question_answer

A radioactive nucleus undergoes a-emission to form a stable element. What will be the recoil velocity of the daughter nucleus if V is the velocity of a-emission and A is the atomic mass of radioactive nucleus                               [DCE 2000; AIIMS 2004]

A)            \[\frac{4V}{A-4}\]              

B)            \[\frac{2V}{A-4}\]

C)            \[\frac{4V}{A+4}\]             

D)            \[\frac{2V}{A+4}\]

Correct Answer: A

Solution :

           According to conservation of momentum \[4v=(A-4)v'\]  Þ   \[v'=\frac{4v}{A-4}\].