marble rolled out of its crater, as shown in Figure \[fig:crater\_rollout\]. An impact was classified as a [*stop*]{} if the marble rested inside its impact crater after impact, as shown in Figure \[fig:crater\_stop\].

Using different initial pendulum heights and stop-bar positions, setting the impact angle, we classified the outcomes of 120 impacts as ricochet, stop or roll-outs. For each impact, we recorded the initial pendulum drop height $h$ and the angle of the stop-bar $\theta_{sb}$. These two measurements were used to estimate the velocity of impact $v_{impact}$ and the angle of impact $\theta_{impact}$, measured from horizontal so that a grazing impact has a low impact angle. The classifications are plotted with different point types and colors in Figure \[fig:ric\] and as a function of computed $v_{impact}$ and $\theta_{impact}$.

We describe how impact velocity and impact angle are computed from the initial pendulum drop height $h$ and stop-bar angle $\theta_{sb}$. The initial drop height from the mechanism base, $h$, and distance of pendulum top to mechanism base when vertical, $d_base$, as shown in Figure \[fig:pend\], are used to calculate the initial angle of the pendulum $\alpha$, (measured from vertical) with $\cos \alpha = 1 - \frac{h-d_{base}}{L}$ and using the pendulum length 