To evaluate impact resistance, a test engineer drops a prototype smartphone casing vertically from rest. A high-speed sensor located just above the impact zone measures the time taken for a small indicator strip of known width on the casing to pass through its line of sight, which is used to calculate the speed of the casing just before impact.
State two additional physical measurements the engineer must record in order to calculate the decrease in gravitational potential energy and the increase in kinetic energy of the casing during the fall.