Q.

A nucleus with mass number 184 initially at rest emits an α-particle. If the Q value of the reaction is 5.5 MeV, calculate the kinetic energy of the α-particle

1 5 MeV  
2 5.5 MeV  
3 0.12 MeV  
4 5.38 MeV  

Ans.

(4)

12(4m)v2+12(180m)(4v180)2=5.5 MeV

12(4mv2)[1+45(4180)2]=5.5 MeV

⇒K.E.α=5.51+45(4180)2MeV    

K.E.α=5.38 MeV