$\left\{ \begin{matrix} E=\frac{1}{2}m{{A}^{2}}{{\omega }^{2}}=\frac{1}{2}K{{A}^{2}}=\frac{1}{2}\times 200\times {{(5\times {{10}^{-2}})}^{2}}=0/25J  \\ K=m{{\omega }^{2}}  \\ \end{matrix} \right.$