The 15 g head of a bobble-head doll oscillates in $\mathrm{SHM}$ at a frequency of $4.0 \mathrm{Hz}$
a. What is the spring constant of the spring on which the head is mounted?
b. Suppose the head is pushed $2.0 \mathrm{cm}$ against the spring, then released. What is the head's maximum speed as it oscillates?
c. The amplitude of the head's oscillations decreases to $0.5 \mathrm{cm}$ in $4.0 \mathrm{s}$. What is the head's damping constant?