Angular position φ(τ) normalized to its amplitude 2χ₀ as a function of t for various values of the parameters v and l_p. We have taken g = 274 m s^-2 and typical values of ζ = 100 and r = 60 Mm. In all cases the period is 49 min. The black curve corresponds to v = 30 km s^-1 and l_p = 2 Mm, the green curve to v = 10 km s^-1 and l_p = 2 Mm, the red curve to v = 40 km s^-1 and l_p = 5 Mm, and the blue curve to v = 10 km s^-1 and l_p = 5 Mm. The damping times for these combinations of parameters are t_d = 55.6, 166.7, 138.9, and 416.7 min, respectively.