Two masses  ${\mathrm{m}}_1$ and ${\mathrm{m}}_2$ are suspended together by a massless spring of spring constant  $k$ (Fig.). When the masses are in equilibrium, ${\mathrm{m}}_{\mathrm{1 }}$is removed without disturbing the system. Find the angular frequency of  osillation of ${\mathrm{m}}_2$