Question

A nucleus of mass number A originally at rest emits a alpha particle with speed V.The recoil speed of daughter's nucleus is

Answer 1

Applying principle of conservation of momentum (taking mass of alpha particle =4 units).
Let speed of alpha particle = V m/s

4 V + 206 V' = 0where, V' is velocity of residual nucleus.4 V = - 206 V'V' = - 4 V206K.E. of residual nucleus = 1/2 mv2 = 12 × 206 ×- 4 V2062 = 4103 V2