An object of mass \(2.0 \text{ kg}\) moves along the \(x\)-axis with an initial velocity of \(-3.0 \text{ m/s}\) at time \(t = 0\). The object is acted upon by a net force \(F_x(t)\) directed along the \(x\)-axis, as shown in the graph. The force is described by the quadratic function \(F_x(t) = 12t - 3t^2\) for \(0 \le t \le 4.0 \text{ s}\), and decreases linearly from \(0 \text{ N}\) at \(t = 4.0 \text{ s}\) to \(-12 \text{ N}\) at \(t = 6.0 \text{ s}\). What is the magnitude of the linear momentum of the object at \(t = 6.0 \text{ s}\)?