If $x , v$ and a denote the displacement, the velocity and the acceleration of a particle executing simple harmonic motion of time period T, then, which of the following does not change with time?\\
(1) $a ^ { 2 } T ^ { 2 } + 4 \pi ^ { 2 } v ^ { 2 }$\\
(2) $\frac { a T } { x }$\\
(3) $a T + 2 \pi v$\\
(4) $\frac { a T } { v }$