Question

A 7.28-kilogram bowling ball traveling 8.50 meters per second east collides head-on with a 5.45 kilogram bowling ball traveling 10.0 meters per second west. Determine the magnitude of the total momentum of the two-ball system after the collision

Answer 1

Considering Conservation of Momentum, the momentum $p=mv$ before and after must remain the same:
so:
before: $7.28*8.50-5.45*10.0=7.38 kg \frac{m}{s}$