Q$30.$

A $3\mathrm{.}0$ kg object is in simple harmonic motion in one dimension and moves according to the equation

$x(t)=(5\mathrm{.}0m)cos[(\frac{}{3}ra\frac{d}{s})t-\frac{}{4}$rad$],$

where $t$ is in seconds. How much time is needed for the object to move from its equilibrium position