In a lab experiment, a student is trying to apply the conservation of momentum. two identical balls, each with a mass of 1.0 kg, roll toward each other and collide. the velocity is measured before and after each collision. the collected data is shown below. a 5 column table with 3 rows. the first column is unlabeled with entries trial 1, trial 2, trial 3, trial 4. the second column is labeled initial velocity ball a (meters per second) with entries positive 1, positive 0.5, positive 2, positive 0.5. the third column is labeled initial velocity ball b (meters per second) with entries negative 2, negative 1.5, positive 1, negative 1. the third column is labeled final velocity ball a (meters per second) with entries negative 2, negative 0.5, positive 1, positive 1.5. the fourth column is labeled final velocity ball b (meters per second) with entries negative 1, negative 0.5, negative 2, negative 1.5. which trial shows the conservation of momentum in a closed system? trial 1 trial 2 trial 3 trial 4