Seven pool balls are situated at rest as shown in Fig. 5.45 . The middle ball suddenly somehow acquires a speed v to the right. Assume that starting with ball A , the balls spiral out an infinitesimal amount. So A is closer to the center ball than B is, and B is closer than C is, etc. This means that the center ball collides with A first, then it gets deflected into B , and then it gets deflected into C , and so on. But all the collisions happen in the blink of an eye. What will the center ball’s velocity be after it collides (elastically)
 with all six balls?

Fig. 5.44 F E A D B