Q. The radioactive nucleus of mass number $A,$ initially at rest, emits an $\alpha -$ particle with a speed$v$. The recoil speed of the daughter nucleus will be
A) $\frac{2v}{A - 4}$
B) $\frac{2v}{A + 4}$
C) $\frac{4v}{A - 4}$
D) $\frac{4v}{A + 4}$
Explanation
(c) From conservation of momentum
$4v\ = (A - 4)v_{1}$
$\ \ \ \ \ \ \ \ v_{1} = \left( \frac{4v}{A - 4} \right)$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.