Class 11 NEET Physics Work, Energy and Power Questions

Mass of body (m1)=m; Velocity of first body (u1)=3km/ hour; Mass of second body at rest (m2)=2m and velocity of second body(u2)=0.
After combination, mass of the body
M=m+2m=3m
From the law of conservation of momentum, weget
Mv=m1u1+m2u2
or 3mv=(m×3)+(2m×0)=3m
or v=1 km/ hour.