Jeanette is playing in a 9-ball pool tournament. She will win ifshe sinks the 9-ball from the final rack, so she needs to line upher shot precisely. Both the cue ball and the 9-ball have massImage for Jeanette is playing in a 9 - ball pool tournament. She will win ifshe sinks the 9 - ball from the final rack, and the cue ball is hit at an initial speed of v_i. Jeanette carefully hits the cue ball into the9-ball off center, so that when the balls collide, they move awayfrom each other at the same angle theta from the direction in which the cue ball was originallytraveling (see figure). Furthermore, after the collision, the cueball moves away at speed v_f, while the 9-ball moves at speed v_9. View Figure
For the purposes of this problem, assume that the collision isperfectly elastic, neglect friction, and ignore the spinning of theballs. Find the angle theta that the 9-ball travels away from the horizontal.