  The presence of ambient air in liquid-slamming events plays a crucial role in
influencing the shape of the liquid surface prior to the impact, and the
distribution of loads created upon impact. We study the role of trapped air in
a simplified geometry by slamming a flat disc on a stationary water bath. We
show how air trapping influences pressure peaks at different radial locations
on the disc, how the pressure impulses are affected, and whether local pressure
impulses differ from area-integrated (force) impulses due to impact. We
emphasize that pressure impulses are a much more faithful indicator of the
intensity of an impact event, being less affected by transients in the signals,
and obeying the relevant inertial length and time scales.
