A groups of physics students set up one configuration for a collisions between two dynamics carts, and they
conducted many trials. For each trial, they used the pre-collision and post-collision velocity measurements, along with the mass of each cart, to calculate the change in total momentum and the change in total energy. Since all the trial conditions were identical, they were justified in tabulating the average change in momentum and the average change in energy. They also calculated standard uncertainty (Δ x) values.
Other groups set up different configurations for collisions, but ran multiple trials and calculated their own average changes in momentum and changes in energy. These values, for all the groups, are summarized in the table below (x ¯ ± Δ x).