Forced response of a collisional ring to first-order Lindblad resonances: 2/1 inner resonance (m = 2, j = 1) in the upper row and 2/3 outer resonance (m = −2, j = 1) in the lower row. In both cases the ringlet is centered at unit distance, and is composed of 7 500 particles with radius 0.0005; the satellite has a mass µ_s = 2 × 10⁻⁴ relative to the spherical central body. In the frames 50 snapshots have been stacked in a coordinate system corotating with the satellite (the satellite location is shown by the white square). In the left frame, the particle deviations from the ringlet mean distance have been exaggerated by a factor of 10. In the right frames the ringlet width has been exaggerated by a factor of 20. In the right frames the blue (red) contours indicate regions where T_rt is negative (positive). The line indicates the direction where the ring width is the smallest. Local shear reversal, corresponding to negative T_rt, is seen in the ring regions where particles are approaching the width minimum.