for f in np.arange(1.4,1.6,0.05):
    TF = sp.lti([1],[1,0,2.25])
    t = np.linspace(0,200,1001)
    fx = np.cos(f*t)*np.exp(-0.05*t)
    t,x,_ = sp.lsim(TF,fx,t)
    plt.plot(t,x)
    plt.title("Forced Damping Oscillator with frequency: "+str(f))
    plt.xlabel("Time")
    plt.ylabel("x")
    plt.show()