was the largest discrepancy between the estimated and measured impact angles. Estimated and measured impact velocities agree. The discrepancy in impact angle is discussed below.

Figure \[fig:ric\] shows that the dividing line between different outcomes is quite sensitive to the angle of impact. The dividing line trend is opposite to that found by @soliman76 as we see the critical grazing impact angle dividing ricochets from roll-outs increases as a function of impact velocity, rather than decreases. There are some differences between our experiments and theirs that might explain this difference in behavior. Our projectile density is similar to the substrate density (glass marbles into sand), whereas @soliman76 used denser projectiles (steel, aluminum and lead balls into sand). Their projectiles have higher velocity (theirs were up to 180 m/s and ours are below 5 m/s). Both our and their projectiles are spherical. It is useful to define a dimensionless number known as the Froude number $$Fr \equiv \frac{v}{\sqrt{gR_p}}$$ with $R_p$ the projectile radius. Both sets of experiments can be considered at high Froude number where impact velocity gives $Fr  > 1$. The Froude number of our impacts are 10–20, whereas those by @soliman76 are 300–600. Our projectiles remain in a shallow 