Q. A body of mass $2kg$ makes an elastic collision with another body at rest and continues to move in the original direction with one fourth of its original speed. The mass of the second body which collides with the first body is
A) $2\ kg$
B) $1.2\ kg$
C) $3\ kg$
D) $1.5\ kg$
Explanation
(b) $m_{1} = 2\ kg$ and $v_{1} = \left( \frac{{m_{1} - m}_{2}}{m_{1} + m_{2}} \right)u_{1} = \frac{u_{1}}{4}$ [Given]
By solving we get $m_{2} = 1.2\ kg$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.