Question

Two identical balls $A$ and $B$ having velocities of $0.5\, m / s$ and $-0.3\, m / s$ respectively collide elastically in one dimension. The velocities of $B$ and $A$ after the collision respectively will be -

• A. $-0.5 \,m / s$ and $0.3\, m / s$
• B. $0.5\, m / s$ and $-0.3\, m / s$
• C. $-0.3\, m / s$ and $0.5\, m / s$
• D. $0.3\, m / s$ and $0.5\, m / s$

Answer 1

Answer: (B)

$0.5\, m / s$ and $-0.3\, m / s$

Answer 2

On elastic collision between two masses moving with finite velocities, their velocities get exchanged and they travel in opposite directions as they were initially.
Hence the velocity of $B$ is $+0.5 m / s$ and that of $A$ is $-0.3 m / s$