Use a numerical method to compute and plot the free response of equation (13.6.10) for m = 1, c = 0, k1 = 2, and k3 = 0.1, for (0) = 0 and two initial conditions: y(0) = 10 and y(0) = 40. Compare the results with those shown in Figure 13.6.4. How does the initial condition affect the frequency of the response?