[单选题]
A red ball with a velocit gix m3.6tn6cwy of2,3g5j4e mvs v6uqt yd*vfp6j +3.0 m/s collides head-on with a yellow ball of equal mass moving with a velocity of -2.0 m/s. What is the velocity of the yellow ball after the collision u 456vqs gdf,jtvmyj362vp e*?
