A small block of mass 20.0 grams is moving to the right on a horizontal frictionless surface with a speed of 0.68 m/s. The block has a head-on elastic collision with a 40.0 gram block that is initially at rest. Since the collision is head-on, all velocities lie along the same line, both before and after the collision.
(a) What is the speed of the 20.0 gram block after the collision?
(b) What is the speed of the 40.0 gram block after the collision?