Question

A body of mass $m \, kg$ collides elastically with another body at rest and then continues to move in the original direction with one half of its original speed. The mass of the target body is

• A. $m \, kg$
• B. $\frac{2}{3}m \, kg$
• C. $\frac{m}{3} \, kg$
• D. $\frac{m}{2} \, kg$

Answer 1

Answer: (C)

Velocity of the colliding body after elastic collision is,
$v_{1}=u_{1}+\frac{2 m_{2}}{m_{1} + m_{2}}\left(u_{2} - u_{1}\right)$
$\frac{u_{1}}{2}=u_{1}+\frac{2 m_{2}}{m + m_{2}}\left(0 - u_{1}\right)$
$\frac{m_{2}}{m + m_{2}}=\frac{1}{4}$
$m_{2}=\frac{m}{3} \, kg$