physics
posted by Randy .
Object A, which has mass m and a velocity Voi,collides with the Object B,which has mass 2m and a velocity 1/2Voj.Following the collision ,object B has a velocity of 1/4Voi.(a) Determine the velocity of object A after the collision.(b) Is the collision elastic? If not, express the change in the kinetic energy in terms of m and Vo.

Have you tried to start with the conservation of momentum?
mVoi+mVoj=2mVoi/4+m*x
x=(Voi+VojVoi/2)=Voi/2+Voj
Now, check the KE before the reaction, and the KE after the collision, and see if they are equal.