1. The problem statement, all variables and given/known data Two objects moving in opposite directions with the same speed undergo a totally inelastic collision, and half the initial kinetic energy is lost. Find the ratio of their masses, m1/m2. 2. Relevant equations m1v1+m2v2=(m1+m2)vf The objects are moving in opposite directions with the same speed, so v1=-v2=v 3. The attempt at a solution The part that gets me is the part that says half the kinetic energy is lost. Could someone explain how I factor that into the equations? If I just solve for m1/m2, plugging in 1/2v for vf(I don't know if that's right) I get 3, which is not the correct answer.