One ball of mass 575 g traveling $3.50 \mathrm{m} / \mathrm{s}$ to the right collides with another ball of mass $425 \mathrm{g}$ that is initially at rest. After the collision, the lighter ball is traveling $4.03 \mathrm{m} / \mathrm{s} .$ What is the velocity of the heavier ball after the collision?