A 2.0-kg ball rolls to the right at 3.0 m/s. A 4.0-kg ball rolls to the left at 2.0 m/s. What is the momentum of the system after a head-on collision of the two balls?

Final momentum after a head on collision is - 2kgm/s

Explanation:

One ball moves to the right and the other moves opposite and momentum is a vector quantity so that considering the direction

Initial momenta are P₁=2x3=6kgm/s P₂=4x (-2) = -8kgm/s

Final momentum is the vector sum of P (final) = 6-8 = - 2 kgm/s