(II) Obtain the displacement $x$ as a function of time for the simple harmonic oscillator using the conservation of energy, Eqs. $10 .[$Hint. Integrate Eq. 11 a with $v=d x / d t .]$
$\begin{array}{rlr}{E} & {=\frac{1}{2} m(0)^{2}+\frac{1}{2} k A^{2}=\frac{1}{2} k A^{2}} \\ {E} & {=\frac{1}{2} m v^{2}+\frac{1}{2} k(0)^{2}=\frac{1}{2} m v_{\max }^{2}} \\ {E} & {=\frac{1}{2} m v^{2}+\frac{1}{2} k x^{2}}\end{array}$