A mass with m$=650\mathrm{.}0$ g is hung vertically from a strange spring which has force F $=-$ax$3,$ where a$=25\mathrm{.}0$ N$/$m$3$ and x$=0$ corresponds to the equilibrium position of the spring with no mass on it $($here x is in the vertical direction$).$ a$)[3$ points$]$ What is the new equilibrium position for the mass when it is hung from the spring? b$)[7$ pts$]$ What is the frequency for small oscillations when this mass is hung from this spring?