In the mechanical system shown in Figure 8.16, all parameter values are in consistent physical units. Assume that the applied forces \(f_{1}\) and \(f_{2}\) are unit-step functions and that the system is subject to zero initial conditions. Plot two response curves for \(x_{1}\) : one for the case when \(f_{1}\) is the only input, and another for the case when \(f_{2}\) is the only input. Find the superposition of the two plots to determine the total response \(x_{1}\).

FIGURE 8.16 Mechanical system in Example 8.9. k = 2 0000 f = u(t) k-1 mo 2= u(t) b =0.8 m = 2 m = 1 x2