Top panels: Evolution of the net vertical force (positive values are plotted in red, and negative values are shown in blue) at z = 24 Mm for a) t = 4.5 min, b) t = 4.96 min, c) t = 6.11 min, d) t = 7.63 min, and e) t = 8.78 min. The magenta lines correspond to field lines computed within the flux rope. The grey contours indicate positive (solid) and negative (dashed) values of B_z at z = 0.05 Mm, and the green contours exhibit different values of v_z between 218 (dark green) and 436 km s⁻¹ (light green). Bottom panels: Flux rope magnetic field lines in 3D coloured by v_z for the same times as in the top panels. The semi-transparent grey plane corresponds to z = 24 Mm and contains the same v_z contours as the top panels.