A particle executes simple harmonic motion with an amplitude of $5 cm$. When the particle is at $4 cm$ from the mean position, the magnitude of its velocity in SI units is equal to that of its acceleration. Then, its periodic time in seconds is:\\
(1) $\frac { 8 \pi } { 3 }$\\
(2) $\frac { 3 } { 8 } \pi$\\
(3) $\frac { 4 \pi } { 3 }$\\
(4) $\frac { 7 } { 3 } \pi$