posted by Lily .
a 10.0-g object moving to the right at 20.0 cm/s makes a elastic head-on collision with a 15-g object moving in the opposite direction at 30.0 cm/s find the velocity of each object after the collision.
YOu have two equation, momentum, and energy. Use the momentum to find the velocity of one in terms of the other. Then substitute that found velocity in to the energy equation, and grind it out.
I have for about an hour and a half and I am still not getting the right answer.