Question

Three identical balls $P_1,P_2$ and $P_3$ are placed on a frictionless surface in a straight line. The mass of each is $m$. Another ball $P$ moving with velocity $v$ collides directly with the three balls as shown in figure. The collision is perfectly elastic; now determine the velocity of all the four balls.

Answer 1

For same mass collision as elastic then velocity will $\overrightarrow{v}$ interchanged. Therefore, then this case follows :

Ref. image

(a) initial position

Ref. image

(b) after first collision assume separation isversy low

Ref. image

(c) second collision of $P_1$ and $P_2$ At last $p,P_1$ and $P_2$ get rest and

Ref. image

(d) last collision with $P_2$ and $P_3$

$P_3$ move with $\overrightarrow{v}$ velocity.

Hence, solved.