In the arrangement shown, mass of block A is 1 kg and that of B is 4 kg. The pulleys are light. The system is released from rest. Then acceleration of B is

If ‘a’ be the downward acceleration of B, then upward acceleration of A will be ‘2a’. If T be the tension in the string connected to block A, then 2T will be the tension in the string connected to block B.For  block  A, T−1 × 10 = 1 × 2aFor block  B, 4 × 10 −2T = 4 × aSolving, a=2.5 m/s2