Positions, velocities, and accelerations for representative cork A in fibril 1 as functions of time. In each panel the cork formation period, defined by the upswing of the photospheric box oscillation, is shaded a lighter grey and the fibril destruction period is shown in a darker grey. Top row, left: cork position (solid), box oscillation for comparison (dashed, on an arbitrary scale); centre: vertical components of magnetic pressure and tension, along with their sum, the Lorentz force; right: additional panel only in this figure, showing vertical force components averaged over cork A and the two corks that were closest to it at the seed time. Second row: cork velocity with a v_z = 0 line over-plotted for reference. Third row: cork acceleration computed for three different assumptions. Red: computed from all forces acting on the cork; blue: computed only from the Lorentz force, gas pressure gradient, and gravity; green: computed as the time derivative of the velocity in panel b. Fourth row: acceleration owing to the gas pressure gradient, the Lorentz force, and gravity, as well as their sum (a_PLG). Left column: vertical direction. Middle column: direction tangential to the field line (the T-direction in the Frenet-Serret frame). Right column: direction normal to the field line (the N-direction).