For series combination of the spring, equivalent spring constant is given by, keq1=k11+k21.
Therefore, for combined system net spring constant keq=2k+k2k×k+k=35k
Angular frequency of oscillation (ω)=mkeq
⇒(ω)=3m5k
Period of oscillation (τ)=ω2π=2π5k3m
=π5k12m
Therefore, α=12.