PHYSICS
posted by mark .
2 pool balls of equal mass experience a perfectly elastic head on collision. 1 ball is traveling at 2m/s and the other at 3m/s in the opposite direction.What is thier speed just after impact? I know the balls swap speed and change direction but can't find the correct formula to prove this. Please help!

There is a good derivation here. Be sure to set m1 = m2 to prove that thay switch velocities and directions.
http://blog.weber.k12.ut.us/jrhoades/files/2010/11/Ch7APNotesElasticCollisionFormula.pdf