Two blocks having mass $M_A=1kg$  and $M_B=4kg$  are connected by spring  and placed vertically on a weighing machine. Block A is held so that the spring is relaxed. At time t = 0 block A is released from this position and performs simple harmonic motion with angular frequency $\omega =25$  rad/s. The reading of weighing machine at time t is  ${\text{(g = 10 m/s}}^{\text{2}}\text{)}$