Question

Three particles $A,B$ and $C$ of equal masses move with equal speeds $v$ along the medians of an equilateral triangle. They collide at the centroid $O$ of the triangle. After collision $A$ comes to rest while $B$ retraces its path with speed $v$ The velocity of $C$ is then

• A. $v$, direction $\overrightarrow{OA}$
• B. $2v$, direction $\overrightarrow{OA}$
• C. $2v$, direction $\overrightarrow{OB}$
• D. $v$, direction $\overrightarrow{BO}$

Answer 1

Answer: (D)

Initial momentum of system is zero. So, final momentum should also be zero. Finally A comes to rest after collision, so to have final momentum zero, B and C should move in opposite directions