1) A 10.0-g object moving to the right at 20 cm/s makes an elastic head-on collision with a 15.0-g object moving in the opposite direction at 30.0 cm/s. Find the velocity of each object after collision. 2) A billiard ball rolling across a table at 1.50 m/s makes a head on elastic collision with an identical ball. Find the speed of each ball after the collision (a) when the second ball is initially at rest (b) when the second ball is moving toward the first at a speed of 1.00 m/s and (c) when the second ball is moving away from the first at a speed of 1.00 m/s. I have no idea where to start... Thanks for the help, I really appreciate it.