1. The problem statement, all variables and given/known data Two objects of equal mass traveling toward each other with equal speeds undergo a head on collision. Which one of the following statements concerning their velocities after the collision is necessarily true? (a) They will exchange velocities. (d) Their velocities will be zero. (b) Their velocities will be reduced. (e) Their velocities may be zero. (c) Their velocities will be unchanged. 2. Relevant equations I know there is elastic and inelastic coallison elastic keeps KE inelastic loses KE 3. The attempt at a solution I would say that since both cars have SAME MASS AND SAME VELOCITIES they they will cancel each other right? and therefore their velocities will be zero so answer is D but right answer is E, my question is why do they say "may be" zero?????