physics
posted by Alex .
A 550g ball traveling at 8.0 m/s undergoes a headon elastic collision with a 250g ball traveling toward it also at 8.0 m/s. What is the speed of the 250g mass after the collision?

You just have to use both momentum and energy equations, and do the messy algebra. Two equations, two unknowns (the two ball velocities after collision).
Enjoy the messy algebra.