Q. A smooth sphere of mass $M$ moving with velocity $u$ directly collides elastically with another sphere of mass $m$ at rest. After collision their final velocities are $V$ and $v$ respectively. The value of $v$ is
A) $\frac{2uM}{m}$
B) $\frac{2um}{M}$
C) $\frac{2u}{1 + \frac{m}{M}}$
D) $\frac{2u}{1 + \frac{M}{m}}$
Explanation
(c) $v_{2} = \left( \frac{m_{2} - m_{1}}{m_{1} + m_{2}} \right)u_{2} + \frac{2m_{1}u_{1}}{m_{1} + m_{2}} = \frac{2mu}{M + m} = \frac{2u}{1 + \frac{m}{M}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.