(P.9) Two objects colliding

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

B) Their velocities will be reduce

C) Their velocities will be unchanged

D) Their velocities will be zero

E) Their velocities may be zero



I know the answer is E but why? What I understand is that when 2 cars collapse head on, they go backwards