Question

Two masses $m_{a}$ and $m_{b}$ moving with velocities $v_{a}$ and $v_{b}$ in opposite direction collide elastically and after the collision $m_{a}$ and $m_{b}$ move with velocities $v_{b}$ and $v_{a}$ respectively. Then the ratio $\frac{m_{a}}{m_{b}}$ is

• A. $\frac{v_{a}-v_{b}}{v_{a}+v_{b}}$
• B. $\frac{v_{a}+v_{b}}{v_{a}-v_{b}}$
• C. 1
• D. $\frac{1}{2}$

Answer 1

Answer: (C)

As velocities are exchanged on perfectly elastic collision, therefore, masses of two objects must be equal.
$\therefore \frac{m_{a}}{m_{b}}=1$ or $m_{a}=m_{b}$