Two students are on a balcony 18.5 m above the street. one student throws a ball ver- tically downward at 13.8 m/s; at the same instant, the other student throws a ball verti- cally upward at the same speed. the second ball just misses the balcony on the way down. how far apart are the balls 0.361 s after they are thrown? the acceleration of gravity is 9.8 m/s2 .