Question

Nucleus of mass number A, originally at rest, emits an $\alpha$ -particle with speed v. The daughter nucleus recoils with a speed

• A. $\frac{2v}{(A+4)}$
  
• B. $\frac{4v}{(A+4)}$
  
• C. $\frac{4v}{(A-4)}$
  
• D. $\frac{2v}{(A-4)}$

Answer 1

The correct option is C $\frac{4v}{(A-4)}$




According to conservation of momentum $4v=(A-4)v^{\prime }\Rightarrow v^{\prime }=\frac{4v}{A-4}$.