A \(4.0\text{ kg}\) object moves along the \(x\)-axis on a frictionless horizontal surface. The net force \(F_x\) acting on the object as a function of position \(x\) is shown in the graph. At \(x = 0\text{ m}\), the object is moving in the positive \(x\)-direction with a speed of \(4.0\text{ m/s}\). What is the speed of the object when it reaches \(x = 8.0\text{ m}\)?