A second order system has a transfer function given by
$$ G(s)=\frac{25}{s^2+8 s+25} $$
If the system, initially at rest is subjected to a unit step input at $\mathrm{t}=0$, the second peak in response will occur at
- $\pi \mathrm{sec}$
- $\frac{\pi}{3}$ sec
- $\frac{2 \pi}{3} \sec$
- $\frac{\pi}{2}$ sec