A $1 \mathrm{~kg}$ mass is attached to a spring of force constant $600 \mathrm{~N} / \mathrm{m}$ and rests on a smooth horizontal surface with other end of the spring tied to wall as shown in figure. A second mass of $0.5 \mathrm{~kg}$ slides along the surface towards the first at $3 \mathrm{~m} / \mathrm{s}$. If the masses make a perfectly inelastic collision, then find amplitude and time period of oscillation of combined mass.