Billiard ball $A$ is moving in the $y$ -direction with a velocity of $2 \mathrm{m} / \mathrm{s}$ when it strikes ball $B$ of identical size and mass initially at rest. Following the impact, the balls are observed to move in the directions shown. Calculate the velocities $v_{A}$ and $v_{B}$ which the balls have immediately after the impact. Treat the balls as particles and neglect any friction forces acting on the balls compared with the force of impact.