30.0\text{ kg} \), \( m_B = 40.0\text{ kg} \), and \( m_C = 10.0\text{ kg} \). When the assembly is released from rest, (a) what is the tension in the cord connecting B and C, and (b) how far does A move in the first \( 0.250\text{ s} \) (assuming it does not reach the pulley)?