Seven pool balls are situated at rest as shown in Fig. 5.45 . The middle ball su

Question

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?

Explanation / Answer

first thing to note is that the collisions are not one dimentional(head on collisions) and other thing is all the balls around center ball are symetrically placed. so when center ball collides with all other balls one by one, each ball gets some velocity in space. by symmetry we can say net velocity gained by all balls is zero whether in x axis or y axis. thus net velocity given by center ball after collision with all six balls is zero.

hence there is no change of velocity of center ball after collision with all six balls. so its velocity remains to be v towards right

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.