A block of mass `4 kg` attached with spring of spring constant `100 N//m` is executing `SHM` of amplitude `0.1 m` on smooth horizontal surface as shown in figure. If another block of mass `5 kg` is gently placed on it, at the instant it passes through the mean position and new amplitude of motion is `n^(-1)` meter then find `n`. Assuming that two blocks always mvoe together .
