Answer
$v=-49\frac{m}{s}$
Work Step by Step
The given position function is,
$x=6 cos(3{\pi}t+\frac{\pi}{3})$
Differentiating both sides with respect to $t$, we obtain:
$v=-6\times 3\pi sin(3{\pi}t+\frac{\pi}{3})$
At $t=2.0 s$ and plugging in the other known values we obtain:
$v=-6\times(3\times3.1416)sin(3\times3.1416(2)+\frac{3.1416}{3})$
$v=-49\frac{m}{s}$
