1. The problem statement, all variables and given/known data Two wooden blocks of mass 8 kg and 4 kg respectively approach each other from opposite directions on a smooth level surface at a relative speed of 16 m s^1 . After a head-on collision they separate at a relative speed of 6 m s^1 . The initial velocity of the 8 kg block was 7 m s -1 North. Find the velocity of (a) the 4 kg block immediately before the impact; (b) the 8 kg block immediately after the impact; (c) the 4 kg block immediately after the impact. 2. Relevant equations f=ma F x delta T= delta P For an elastic collision va-vb = -(va'-vb') 3. The attempt at a solution Part (a) is straightforward Part (b) appears awkward because the collision seems inelastic because the relative velocity after impact is different in magnitude to that before impact and doesn't follow the relationship: va-vb = -(va'-vb') Am I correct in assuming the collision to be inelastic? How does one approach a solution to problem (b)? Help and guidance gratefully received.