An elevator is moving vertically upward with an acceleration $a_0=4m/s^2.$ A man of mass M = 60 kg is standing on a massless weighing machine which is kept on a platform of mass m = 10 kg. Platform is connected with a spring as shown in the figure. Platform oscillates with a frequency of $0.5{\sec }^{-1}$ and amplitude 0.2 m. $N_0$ is the maximum reading of the weighing machine in kilogram and $x_0$ is the additional compression (in meter) in the spring from equilibrium position when the reading was 90kg. (Take ${\pi }^2=10,g=10m/s^2$ )