How angular velocity changes with the initial tilt angle θ₀ of the secondary. Top panel: ω₀ is affected when there is contact between the surfaces (blue) and when the surface-to-surface distance increases (red) as the secondary is tilted (see also Fig. 2). The mass ratio is q = 0.1 for the data in the top panel. Bottom panel: relative difference in ω₀ between the two approaches shown in Fig. 2, but for three different mass ratios q. The mass ratio is defined as q = m_s/m_v.