Answer:
0 kg m/s before and after collision
Explanation:
Let m, v be the mass and speed of the 2 balls, respectively, before the collision. Since they have the same mass and same speed but in opposite direction, the total momentum of the system would be:
P = mv - mv = 0 kg m/s
As the collision is elastic. The total momentum after the collision is the same as the total momentum before the collision, which is 0.
