Q.

Two particles of masses m1,m2 move with initial velocities u1 and u2. On collision, one of the particles gets excited to a higher level, after absorbing energy ε. If final velocities of particles be v1 and v2, then we must have                [2015]
 

1 12m1u12+12m2u22-ε=12m1v12+12m2v22  
2 12m12u12+12m22u22+ε=12m12v12+12m22v22  
3 m12u1+m22u2-ε=m12v1+m22v2  
4 12m1u12+12m2u22=12m1v12+12m2v22-ε  

Ans.

(1)

Total initial energy of two particles

      =12m1u12+12m2u22

Total final energy of two particles

       =12m2v22+12m1v12+ε

Using energy conservation principle,

        12m1u12+12m2u22=12m1v12+12m2v22+ε

    12m1u12+12m2u22-ε=12m1v12+12m2v22